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Esotropia and Exotropia Preferred Practice Pattern®

Published:November 03, 2017DOI:https://doi.org/10.1016/j.ophtha.2017.10.007
      AMERICAN ACADEMY™ OF OPHTHALMOLOGY
      Protecting Sight. Empowering Lives.™
      Esotropia and Exotropia Preferred Practice Pattern®
      © 2017 Published by Elsevier Inc. on behalf of the American Academy of Ophthalmology
      ISSN 0161–6420/17
      Secretary for Quality of Care
      Timothy W. Olsen, MD
      Academy Staff
      Jennifer Harris, MS
      Doris Mizuiri
      Andre Ambrus, MLIS
      Flora C. Lum, MD
      Medical Editor: Susan Garratt
      Approved by: Board of Trustees
      September 9, 2017
      © 2017 American Academy of Ophthalmology®
      All rights reserved
      AMERICAN ACADEMY OF OPHTHALMOLOGY and PREFERRED PRACTICE PATTERN are registered trademarks of the American Academy of Ophthalmology. All other trademarks are the property of their respective owners.
      Preferred Practice Pattern® guidelines are developed by the Academy's H. Dunbar Hoskins Jr., MD Center for Quality Eye Care without any external financial support. Authors and reviewers of the guidelines are volunteers and do not receive any financial compensation for their contributions to the documents. The guidelines are externally reviewed by experts and stakeholders before publication.
      Correspondence:
      Flora C. Lum, MD, American Academy of Ophthalmology, P. O. Box 7424, San Francisco, CA 94120–7424.

      PEDIATRIC OPHTHALMOLOGY/STRABISMUS PREFERRED PRACTICE PATTERN® DEVELOPMENT PROCESS AND PARTICIPANTS

      The Pediatric Ophthalmology/Strabismus Preferred Practice Pattern® Panel members wrote the Esotropia and Exotropia Preferred Practice Pattern® guidelines (PPP). The PPP Panel members discussed and reviewed successive drafts of the document, meeting in person twice and conducting other review by e-mail discussion, to develop a consensus over the final version of the document.
      Pediatric Ophthalmology/Strabismus Preferred Practice Pattern Panel 2016–2017
      Stephen P. Christiansen, MD
      Derek T. Sprunger, MD
      Michele Melia, ScM, Methodologist
      Katherine A. Lee, MD, PhD, American Academy of Pediatrics Representative
      Christie L. Morse, MD, American Association for Pediatric Ophthalmology & Strabismus Representative
      Michael X. Repka, MD, MBA
      David K. Wallace, MD, MPH, Chair
      The Preferred Practice Patterns Committee members reviewed and discussed the document during a meeting in April 2017. The document was edited in response to the discussion and comments.
      Preferred Practice Patterns Committee 2017
      Robert S. Feder, MD, Chair
      Roy S. Chuck, MD, PhD
      Steven P. Dunn, MD
      Francis S. Mah, MD
      Randall J. Olson, MD
      Bruce E. Prum, Jr., MD
      David K. Wallace, MD, MPH
      David C. Musch, PhD, MPH, Methodologist
      The Esotropia and Exotropia PPP was then sent for review to additional internal and external groups and individuals in July 2017. All those returning comments were required to provide disclosure of relevant relationships with industry to have their comments considered (indicated with an asterisk below). Members of the Pediatric Ophthalmology/Strabismus Preferred Practice Pattern Panel reviewed and discussed these comments and determined revisions to the document.
      Academy Reviewers
      Board of Trustees and Committee of Secretaries*
      Council*
      General Counsel*
      Basic and Clinical Science Course Section 6 Subcommittee*
      Ophthalmic Technology Assessment Committee Pediatric Ophthalmology/Strabismus Panel*
      Practicing Ophthalmologists Advisory Committee for Education
      Invited Reviewers
      American Academy of Family Physicians*
      American Assocation of Certified Orthoptists*
      American Association for Pediatric Ophthalmology & Strabismus
      American Academy of Pediatrics, Section on Ophthalmology
      American College of Preventive Medicine
      American College of Surgeons, Advisory Council for Ophthalmic Surgery
      American Foundation for the Blind
      Canadian Ophthalmological Society
      Consumer Reports Health Choices
      Foundation for Fighting Blindness
      Lighthouse Guild
      National Eye Institute
      National Federation of the Blind
      National Medical Association, Ophthalmology Section
      National Partnership of Women and Families
      Prevent Blindness*
      Oscar A. Cruz, MD
      Sean P. Donahue, MD, PhD*
      David A. Plager, MD

      FINANCIAL DISCLOSURES

      In compliance with the Council of Medical Specialty Societies' Code for Interactions with Companies (available at www.cmss.org/codeforinteractions.aspx), relevant relationships with industry are listed. The Academy has Relationship with Industry Procedures to comply with the Code (available at www.aao.org/about-preferred-practice-patterns). A majority (100%) of the members of the Pediatric Ophthalmology/Strabismus Preferred Practice Pattern Panel 2016–2017 had no financial relationship to disclose.
      Pediatric Ophthalmology/Strabismus Preferred Practice Pattern Panel 2016–2017
      Stephen P. Christiansen, MD: No financial relationships to disclose
      Katherine A. Lee, MD, PhD: No financial relationships to disclose
      Christie L. Morse, MD: No financial relationships to disclose
      Michael X. Repka, MD, MBA: No financial relationships to disclose
      Derek T. Sprunger, MD: No financial relationships to disclose
      Michele Melia, ScM: No financial relationships to disclose
      David K. Wallace, MD, MPH: No financial relationships to disclose
      Preferred Practice Patterns Committee 2017
      Roy S. Chuck, MD, PhD: No financial relationships to disclose
      Steven P. Dunn, MD: No financial relationships to disclose
      Robert S. Feder, MD: No financial relationships to disclose
      Francis S. Mah, MD: No financial relationships to disclose
      Randall J. Olson, MD: No financial relationships to disclose
      Bruce E. Prum, Jr., MD: No financial relationships to disclose
      David K. Wallace, MD, MPH: No financial relationships to disclose
      David C. Musch, PhD, MPH: No financial relationships to disclose
      Secretary for Quality of Care
      Timothy W. Olsen, MD: No financial relationships to disclose
      Academy Staff
      Andre Ambrus, MLIS: No financial relationships to disclose
      Susan Garratt, Medical Editor: No financial relationships to disclose
      Jennifer Harris, MS: No financial relationships to disclose
      Flora C. Lum, MD: No financial relationships to disclose
      Doris Mizuiri: No financial relationships to disclose
      The disclosures of relevant relationships to industry of other reviewers of the document from January to July 2017 are available online at www.aao.org/ppp.

      TABLE OF CONTENTS

      • OBJECTIVES OF PREFERRED PRACTICE PATTERN GUIDELINES P148
      • METHODS AND KEY TO RATINGS P149
      • HIGHLIGHTED FINDINGS & RECOMMENDATIONS FOR CARE P150
      • SECTION I. ESOTROPIA
      • INTRODUCTION P151
      • Disease Definition P151
        • Infantile Esotropia P151
        • Acquired Esotropia P151
        • Other P152
      • Patient Population P152
      • Clinical Objectives P152
      • BACKGROUND P152
      • Prevalence and Risk Factors P152
      • Natural History P153
      • Rationale for Treatment P153
      • CARE PROCESS P153
      • Patient Outcome Criteria P153
      • Diagnosis P154
        • History P154
        • Examination P154
      • Management P156
        • Prevention P156
        • Choice of Therapy P157
        • Perioperative Care P160
        • Follow-up Evaluation P161
      • Provider and Setting P161
      • Counseling and Referral P161
      • SECTION II. EXOTROPIA
      • INTRODUCTION P162
      • Disease Definition P162
        • Infantile Exotropia P162
        • Intermittent Exotropia P162
        • Convergence Insufficiency P162
        • Other P162
      • Patient Population P162
      • Clinical Objectives P163
      • BACKGROUND P163
      • Prevalence and Risk Factors P163
      • Natural History P163
      • Rationale for Treatment P163
      • CARE PROCESS P164
      • Patient Outcome Criteria P164
      • Diagnosis P164
        • History P164
        • Examination P164
      • Management P165
        • Choice of Therapy P165
        • Perioperative Care P165
        • Follow-up Evaluation P168
      • Provider and Setting P168
      • Counseling and Referral P168
      • SOCIOECONOMIC CONSIDERATIONS FOR STRABISMUS P168
      • APPENDIX 1. QUALITY OF OPHTHALMIC CARE CORE CRITERIA P170
      • APPENDIX 2. INTERNATIONAL STATISTICAL CLASSIFICATION OF DISEASES AND RELATED HEALTH PROBLEMS (ICD) CODES P172
      • LITERATURE SEARCHES FOR THIS PPP P174
      • RELATED ACADEMY MATERIALS P174
      • REFERENCES P174

       OBJECTIVES OF PREFERRED PRACTICE PATTERN® GUIDELINES

      As a service to its members and the public, the American Academy of Ophthalmology has developed a series of Preferred Practice Pattern® guidelines that identify characteristics and components of quality eye care. Appendix 1 describes the core criteria of quality eye care.
      The Preferred Practice Pattern® guidelines are based on the best available scientific data as interpreted by panels of knowledgeable health professionals. In some instances, such as when results of carefully conducted clinical trials are available, the data are particularly persuasive and provide clear guidance. In other instances, the panels have to rely on their collective judgment and evaluation of available evidence.
      These documents provide guidance for the pattern of practice, not for the care of a particular individual. While they should generally meet the needs of most patients, they cannot possibly best meet the needs of all patients. Adherence to these PPPs will not ensure a successful outcome in every situation. These practice patterns should not be deemed inclusive of all proper methods of care or exclusive of other methods of care reasonably directed at obtaining the best results. It may be necessary to approach different patients' needs in different ways. The physician must make the ultimate judgment about the propriety of the care of a particular patient in light of all of the circumstances presented by that patient. The American Academy of Ophthalmology is available to assist members in resolving ethical dilemmas that arise in the course of ophthalmic practice.
      Preferred Practice Pattern® guidelines are not medical standards to be adhered to in all individual situations. The Academy specifically disclaims any and all liability for injury or other damages of any kind, from negligence or otherwise, for any and all claims that may arise out of the use of any recommendations or other information contained herein.
      References to certain drugs, instruments, and other products are made for illustrative purposes only and are not intended to constitute an endorsement of such. Such material may include information on applications that are not considered community standard, that reflect indications not included in approved U.S. Food and Drug Administration (FDA) labeling, or that are approved for use only in restricted research settings. The FDA has stated that it is the responsibility of the physician to determine the FDA status of each drug or device he or she wishes to use, and to use them with appropriate patient consent in compliance with applicable law.
      Innovation in medicine is essential to ensure the future health of the American public, and the Academy encourages the development of new diagnostic and therapeutic methods that will improve eye care. It is essential to recognize that true medical excellence is achieved only when the patients' needs are the foremost consideration.
      All Preferred Practice Pattern® guidelines are reviewed by their parent panel annually or earlier if developments warrant and updated accordingly. To ensure that all PPPs are current, each is valid for 5 years from the approved by date unless superseded by a revision. Preferred Practice Pattern guidelines are funded by the Academy without commercial support. Authors and reviewers of PPPs are volunteers and do not receive any financial compensation for their contributions to the documents. The PPPs are externally reviewed by experts and stakeholders, including consumer representatives, before publication. The PPPs are developed in compliance with the Council of Medical Specialty Societies' Code for Interactions with Companies. The Academy has Relationship with Industry Procedures (available at www.aao.org/about-preferred-practice-patterns) to comply with the Code.
      Appendix 2 contains the International Statistical Classification of Diseases and Related Health Problems (ICD) codes for the disease entities that this PPP covers. The intended users of the Esotropia and Exotropia PPP are ophthalmologists.

       METHODS AND KEY TO RATINGS

      Preferred Practice Pattern® guidelines should be clinically relevant and specific enough to provide useful information to practitioners. Where evidence exists to support a recommendation for care, the recommendation should be given an explicit rating that shows the strength of evidence. To accomplish these aims, methods from the Scottish Intercollegiate Guideline Network
      • Scottish Intercollegiate Guidelines Network
      Annex B: key to evidence statements and grades of recommendations. In: SIGN 50: A Guideline Developer's Handbook. 2008 edition, revised 2011. Edinburgh, Scotland: Scottish Intercollegiate Guidelines Network.
      (SIGN) and the Grading of Recommendations Assessment, Development and Evaluation
      • Guyatt GH
      • Oxman AD
      • Vist GE
      • et al.
      GRADE: an emerging consensus on rating quality of evidence and strength of recommendations.
      (GRADE) group are used. GRADE is a systematic approach to grading the strength of the total body of evidence that is available to support recommendations on a specific clinical management issue. Organizations that have adopted GRADE include SIGN, the World Health Organization, the Agency for Healthcare Research and Quality, and the American College of Physicians.
      • GRADE Working Group
      Organizations that have endorsed or that are using GRADE.
      • All studies used to form a recommendation for care are graded for strength of evidence individually, and that grade is listed with the study citation.
      • Tabled 1
        I++High-quality meta-analyses, systematic reviews of randomized controlled trials (RCTs), or RCTs with a very low risk of bias
        I+Well-conducted meta-analyses, systematic reviews of RCTs, or RCTs with a low risk of bias
        I-Meta-analyses, systematic reviews of RCTs, or RCTs with a high risk of bias
        II++
        • High-quality systematic reviews of case-control or cohort studies
        • High-quality case-control or cohort studies with a very low risk of confounding or bias and a high probability that the relationship is causal
        II+Well-conducted case-control or cohort studies with a low risk of confounding or bias and a moderate probability that the relationship is causal
        II-Case-control or cohort studies with a high risk of confounding or bias and a significant risk that the relationship is not causal
        IIINonanalytic studies (e.g., case reports, case series)
      • Tabled 1
        Good qualityFurther research is very unlikely to change our confidence in the estimate of effect
        Moderate qualityFurther research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate
        Insufficient qualityFurther research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate Any estimate of effect is very uncertain
      • Tabled 1
        Strong recommendationUsed when the desirable effects of an intervention clearly outweigh the undesirable effects or clearly do not
        Discretionary recommendationUsed when the trade-offs are less certain—either because of low-quality evidence or because evidence suggests that desirable and undesirable effects are closely balanced
      • The Highlighted Findings and Recommendations for Care section lists points determined by the PPP Panel to be of particular importance to vision and quality of life outcomes.
      • All recommendations for care in this PPP were rated using the system described above. Ratings are embedded throughout the PPP main text in italics.
      • Literature searches to update the PPP were undertaken in March 2016 in the PubMed and Cochrane databases. Complete details of the literature searches are available on www.aao.org/ppp.

       HIGHLIGHTED FINDINGS & RECOMMENDATIONS FOR CARE

      Strabismus in children under 4 months of age sometimes resolves, particularly if the deviation is intermittent, variable, or measures less than 40 prism diopters.
      Repeat cycloplegic refraction is indicated when esotropia does not respond to the initial prescription of hyperopic refraction or when the esotropia recurs after surgery.
      Bilateral lateral rectus recession and unilateral recess-resect are both reasonable strategies for initial surgery of intermittent exotropia.
      Young children with intermittent exotropia and good fusional control can be followed without surgery because there is a low rate of deterioration to constant exotropia or reduced stereopsis.
      Children with untreated strabismus can have reduced binocular potential and impaired social interactions, which may affect their interactions and quality of life.
      Simultaneous prism and cover testing, which measures the manifest angle of strabismus, and prism and alternate cover testing, which measures the total angle of misalignment, are important elements of binocular testing. Both inform the ophthalmologist's decisions regarding management and surgical indications.
      Convergence insufficiency occurs in children and adults, and symptoms with near viewing (typically reading) can often be improved using vergence exercises.

       Section I. Esotropia

       INTRODUCTION

       DISEASE DEFINITION

      Strabismus describes any binocular misalignment. The most common types are esotropia (inward deviation) and exotropia (outward deviation). Esotropia is a convergent misalignment of the visual axes. The scope of this section is limited to the nonparalytic, nonrestrictive form of the disease with onset in childhood and with minimal or no limitation in range of motion of the eyes.
      Esotropia can be categorized in a variety of ways, usually based on age of onset or underlying causes:
      • Infantile esotropia
      • Acquired esotropia
        • Accommodative esotropia
          • Accommodative refractive esotropia
          • Accommodative refractive esotropia with a high accommodative convergence to accommodation ratio (AC/A)
          • Accommodative nonrefractive esotropia with a high AC/A ratio
        • Partially accommodative esotropia
        • Nonaccommodative esotropia
      • Other

       Infantile Esotropia

      Infantile esotropia presents before age 6 months.
      • Mohney BG
      Common forms of childhood esotropia.
      Intermittent esotropia during the first 3 months of life
      • Archer SM
      • Sondhi N
      • Helveston EM
      Strabismus in infancy.
      • Horwood AM
      Maternal observations of ocular alignment in infants.
      • Nixon RB
      • Helveston EM
      • Miller K
      • et al.
      Incidence of strabismus in neonates.
      • Sondhi N
      • Archer SM
      • Helveston EM
      Development of normal ocular alignment.
      • Thorn F
      • Gwiazda J
      • Cruz AA
      • et al.
      The development of eye alignment, convergence, and sensory binocularity in young infants.
      • Pediatric Eye Disease Investigator Group
      The clinical spectrum of early-onset esotropia: experience of the Congenital Esotropia Observational Study.
      • Pediatric Eye Disease Investigator Group
      Spontaneous resolution of early-onset esotropia: experience of the Congenital Esotropia Observational Study.
      may occur and does not necessarily predict the development of constant strabismus. Simultaneous prism and cover testing, and prism and alternate cover testing are important elements of binocular testing. Children with infantile esotropia are at risk for amblyopia, although the presence of cross-fixation may diminish this risk. Characteristics of infantile esotropia include the following:
      • Onset before the age of 6 months without spontaneous resolution
      • Nonaccommodative or partially accommodative etiology
      • Constant angle of deviation that may increase with time
        • Pediatric Eye Disease Investigator Group
        Instability of ocular alignment in childhood esotropia.
      • Frequent cross-fixation with the fixing eye in adduction
      • Abnormal binocular visual function
      Additional features that may not be present at the time of diagnosis include latent or manifest latent nystagmus (see Detection of Nystagmus section under Examination), dissociated vertical deviation, oblique muscle dysfunction, A or V patterns, and optokinetic nystagmus asymmetry for nasal versus temporal pursuit.

       Acquired Esotropia

      Acquired forms of esotropia typically develop after age 6 months and may be accommodative, partially accommodative, or nonaccommodative. These children are at risk for amblyopia.
      • Berk AT
      • Kocak N
      • Ellidokuz H
      Treatment outcomes in refractive accommodative esotropia.

       Accommodative Esotropia

      Characteristics of accommodative esotropia include:
      The etiology is usually related to excessive convergence in a child with bilateral hyperopia (usually more than 2.00 diopters [D]), correction of which eliminates the esotropia (accommodative refractive esotropia). Sometimes correction of the hyperopia results in normal alignment at distance fixation but a persistent esotropia at near (accommodative refractive esotropia with a high AC/A ratio). Less frequently, children have normal alignment at distance fixation with no significant hyperopia, but they develop a constant or intermittent esotropia with near fixation (accommodative nonrefractive esotropia with a high AC/A ratio).

       Partially Accommodative Esotropia

      Children with acquired partially accommodative esotropia experience some improvement of their esotropia when they wear corrective lenses for their hyperopia.

       Nonaccommodative Esotropia

      Children with nonaccommodative esotropia have an acquired esotropia that is approximately equal in amount at distance and near fixation and have either no significant refractive error or no improvement in the angle of esotropia with correction of refractive error. If onset is acute, especially if associated with diplopia, neuroimaging should be considered.

       Other

      A differential diagnosis of childhood esotropia includes cranial nerve VI palsy, esotropic Duane syndrome, sensory esotropia, restrictive esotropia, consecutive esotropia, and nystagmus blockage syndrome (see Detection of Nystagmus section). Discussion of these entities is outside the scope of this PPP.

       PATIENT POPULATION

      Children with esotropia.

       CLINICAL OBJECTIVES

      • Identify children at risk for esotropia
      • Detect esotropia
      • Detect and treat amblyopia that may cause, or be caused by, esotropia (see Amblyopia PPP
        • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
        Preferred Practice Pattern®. Amblyopia.
        )
      • Educate the patient and/or family caregiver, as appropriate
      • Inform the patient's other health providers of the diagnosis and treatment plan
      • Treat the esotropia (align the visual axes) to promote and maintain binocular vision (fusion, stereopsis), prevent amblyopia or facilitate its treatment, and restore normal appearance
      • Maximize quality of life by optimizing binocular alignment and visual acuity
      • Monitor vision and binocular alignment, and modify therapy as appropriate

       BACKGROUND

       PREVALENCE AND RISK FACTORS

      Prevalence estimates of strabismus range from 0.8% to 6.8% in different populations.
      • Bardisi WM
      • Bin Sadiq BM
      Vision screening of preschool children in Jeddah, Saudi Arabia.
      • Donnelly UM
      • Stewart NM
      • Hollinger M
      Prevalence and outcomes of childhood visual disorders.
      • Kvarnstrom G
      • Jakobsson P
      • Lennerstrand G
      Visual screening of Swedish children: an ophthalmological evaluation.
      • Matsuo T
      • Matsuo C
      The prevalence of strabismus and amblyopia in Japanese elementary school children.
      • Ohlsson J
      • Villarreal G
      • Sjostrom A
      • et al.
      Visual acuity, residual amblyopia and ocular pathology in a screened population of 12-13-year-old children in Sweden.
      • Robaei D
      • Rose KA
      • Kifley A
      • et al.
      Factors associated with childhood strabismus: findings from a population-based study.
      • Tananuvat N
      • Manassakorn A
      • Worapong A
      • et al.
      Vision screening in schoolchildren: two years results.
      Multi-ethnic Pediatric Eye Disease Study Group
      Prevalence of amblyopia and strabismus in African American and Hispanic children ages 6 to 72 months: the Multi-ethnic Pediatric Eye Disease Study.
      • Friedman DS
      • Repka MX
      • Katz J
      • et al.
      Prevalence of amblyopia and strabismus in white and African American children aged 6 through 71 months: the Baltimore Pediatric Eye Disease Study.
      • Chia A
      • Lin X
      • Dirani M
      • et al.
      Risk factors for strabismus and amblyopia in young Singapore Chinese children.
      Multi-Ethnic Pediatric Eye Disease Study Group
      Prevalence of amblyopia or strabismus in Asian and non-Hispanic white preschool children: Multi-Ethnic Pediatric Eye Disease Study.
      • Caca I
      • Cingu AK
      • Sahin A
      • et al.
      Amblyopia and refractive errors among school-aged children with low socioeconomic status in southeastern Turkey.
      • Fu J
      • Li SM
      • Liu LR
      • et al.
      Prevalence of amblyopia and strabismus in a population of 7th-grade junior high school students in Central China: the Anyang Childhood Eye Study (ACES).
      • Oscar A
      • Cherninkova S
      • Haykin V
      • et al.
      Amblyopia screening in Bulgaria.
      • Lanca C
      • Serra H
      • Prista J
      Strabismus, visual acuity, and uncorrected refractive error in Portuguese children aged 6 to 11 years.
      • Lin S
      • Congdon N
      • Yam JC
      • et al.
      Alcohol use and positive screening results for depression and anxiety are highly prevalent among Chinese children with strabismus.
      In the United States, esotropia and exotropia have similar prevalence rates, whereas in Ireland esotropia has been reported five times more frequently than exotropia, and in Australia esotropia has been reported to be twice as frequent as exotropia.
      Multi-ethnic Pediatric Eye Disease Study Group
      Prevalence of amblyopia and strabismus in African American and Hispanic children ages 6 to 72 months: the Multi-ethnic Pediatric Eye Disease Study.
      Multi-Ethnic Pediatric Eye Disease Study Group
      Prevalence of amblyopia or strabismus in Asian and non-Hispanic white preschool children: Multi-Ethnic Pediatric Eye Disease Study.
      Joint Writing Committee for the Multi-Ethnic Pediatric Eye Disease Study and the Baltimore Pediatric Eye Disease Study Groups
      Risk factors associated with childhood strabismus: the Multi-Ethnic Pediatric Eye Disease and Baltimore Pediatric Eye Disease Studies.
      In Hong Kong, Singapore, Japan, and China, however, exotropia is more frequent than esotropia.
      • Matsuo T
      • Matsuo C
      The prevalence of strabismus and amblyopia in Japanese elementary school children.
      • Chia A
      • Lin X
      • Dirani M
      • et al.
      Risk factors for strabismus and amblyopia in young Singapore Chinese children.
      • Fu J
      • Li SM
      • Liu LR
      • et al.
      Prevalence of amblyopia and strabismus in a population of 7th-grade junior high school students in Central China: the Anyang Childhood Eye Study (ACES).
      • Lin S
      • Congdon N
      • Yam JC
      • et al.
      Alcohol use and positive screening results for depression and anxiety are highly prevalent among Chinese children with strabismus.
      • Yu CB
      • Fan DS
      • Wong VW
      • et al.
      Changing patterns of strabismus: a decade of experience in Hong Kong.
      Children with esotropia are at risk for amblyopia.
      • Birch EE
      • Stager DR
      Monocular acuity and stereopsis in infantile esotropia.
      • Dickey CF
      • Metz HS
      • Stewart SA
      • Scott WE
      The diagnosis of amblyopia in cross-fixation.
      Children are at higher risk to develop strabismus if anisometropia and/or hyperopia are present, and they are at a greater risk to develop esotropia as hyperopia increases.
      Joint Writing Committee for the Multi-Ethnic Pediatric Eye Disease Study and the Baltimore Pediatric Eye Disease Study Groups
      Risk factors associated with childhood strabismus: the Multi-Ethnic Pediatric Eye Disease and Baltimore Pediatric Eye Disease Studies.
      • Dobson V
      • Sebris SL
      Longitudinal study of acuity and stereopsis in infants with or at-risk for esotropia.
      • O'Connor AR
      • Stephenson TJ
      • Johnson A
      • et al.
      Strabismus in children of birth weight less than 1701 g.
      Other at-risk groups include children who are neurodevelopmentally impaired;
      • Cregg M
      • Woodhouse JM
      • Stewart RE
      • et al.
      Development of refractive error and strabismus in children with Down syndrome.
      • Haugen OH
      • Hovding G
      Strabismus and binocular function in children with Down syndrome. A population-based, longitudinal study.
      • Pennefather PM
      • Tin W
      Ocular abnormalities associated with cerebral palsy after preterm birth.
      • Wong V
      • Ho D
      Ocular abnormalities in Down syndrome: an analysis of 140 Chinese children.
      were born prematurely;
      • Coats DK
      • Avilla CW
      • Paysse EA
      • et al.
      Early-onset refractive accommodative esotropia.
      • Repka MX
      • Summers CG
      • Palmer EA
      • Cryotherapy for Retinopathy of Prematurity Cooperative Group
      • et al.
      The incidence of ophthalmologic interventions in children with birth weights less than 1251 grams: results through 5 1/2 years.
      had low birth weight;
      • Pennefather PM
      • Clarke MP
      • Strong NP
      • et al.
      Risk factors for strabismus in children born before 32 weeks' gestation.
      • Holmstrom G
      • el Azazi M
      • Kugelberg U
      Ophthalmological follow up of preterm infants: a population based, prospective study of visual acuity and strabismus.
      had low Apgar scores;
      • Mohney BG
      • Erie JC
      • Hodge DO
      • Jacobsen SJ
      Congenital esotropia in Olmsted County, Minnesota.
      have craniofacial or chromosomal anomalies;
      • Mohney BG
      • Erie JC
      • Hodge DO
      • Jacobsen SJ
      Congenital esotropia in Olmsted County, Minnesota.
      • Khan SH
      • Nischal KK
      • Dean F
      • et al.
      Visual outcomes and amblyogenic risk factors in craniosynostotic syndromes: a review of 141 cases.
      • Khong JJ
      • Anderson P
      • Gray TL
      • et al.
      Ophthalmic findings in apert syndrome prior to craniofacial surgery.
      • Creavin AL
      • Brown RD
      Ophthalmic abnormalities in children with Down syndrome.
      were exposed to smoking
      Joint Writing Committee for the Multi-Ethnic Pediatric Eye Disease Study and the Baltimore Pediatric Eye Disease Study Groups
      Risk factors associated with childhood strabismus: the Multi-Ethnic Pediatric Eye Disease and Baltimore Pediatric Eye Disease Studies.
      or alcohol in utero;
      • Bruce BB
      • Biousse V
      • Dean AL
      • Newman NJ
      Neurologic and ophthalmic manifestations of fetal alcohol syndrome.
      or have a family history of strabismus.
      • Nixon RB
      • Helveston EM
      • Miller K
      • et al.
      Incidence of strabismus in neonates.
      • Abrahamsson M
      • Magnusson G
      • Sjostrand J
      Inheritance of strabismus and the gain of using heredity to determine populations at risk of developing strabismus.
      • Coats DK
      • Demmler GJ
      • Paysse EA
      • et al.
      Ophthalmologic findings in children with congenital cytomegalovirus infection.
      • Swan KC
      Accommodative esotropia long range follow-up.
      The prevalence of esotropia increases with older age (e.g., higher prevalence at 4 to 6 years compared with 6 to 11 months), moderate anisometropia, and moderate amounts of hyperopia.
      • Friedman DS
      • Repka MX
      • Katz J
      • et al.
      Prevalence of amblyopia and strabismus in white and African American children aged 6 through 71 months: the Baltimore Pediatric Eye Disease Study.
      Joint Writing Committee for the Multi-Ethnic Pediatric Eye Disease Study and the Baltimore Pediatric Eye Disease Study Groups
      Risk factors associated with childhood strabismus: the Multi-Ethnic Pediatric Eye Disease and Baltimore Pediatric Eye Disease Studies.
      In some families, a Mendelian inheritance pattern has been observed.
      • Maumenee IH
      • Alston A
      • Mets MB
      • et al.
      Inheritance of congenital esotropia.
      A large study of mono- and dizygotic twins found evidence of heritability for esodeviation, whereas no such association was found for exodeviation.
      • Sanfilippo PG
      • Hammond CJ
      • Staffieri SE
      • et al.
      Heritability of strabismus: genetic influence is specific to eso-deviation and independent of refractive error.
      The incidence of strabismus is related to premature births
      • Gulati S
      • Andrews CA
      • Apkarian AO
      • et al.
      Effect of gestational age and birth weight on the risk of strabismus among premature infants.
      and perinatal morbidity, genetic disorders, and detrimental prenatal environmental influences, such as substance abuse
      • Spiteri Cornish K
      • Hrabovsky M
      • Scott NW
      • et al.
      The short- and long-term effects on the visual system of children following exposure to maternal substance misuse in pregnancy.
      and smoking.
      Joint Writing Committee for the Multi-Ethnic Pediatric Eye Disease Study and the Baltimore Pediatric Eye Disease Study Groups
      Risk factors associated with childhood strabismus: the Multi-Ethnic Pediatric Eye Disease and Baltimore Pediatric Eye Disease Studies.
      • Mohney BG
      • Erie JC
      • Hodge DO
      • Jacobsen SJ
      Congenital esotropia in Olmsted County, Minnesota.
      • Bruce BB
      • Biousse V
      • Dean AL
      • Newman NJ
      Neurologic and ophthalmic manifestations of fetal alcohol syndrome.
      • Chew E
      • Remaley NA
      • Tamboli A
      • et al.
      Risk factors for esotropia and exotropia.
      • Podgor MJ
      • Remaley NA
      • Chew E
      Associations between siblings for esotropia and exotropia.
      • Gill AC
      • Oei J
      • Lewis NL
      • et al.
      Strabismus in infants of opiate-dependent mothers.
      One study looked at effect of gestational age and birth weight in premature infants and found that very low birth weight (<2000 g) conferred a large increase of risk of strabismus.
      • Gulati S
      • Andrews CA
      • Apkarian AO
      • et al.
      Effect of gestational age and birth weight on the risk of strabismus among premature infants.
      There was no association with gestational age after controlling for birth weight, although the two factors are highly correlated. In the long term, reduction or prevention of those factors could result in a decrease in the incidence of infantile esotropia.

       NATURAL HISTORY

      Infantile esotropia, characterized as a constant esodeviation presenting before 6 months of age, is unlikely to resolve. However, some children in this age group who have esotropia that is intermittent or variable, or that measures less than 40 prism diopters, may have resolution of their esotropia by age 1 year.
      • Pediatric Eye Disease Investigator Group
      Spontaneous resolution of early-onset esotropia: experience of the Congenital Esotropia Observational Study.
      • Robb RM
      • Rodier DW
      The variable clinical characteristics and course of early infantile esotropia.
      • Birch E
      • Stager D
      • Wright K
      • Beck R
      • Pediatric Eye Disease Investigator Group
      The natural history of infantile esotropia during the first six months of life.
      Because children with intermittent esotropia have normal alignment at least part of the time, the risk of abnormal binocularity is reduced.
      Acquired esotropia is more frequent than infantile esotropia
      • Greenberg AE
      • Mohney BG
      • Diehl NN
      • Burke JP
      Incidence and types of childhood esotropia: a population-based study.
      and usually presents between the ages of 1 year and 8 years.
      • Mohney BG
      Common forms of childhood esotropia.
      Onset of accommodative esotropia as early as 2 months of age has been reported.
      • Mohney BG
      Common forms of childhood esotropia.
      • Baker JD
      • Parks MM
      Early-onset accommodative esotropia.
      • Pollard ZF
      Accommodative esotropia during the first year of life.
      • Coats DK
      • Avilla CW
      • Paysse EA
      • et al.
      Early-onset refractive accommodative esotropia.
      Children with very early onset accommodative esotropia are more likely to require extraocular muscle surgery despite correction of their refractive error with eyeglasses.
      • Coats DK
      • Avilla CW
      • Paysse EA
      • et al.
      Early-onset refractive accommodative esotropia.
      • Dickey CF
      • Scott WE
      The deterioration of accommodative esotropia: frequency, characteristics, and predictive factors.
      Accommodative forms of esotropia may begin as an intermittent deviation associated with fatigue, illness, or near viewing. Because younger children lose binocular vision rapidly, correcting the hyperopic refractive error as quickly as possible is advised.
      • Wilson ME
      • Bluestein EC
      • Parks MM
      Binocularity in accommodative esotropia.

       RATIONALE FOR TREATMENT

      The potential benefits of treatment for esotropia include promoting binocular vision and normal visual function in each eye.
      • Ing MR
      Early surgical alignment for congenital esotropia.
      • Bateman JB
      • Parks MM
      • Wheeler N
      Discriminant analysis of congenital esotropia surgery. Predictor variables for short- and long-term outcomes.
      • Rogers GL
      • Bremer DL
      • Leguire LE
      • Fellows RR
      Clinical assessment of visual function in the young child: a prospective study of binocular vision.
      • von Noorden GK
      A reassessment of infantile esotropia. XLIV Edward Jackson memorial lecture.
      If binocularity is achieved, the number of surgical procedures over a lifetime and overall cost to society may be reduced.
      • Arthur BW
      • Smith JT
      • Scott WE
      Long-term stability of alignment in the monofixation syndrome.
      • Birch EE
      • Fawcett S
      • Stager DR
      Why does early surgical alignment improve stereoacuity outcomes in infantile esotropia?.
      Fusion and stereopsis are necessary for some careers and may be useful in many activities, such as athletics and activities of daily life.
      • Rogers GL
      • Chazan S
      • Fellows R
      • Tsou BH
      Strabismus surgery and its effect upon infant development in congenital esotropia.
      • Kushner BJ
      Binocular field expansion in adults after surgery for esotropia.
      • Tolchin JG
      • Lederman ME
      Congenital (infantile) esotropia: psychiatric aspects.
      • Satterfield D
      • Keltner JL
      • Morrison TL
      Psychosocial aspects of strabismus study.
      The appearance of crossed eyes may reduce employment opportunities.
      • Satterfield D
      • Keltner JL
      • Morrison TL
      Psychosocial aspects of strabismus study.
      • Burke JP
      • Leach CM
      • Davis H
      Psychosocial implications of strabismus surgery in adults.
      • Coats DK
      • Paysse EA
      • Towler AJ
      • Dipboye RL
      Impact of large angle horizontal strabismus on ability to obtain employment.
      In addition, binocular alignment is important for the development of a positive self-image and enhances social interactions by normalizing appearance as well as eye contact.
      • Rogers GL
      • Chazan S
      • Fellows R
      • Tsou BH
      Strabismus surgery and its effect upon infant development in congenital esotropia.
      • Tolchin JG
      • Lederman ME
      Congenital (infantile) esotropia: psychiatric aspects.
      • Satterfield D
      • Keltner JL
      • Morrison TL
      Psychosocial aspects of strabismus study.
      • Johns HA
      • Manny RE
      • Fern KD
      • Hu YS
      The effect of strabismus on a young child's selection of a playmate.
      • Uretmen O
      • Egrilmez S
      • Kose S
      • et al.
      Negative social bias against children with strabismus.
      • Sabri K
      • Knapp CM
      • Thompson JR
      • Gottlob I
      The VF-14 and psychological impact of amblyopia and strabismus.
      • Mojon-Azzi SM
      • Kunz A
      • Mojon DS
      Strabismus and discrimination in children: are children with strabismus invited to fewer birthday parties?.
      In one study, children aged 5 years and older expressed a negative feeling about dolls that had been altered to be esotropic or exotropic.
      • Paysse EA
      • Steele EA
      • McCreery KM
      • et al.
      Age of the emergence of negative attitudes toward strabismus.
      In another study, elementary school teachers rated personal characteristics of children with esotropia and exotropia more negatively than orthotropic children.
      • Uretmen O
      • Egrilmez S
      • Kose S
      • et al.
      Negative social bias against children with strabismus.
      In a sample of children enrolled in the Multiethnic Pediatric Eye Disease Study, strabismus was associated with a decreased general health-related quality of life in preschool children, based on the parents' proxy reporting.
      • Wen G
      • McKean-Cowdin R
      • Varma R
      • et al.
      General health-related quality of life in preschool children with strabismus or amblyopia.

       CARE PROCESS

       PATIENT OUTCOME CRITERIA

      • Optimal binocular motor alignment
      • Optimal binocular sensory status (fusion and stereopsis)
      • Optimal visual acuity in each eye

       DIAGNOSIS

      The purpose of the comprehensive strabismus evaluation is to make the diagnosis, establish baseline status, and determine appropriate initial therapy. The possibility of restrictive, paralytic, or other neurologic causes (especially head trauma or increased intracranial pressure) for strabismus should be considered. Because binocular vision can degrade rapidly in young children, resulting in suppression and anomalous retinal correspondence, early diagnosis and treatment are essential.
      • Dickey CF
      • Scott WE
      The deterioration of accommodative esotropia: frequency, characteristics, and predictive factors.
      • Wilson ME
      • Bluestein EC
      • Parks MM
      Binocularity in accommodative esotropia.
      • Fawcett S
      • Leffler J
      • Birch EE
      Factors influencing stereoacuity in accommodative esotropia.
      The examination of a patient who has childhood-onset strabismus includes all elements of the comprehensive ophthalmic examination in addition to sensory, motor, refractive, and accommodative testing.
      • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
      Preferred Practice Pattern®. Pediatric Eye Evaluations.
      • Feder RS
      • Olsen TW
      • Prum Jr., BE
      • et al.
      Comprehensive Adult Medical Eye Evaluation Preferred Practice Pattern® Guidelines.

       History

      Although a thorough history generally includes the following items, the details depend on the patient's particular problems and needs.
      • Demographic data, including gender, date of birth, and identity of parent/caregiver
      • Documentation of identity and relationship of historian
      • Identity of other pertinent health care providers
      • The chief complaint and reason for the eye evaluation, including date of onset and frequency of the ocular misalignment; which eye is deviated and in what direction; and the presence or absence of diplopia, squinting, closing one eye, or other visual symptoms. Review of photographs of the patient may be helpful.
      • Ocular history, including other eye problems, injuries, diseases, surgery, and treatments (including eyeglasses and/or amblyopia therapy)
      • Systemic history, birth weight, gestational age, prenatal and perinatal history that may be pertinent (e.g., alcohol, drug, and tobacco use during pregnancy), past hospitalizations and operations, and general health and development
      • Pertinent review of systems, including history of head trauma and relevant systemic diseases
      • Current medications and allergies
      • Family history, including eye conditions (strabismus, amblyopia, type of eyeglasses and history of wear, extraocular muscle surgery or other eye surgery, and genetic diseases)
      • Social history (e.g., grade level in school, learning difficulties, behavior problems, or issues with social interactions)

       Examination

      The comprehensive strabismus examination should include the following elements:
      • Verification of eyeglass correction with a lensometer
      • Binocular alignment at distance and near in primary gaze, up and down gaze, and horizontal gaze positions, if possible; if eyeglasses are worn, alignment testing should be performed with correction; alignment testing without correction may also be appropriate in some circumstances
      • Extraocular muscle function (ductions and versions, including incomitance such as found in some A and V patterns (see Extraocular Muscle Function section)
      • Detection of latent or manifest nystagmus
      • Sensory testing, including fusion and stereoacuity
      • Cycloplegic retinoscopy/refraction
      • Funduscopic examination
      • Additional testing, such as monocular and binocular optokinetic nystagmus testing for nasal-temporal pursuit asymmetry associated with infantile esotropia
      Documenting the child's level of cooperation with the examination can be useful in interpreting the results and in making comparisons among examinations over time.
      For details on visual acuity, assessment of fixation pattern, and visual field testing, refer to the
      Pediatric Eye Evaluations PPP, Section II. Comprehensive Ophthalmic Examination.
      • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
      Preferred Practice Pattern®. Pediatric Eye Evaluations.

       Binocular Alignment and Motility

      Binocular alignment can be evaluated using a variety of clinical methods. When possible, a target that controls the patient's accommodation should be used for both distant and near fixation during assessment of alignment. The method of measuring the angle of esotropia and the presence or absence of refractive correction should be documented. If the patient is unable to participate in more sophisticated testing, the angle may be estimated using the corneal light-reflection test with or without prisms or by estimating the amount of eye movement required to refixate with alternate-cover testing without prism. The prism and alternate-cover test measures the total deviation and, as such, is used to quantify the amount of surgery required.
      • Choi RY
      • Kushner BJ
      The accuracy of experienced strabismologists using the Hirschberg and Krimsky tests.
      The simultaneous prism-and-cover test measures the manifest deviation and provides useful information for patients with fusional vergences, where the alignment under binocular viewing conditions is better than during alternate-cover testing (e.g., monofixation syndrome). The simultaneous prism-and-cover test is used by many surgeons as a means of determining if strabismus surgery is indicated.

       Extraocular Muscle Function

      The examiner should evaluate versions (binocular motility) and ductions (monocular motility) and note any limitation, overaction, or incomitance (change in the angle of strabismus in different gaze positions). When versions are limited, full abduction on monocular duction testing can distinguish the child with infantile or accommodative esotropia from a child with paretic or restrictive esotropia, or esotropic Duane syndrome. Monocular occlusion and oculocephalic rotations (the “doll's-head maneuver” or vestibuloocular reflex) are particularly valuable in infants and young children and often reveal clinically normal ductions that may not otherwise be documented. Oblique muscle dysfunction, A or V patterns, and/or dissociated vertical or horizontal deviations should be documented. Diseases associated with paresis, paralysis, or restriction of the extraocular muscles are not in the scope of this PPP.

       Detection of Nystagmus

      Nystagmus in the patient with esotropia may be manifest, latent, or manifest-latent. Nystagmus is more common in patients with earlier-onset strabismus than in those with later onset strabismus. Manifest nystagmus is present constantly and may be horizontal, vertical, and/or torsional. It is typically symmetrical, although it may vary in magnitude, speed, and wave form, depending on the direction of gaze and other specific viewing conditions. Latent nystagmus (also known as occlusion nystagmus) is conjugate, and it is characterized by horizontal jerk oscillations of the eyes that are seen under monocular viewing conditions. It is the only form of nystagmus that reverses direction with a change in fixation. Latent nystagmus is characterized by a slow nasal drift of the fixating eye, followed by saccadic refixation. The nystagmus is described as latent because it is seen when one eye is occluded. Manifest-latent nystagmus has an identical waveform as latent nystagmus but is evident under binocular viewing conditions, and its amplitude increases with monocular occlusion. Children with manifest-latent nystagmus often present with a head turn and hold the fixating eye in adduction. Although esotropia and nystagmus often coexist in infantile esotropia, it must be distinguished from nystagmus blockage syndrome in which children with infantile esotropia use excessive convergence to damp the amplitude of nystagmus. In these children, the magnitude of the esotropia seems to increase with prism neutralization of the deviation.

       Sensory Testing

      When feasible, the child's binocular sensory status should be assessed using Worth 4-Dot Testing and stereoacuity tests. Reliable data may be difficult to obtain in younger children.
      • Schmidt P
      • Maguire M
      • Kulp MT
      • et al.
      Random Dot E stereotest: testability and reliability in 3- to 5-year-old children.
      In the older strabismic (especially esotropic) patient, more detailed sensory testing is occasionally useful, especially if there is a history of diplopia. Sensory testing should be done before a patch or occluder dissociates the child's binocular status. An orthoptic evaluation, which should include Bagolini lenses, afterimage testing, and synoptophore testing, may further define the sensorimotor status of the child.
      Stereopsis occurs when the two slightly disparate images from the two eyes are cortically integrated. Many tests are available to determine stereopsis, including the Stereo Fly Test, the Randot Test, the Random-Dot E Test, the TNO Test, the Frisby Test, and the Lang Stereopsis Test.
      The Worth 4-Dot Test can assess peripheral or central fusion. When testing at near, the patient wears the red-green eyeglasses and looks at a target with four lights (two green, one red, and one white). If the patient sees four lights, it indicates peripheral fusion. Two or three lights indicate monocular suppression, and five lights seen simultaneously indicate diplopia. Some patients with alternating monocular suppression may report five lights, though not all five are seen at once. The Worth 4-Dot target tests central fusion at distance and peripheral fusion at near.

       Cycloplegic Retinoscopy/Refraction

      Determination of refractive errors is important in the diagnosis and treatment of amblyopia or strabismus. Patients should undergo cycloplegic refraction with retinoscopy and subjective refinement when possible.
      American Academy of Ophthalmology Basic and Clinical Science Course Subcommittee
      Basic and Clinical Science Course. Pediatric Ophthalmology and Strabismus: Section 6, 2016-2017.
      Dynamic retinoscopy done prior to cycloplegia provides a rapid assessment of accommodation and may be helpful in evaluating a child with asthenopia who has high hyperopia or the child with accommodative insufficiency.
      • Guyton DL
      • O'Connor GM
      Dynamic retinoscopy.
      • Hunter DG
      Dynamic retinoscopy: the missing data.
      With this technique, the examiner evaluates the change in the retinoscopic reflex from a “with” motion toward neutrality when the patient shifts fixation from distance to a small target on the retinoscope.
      Adequate cycloplegia is necessary for accurate retinoscopy in children because of their increased accommodative tone compared with adults. At present, there is no ideal cycloplegic that is safe, has rapid onset and recovery, provides sufficient cycloplegia, and has no local or systemic side effects.
      • Fan DS
      • Rao SK
      • Ng JS
      • et al.
      Comparative study on the safety and efficacy of different cycloplegic agents in children with darkly pigmented irides.
      For details of cycloplegic eye drops, refer to the Pediatric Eye Evaluation PPP, Section II. Comprehensive Ophthalmic Examination.
      • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
      Preferred Practice Pattern®. Pediatric Eye Evaluations.

       Funduscopic Examination

      Retinal or optic nerve abnormalities may be present in children with esotropia, in some cases producing sensory strabismus. Particular attention should be paid to the optic nerve for signs of swelling, pallor, or congenital anomalies. In addition, nasal or temporal displacement of the macula may give rise to pseudostrabismus (the appearance of strabismus when there is no shift by alternate-cover testing in the presence of good fixation). Temporal displacement of the macula (most often seen in patients with retinopathy of prematurity) may cause a positive angle kappa, with nasal displacement of the corneal light reflection. This can simulate exotropia in a child with aligned eyes or mask the strabismus in a child with esotropia.
      American Academy of Ophthalmology Basic and Clinical Science Course Subcommittee
      Basic and Clinical Science Course. Pediatric Ophthalmology and Strabismus: Section 6, 2016-2017.
      A negative angle kappa is seen less frequently and is usually associated with high myopia.

       Additional Testing

      Forced duction and/or force generation tests may be useful if there is incomitance or other evidence of extraocular muscle restriction, or if paresis/paralysis is suspected. Generally, such testing in young children is not feasible as an office procedure. Many ophthalmologists perform forced duction testing routinely at the beginning of extraocular muscle surgery when the child is anesthetized. Detection of mechanical restriction may influence the surgical plan.

       MANAGEMENT

       Prevention

      There is consensus that early detection and prompt management of strabismus and potential amblyogenic factors improve long-term visual and sensorimotor outcomes.
      For children without esotropia, the threshold of hyperopia that requires treatment has not been established, but correction of hyperopia may reduce the risk of developing accommodative esotropia and/or amblyopia.
      • Edelman PM
      • Borchert MS
      Visual outcome in high hypermetropia.
      • Werner DB
      • Scott WE
      Amblyopia case reports–bilateral hypermetropic ametropic amblyopia.
      • Colburn JD
      • Morrison DG
      • Estes RL
      • et al.
      Longitudinal follow-up of hypermetropic children identified during preschool vision screening.
      • Jones-Jordan L
      • Wang X
      • Scherer RW
      • Mutti DO
      Spectacle correction versus no spectacles for prevention of strabismus in hyperopic children.
      (Refer to Table 3 in the Pediatric Eye Evaluations PPP, Section II. Comprehensive Ophthalmic Examination, for guidelines for correcting hyperopia in children.
      • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
      Preferred Practice Pattern®. Pediatric Eye Evaluations.
      ) For children with esotropia, the threshold for prescribing hyperopic eyeglasses is lower than for children without esotropia. For example, eyeglasses are generally prescribed for +2.00 diopters (D) or more in children under 2 years of age, and +1.50 D or more for children over 2. For hyperopic patients, anisometropia is a risk factor for the development of accommodative esotropia.
      • Birch EE
      • Fawcett SL
      • Morale SE
      • et al.
      Risk factors for accommodative esotropia among hypermetropic children.

       Choice of Therapy

      Treatment should be considered for all forms of esotropia, and binocular alignment should be established as soon as possible, especially in young children, to maximize binocular potential,
      • Bateman JB
      • Parks MM
      • Wheeler N
      Discriminant analysis of congenital esotropia surgery. Predictor variables for short- and long-term outcomes.
      • Birch EE
      • Stager Sr., DR
      • Berry P
      • Leffler J
      Stereopsis and long-term stability of alignment in esotropia.
      to prevent or facilitate treatment of amblyopia,
      • Dickey CF
      • Metz HS
      • Stewart SA
      • Scott WE
      The diagnosis of amblyopia in cross-fixation.
      • Sperduto RD
      • Seigel D
      • Roberts J
      • Rowland M
      Prevalence of myopia in the United States.
      and to restore normal appearance. Significant refractive errors should be corrected. Amblyopia treatment is usually started before surgery because this may alter the angle of strabismus
      • Koc F
      • Ozal H
      • Yasar H
      • Firat E
      Resolution in partially accomodative esotropia during occlusion treatment for amblyopia.
      and/or increase the likelihood of good postoperative binocularity.
      • Birch EE
      • Stager Sr., DR
      • Berry P
      • Leffler J
      Stereopsis and long-term stability of alignment in esotropia.
      • Weakley Jr., DR
      • Holland DR
      Effect of ongoing treatment of amblyopia on surgical outcome in esotropia.
      There is evidence that early surgical correction improves sensory outcomes for infantile esotropia, probably because the duration of constant esotropia is minimized.
      • Ing MR
      Early surgical alignment for congenital esotropia.
      • Bateman JB
      • Parks MM
      • Wheeler N
      Discriminant analysis of congenital esotropia surgery. Predictor variables for short- and long-term outcomes.
      • Birch EE
      • Fawcett S
      • Stager DR
      Why does early surgical alignment improve stereoacuity outcomes in infantile esotropia?.
      • Birch EE
      • Stager DR
      • Everett ME
      Random dot stereoacuity following surgical correction of infantile esotropia.
      • Ing MR
      Outcome study of surgical alignment before six months of age for congenital esotropia.
      • Birch EE
      • Stager Sr., DR
      Long-term motor and sensory outcomes after early surgery for infantile esotropia.
      Given equal visual acuity in both eyes, there is no consensus among strabismus surgeons on unilateral versus bilateral surgery, nor is there good evidence supporting one approach over the other.
      • Elliott S
      • Shafiq A
      Interventions for infantile esotropia.
      Treatment for esotropia includes the following:
      • Correction of refractive errors
        • Pediatric Eye Disease Investigator Group
        Spontaneous resolution of early-onset esotropia: experience of the Congenital Esotropia Observational Study.
      • Bifocal eyeglasses
        • Ludwig IH
        • Parks MM
        • Getson PR
        Long-term results of bifocal therapy for accommodative esotropia.
      • Prism therapy
        • Repka MX
        • Connett JE
        • Scott WE
        The one-year surgical outcome after prism adaptation for the management of acquired esotropia.
        • Prism Adaptation Study Research Group
        Efficacy of prism adaptation in the surgical management of acquired esotropia.
      • Amblyopia treatment
        • Weakley Jr., DR
        • Holland DR
        Effect of ongoing treatment of amblyopia on surgical outcome in esotropia.
      • Extraocular muscle surgery
        • Bateman JB
        • Parks MM
        • Wheeler N
        Discriminant analysis of acquired esotropia surgery. Predictor variables for short- and long-term outcomes.
      Treatment plans are formulated in consultation with the parent/caregiver and patient, if appropriate. The plans should be responsive to the preferences and expectations of the parent/caregiver and patient. The plans should account for the parent's/caregiver's and patient's perception of the existing alignment, which may differ from that of the ophthalmologist. It is important that the family/caregiver and ophthalmologist agree on the goals of treatment before surgery is performed. For patients for whom the potential for binocularity is poor, surgery to restore normal appearance may be an appropriate treatment.

       Correction of Refractive Errors

      Correction of significant refractive errors should be the initial treatment for children with esotropia.
      • Coats DK
      • Avilla CW
      • Paysse EA
      • et al.
      Early-onset refractive accommodative esotropia.
      • de Alba Campomanes AG
      • Binenbaum G
      • Campomanes Eguiarte G
      Comparison of botulinum toxin with surgery as primary treatment for infantile esotropia.
      (Refer to Table 3 in the Pediatric Eye Evaluations PPP, Section II. Comprehensive Ophthalmic Examination, for guidelines for correcting refractive errors in children.
      • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
      Preferred Practice Pattern®. Pediatric Eye Evaluations.
      ) For patients with accommodative esotropia, realignment by cycloplegia-determined eyeglasses or contact lenses alone is successful in most cases.
      • Coats DK
      • Avilla CW
      • Paysse EA
      • et al.
      Early-onset refractive accommodative esotropia.
      • Mohney BG
      • Lilley CC
      • Green-Simms AE
      • Diehl NN
      The long-term follow-up of accommodative esotropia in a population-based cohort of children.
      In general, a greater degree of hyperopia indicates a higher likelihood that the refractive error is an important etiologic factor of the esotropia. While children with developmental delay and strabismus may be less tolerant of eyeglasses, they may respond to correction of smaller amounts of ametropia. Additionally, children with a variable angle of esotropia or a greater deviation at near may respond to correction of even low hyperopia.
      The aim of treatment is to correct hyperopia sufficiently to restore alignment, and in most cases a prescription is given to correct the full refractive error as determined after cycloplegia. Undercorrection of the hyperopia sometimes improves eyeglass wear, especially in older children. A manifest noncycloplegic refraction may be required to optimize visual acuity and binocular alignment in older children because correction of the full cycloplegic refractive error may blur their distance vision.
      Improved alignment after prescribing eyeglasses may take several weeks. If the esotropia persists, the cycloplegic refraction should be repeated before considering surgery because additional hyperopic refractive error may be uncovered. A repeat refraction should also be performed for those children initially well aligned in hyperopic eyeglasses who develop recurrent esotropia. Cycloplegia may be used temporarily to facilitate compliance of eyeglass wear. Poor motor and sensory outcomes are likely if eyeglass compliance is poor.
      • Hussein MA
      • Weakley D
      • Wirazka T
      • Paysse EE
      The long-term outcomes in children who are not compliant with spectacle treatment for accommodative esotropia.
      In older children, gradual reduction of the hyperopic correction can be attempted if the deviation is controlled. The effect of such reductions in the hyperopic correction can be simulated in the office setting by placing minus lenses over the eyeglasses to ensure that binocular alignment is optimized while maintaining best-corrected visual acuity.
      In general, eyeglasses to control an esodeviation are well tolerated by children, especially when there is visual improvement. Accurately fitting and properly adjusting the eyeglasses facilitates their acceptance. Head straps or flexible single-piece frames may be useful in infants and young children; cable temples and spring hinges are also helpful. Impact-resistant lenses provide greater safety; they are preferable for children, especially if they are amblyopic, and these lenses are often mandated by state law.

       Bifocals

      An esodeviation greater for near than for distant targets is found in some cases. Convergence excess is defined clinically as a near esodeviation 10 prism diopters or greater than the distance deviation (high clinical AC/A ratio) with the use of full hyperopic correction. Bifocal treatment can be considered in patients with potential for sensory fusion who maintain essentially aligned eyes at distance but have a manifest esotropia at near while wearing their full hyperopic correction. If successful, bifocals may be necessary on a long-term basis to maintain binocular alignment for viewing near targets. An excellent initial response is associated with a lower likelihood that the bifocals can be withdrawn later without recurrence of the esotropia.
      • Ludwig IH
      • Parks MM
      • Getson PR
      Long-term results of bifocal therapy for accommodative esotropia.
      Further, sensory outcomes may not be improved in patients treated with bifocals for high AC/A esotropia.
      • Whitman MC
      • MacNeill K
      • Hunter DG
      Bifocals fail to improve stereopsis outcomes in high AC/A accommodative esotropia.
      Bifocals should be an executive or a flat-top (D-segment) type, with the top of the bifocal bisecting the pupil in primary gaze in preschool children and a few millimeters lower in older children. The minimum strength of the bifocal can sometimes be estimated by office testing in trial frames or can be empirically prescribed +2.50 to +3.00 D and later reduced as tolerated. Reductions can be made later as part of a routine eyeglass change. Progressive bifocals offer cosmetic advantages and are often preferred by older children who have adapted well to standard bifocals. The transition zone should be placed several millimeters higher than the standard adult fitting.
      • Smith JB
      Progressive-addition lenses in the treatment of accommodative esotropia.
      Disadvantages of bifocals include appearance and potential rejection by the child. Some clinicians avoid bifocals because they believe that alignment at distance is sufficient to protect binocular vision.
      • Whitman MC
      • MacNeill K
      • Hunter DG
      Bifocals fail to improve stereopsis outcomes in high AC/A accommodative esotropia.
      • Gerling A
      • Arnoldi K
      Single-vision lenses: a comparison of management of high AC/A esotropia and refractive esotropia.
      In some cases, strabismus surgery is appropriate in older children to reduce dependence on bifocals or to allow for transition to contact lenses. Surgical correction can reduce the AC/A ratio
      • Bateman JB
      • Parks MM
      Clinical and computer-assisted analyses of preoperative and postoperative accommodative convergence and accommodation relationships.
      • Arnoldi KA
      • Tychsen L
      Surgery for esotropia with a high accommodative convergence/accommodation ratio: effects on accommodative vergence and binocularity.
      and eliminate the need for bifocal wear without producing consecutive exotropia at distance.
      • Lueder GT
      • Norman AA
      Strabismus surgery for elimination of bifocals in accommodative esotropia.
      • Millicent M
      • Peterseim W
      • Buckley EG
      Medial rectus fadenoperation for esotropia only at near fixation.
      • Zak TA
      Results of large single medial rectus recession.

       Prism Therapy

      Prisms are rarely useful in infantile esotropia, in part because the angle of deviation is usually too large to correct with prisms alone. In some patients with acquired esotropia who have diplopia, prism therapy may be beneficial in promoting binocular vision. Membrane prisms (Fresnel) may also be used for preoperative prismatic adaptation to establish the full angle on which to base extraocular muscle surgery.
      • Prism Adaptation Study Research Group
      Efficacy of prism adaptation in the surgical management of acquired esotropia.
      The Prism Adaptation Study investigated the role of preoperative membrane prisms to determine the maximum angle of the strabismus for surgical planning and to estimate fusional potential. Rates of surgical success, defined as a horizontal deviation of 8 prism diopters or less (measured with the simultaneous prism and cover test at distance fixation), were highest (90%) among those participants who responded to prisms (i.e., showed evidence of sensory fusion) and underwent extraocular muscle surgery for the adapted (larger) angle of esotropia.
      • Repka MX
      • Connett JE
      • Scott WE
      The one-year surgical outcome after prism adaptation for the management of acquired esotropia.
      • Prism Adaptation Study Research Group
      Efficacy of prism adaptation in the surgical management of acquired esotropia.
      However, because prism-adapted patients received greater amounts of surgery on average, it is possible that increasing surgical dosage for patients with potential for fusion without prism adaptation would have produced similar results. Membrane prisms cause visual symptoms that some children find objectionable (blurred vision with poor compliance with eyeglasses), In addition, using membrane prisms requires re-evaluation (additional office visits) and may be unacceptable to children not otherwise wearing eyeglasses. For these reasons, prism adaptation is used selectively.

       Amblyopia Treatment

      Amblyopia treatment is typically initiated before surgical treatment of strabismus. The esotropia may increase or decrease with the treatment of amblyopia
      • Archer SM
      • Helveston EM
      • Miller KK
      • Ellis FD
      Stereopsis in normal infants and infants with congenital esotropia.
      (see Amblyopia PPP
      • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
      Preferred Practice Pattern®. Amblyopia.
      ). Surgical treatment of esotropia in the presence of moderate to severe amblyopia has a lower success rate than in the presence of mild or no amblyopia.
      • Weakley Jr., DR
      • Holland DR
      Effect of ongoing treatment of amblyopia on surgical outcome in esotropia.

       Extraocular Muscle Surgery

      Children with esotropia should undergo surgical correction if eyeglasses and amblyopia management are insufficient to align the eyes,
      • Bateman JB
      • Parks MM
      • Wheeler N
      Discriminant analysis of acquired esotropia surgery. Predictor variables for short- and long-term outcomes.
      and strabismus surgery should be performed only when more conservative methods have failed or are unlikely to be of benefit. Surgery is rarely justified when the primary objective is to eliminate eyeglasses. Except for acquired symptomatic deviations in older children, small-angle deviations of less than 12 prism diopters at distance or near are not usually considered for surgery.
      Although some binocular vision and stereopsis can be restored after surgical alignment in many patients with infantile esotropia,
      • Rogers GL
      • Bremer DL
      • Leguire LE
      • Fellows RR
      Clinical assessment of visual function in the young child: a prospective study of binocular vision.
      • Archer SM
      • Helveston EM
      • Miller KK
      • Ellis FD
      Stereopsis in normal infants and infants with congenital esotropia.
      achievement of high-grade stereopsis is rare.
      • Ing MR
      Early surgical alignment for congenital esotropia.
      • Bateman JB
      • Parks MM
      • Wheeler N
      Discriminant analysis of congenital esotropia surgery. Predictor variables for short- and long-term outcomes.
      • von Noorden GK
      A reassessment of infantile esotropia. XLIV Edward Jackson memorial lecture.
      In contrast, the quality of stereopsis appears to be improved by prompt surgical realignment in patients with decompensated accommodative esotropia.
      • Bateman JB
      • Parks MM
      • Wheeler N
      Discriminant analysis of congenital esotropia surgery. Predictor variables for short- and long-term outcomes.
      • Bateman JB
      • Parks MM
      • Wheeler N
      Discriminant analysis of acquired esotropia surgery. Predictor variables for short- and long-term outcomes.
      • Helveston EM
      • Ellis FD
      • Schott J
      • et al.
      Surgical treatment of congenital esotropia.
      Most patients with infantile esotropia receive surgical intervention during childhood, but it is unknown whether early treatment results in improved long-term motor alignment. However, achieving binocular alignment early in life (before age 2 years) to within 10 prism diopters of orthotropia increases the likelihood of achieving binocularity
      • Ing MR
      Early surgical alignment for congenital esotropia.
      • Bateman JB
      • Parks MM
      • Wheeler N
      Discriminant analysis of congenital esotropia surgery. Predictor variables for short- and long-term outcomes.
      • Birch EE
      • Stager DR
      • Everett ME
      Random dot stereoacuity following surgical correction of infantile esotropia.
      • Ing MR
      Outcome study of surgical alignment before six months of age for congenital esotropia.
      • Birch EE
      • Stager Sr., DR
      Long-term motor and sensory outcomes after early surgery for infantile esotropia.
      and may decrease the risk for the development of dissociated vertical deviation.
      • Shin KH
      • Paik HJ
      Factors influencing the development and severity of dissociated vertical deviation in patients with infantile esotropia.
      Whether or not there is surgical realignment of infantile esotropia, many affected children subsequently develop other motility problems, such as latent nystagmus, dissociated strabismus, and inferior oblique muscle overaction.
      • Helveston EM
      • Neely DF
      • Stidham DB
      • et al.
      Results of early alignment of congenital esotropia.
      • Wilson ME
      • Parks MM
      Primary inferior oblique overaction in congenital esotropia, accommodative esotropia, and intermittent exotropia.
      The presence of amblyopia
      • Weakley Jr., DR
      • Holland DR
      Effect of ongoing treatment of amblyopia on surgical outcome in esotropia.
      or nystagmus
      • Sprunger DT
      • Wasserman BN
      • Stidham DB
      The relationship between nystagmus and surgical outcome in congenital esotropia.
      is associated with an increased rate of requiring reoperation. In one study, infantile esotropia reoccurred postoperatively on an accommodative basis in 50% of patients and correlated with the magnitude of the hyperopia.
      • Birch EE
      • Fawcett S
      • Stager DR
      Why does early surgical alignment improve stereoacuity outcomes in infantile esotropia?.
      Extraocular muscle surgery is usually performed for the maximum distance angle of deviation when the individual is wearing full hyperopic correction; however, some surgeons use the maximum near deviation. For patients with a distance-near disparity (high AC/A ratio; i.e., 10 prism diopters or greater
      • Bateman JB
      • Parks MM
      Clinical and computer-assisted analyses of preoperative and postoperative accommodative convergence and accommodation relationships.
      ), bilateral medial rectus recession usually reduces the AC/A ratio,
      • Archer SM
      The effect of medial versus lateral rectus muscle surgery on distance-near incomitance.
      decreasing the need for bifocals by reducing the esodeviation at near fixation.
      • Arnoldi KA
      • Tychsen L
      Surgery for esotropia with a high accommodative convergence/accommodation ratio: effects on accommodative vergence and binocularity.
      The higher the preoperative AC/A ratio, the greater the chance for postoperative normalization (i.e., restoring a more normal pattern of accommodative vergence)
      • Bateman JB
      • Parks MM
      Clinical and computer-assisted analyses of preoperative and postoperative accommodative convergence and accommodation relationships.
      and improving binocularity.
      • Arnoldi KA
      • Tychsen L
      Surgery for esotropia with a high accommodative convergence/accommodation ratio: effects on accommodative vergence and binocularity.
      Prism adaptation for the near angle,
      • Kutschke PJ
      • Scott WE
      • Stewart SA
      Prism adaptation for esotropia with a distance-near disparity.
      augmentation of the recession over amounts done with a normal AC/A ratio,
      • Kushner BJ
      • Preslan MW
      • Morton GV
      Treatment of partly accommodative esotropia with a high accommodative convergence-accommodation ratio.
      or posterior fixation sutures
      • Millicent M
      • Peterseim W
      • Buckley EG
      Medial rectus fadenoperation for esotropia only at near fixation.
      increase the likelihood of a satisfactory alignment and eventual weaning from bifocals.
      The amount of surgery and the choice of surgical technique may vary (e.g., methods of suture placement in the muscle and sclera, or measurement of recession or resection). Although two-muscle surgery is most frequently performed, three- or four-horizontal-muscle surgery may be required for large-angle deviations.
      • Lee DA
      • Dyer JA
      Bilateral medial rectus muscle recession and lateral rectus muscle resection in the treatment of congenital esotropia.
      Some clinicians believe that two-muscle surgery is the better initial choice even for large-angle deviations, regardless of magnitude, to reduce the risk of consecutive exotropia.
      • Vroman DT
      • Hutchinson AK
      • Saunders RA
      • Wilson ME
      Two-muscle surgery for congenital esotropia: rate of reoperation in patients with small versus large angles of deviation.
      Adjustable sutures have been advocated as an adjunct to strabismus surgery to improve motor outcomes, especially for patients with restrictive disease or for those requiring reoperation. Its utility in children remains unproven.
      • Sundaram V
      • Haridas A
      Adjustable versus non-adjustable sutures for strabismus.
      Moreover, the adjustment is challenging to do in younger children who may not cooperate well.
      Results may be similar with different surgical procedures; one method may be chosen over another on the basis of preoperative diagnosis, angle of deviation at distance and near, technical ease, anatomical exposure, the need for an assistant, presence of scar tissue, and other factors such as physician preference and experience. Bilateral medial rectus-muscle recessions are commonly performed as the initial surgical procedure. Most surgeons prefer unilateral or ipsilateral surgery (single-muscle recession or recession/resection) for patients with irreversible amblyopia or substantially reduced vision in one eye. Operating on both eyes may be preferable in specific clinical circumstances, such as V-pattern esotropia with inferior oblique-muscle overaction or null-point nystagmus with compensatory face turn. Detailed discussion of the surgical indications and management of complex deviations is beyond the scope of this publication.

       Botulinum toxin injection

      Chemodenervation by injection of botulinum toxin into one or more extraocular muscles induces a temporary weakness by pharmacologically blockading the neuromuscular junction. Although the mechanism of long-term ocular realignment in children is unknown, it likely results from contracture of the direct antagonist combined with motor and sensory adaptations that allow restoration of some degree of binocularity. As with conventional extraocular muscle surgery, favorable prognostic indicators include good vision in each eye, absence of restricted eye movement, a small to moderate angle of esotropia, and the potential for binocular vision. Such treatment may be an alternative to conventional extraocular muscle surgery in selected patients,
      • Tejedor J
      • Rodriguez JM
      Retreatment of children after surgery for acquired esotropia: reoperation versus botulinum injection.
      but its value in managing infantile esotropia has not been definitively established.
      • Rowe FJ
      • Noonan CP
      Botulinum toxin for the treatment of strabismus.
      • McNeer KW
      • Tucker MG
      • Spencer RF
      Management of essential infantile esotropia with botulinum toxin A: review and recommendations.
      • Ing MR
      Botulinum toxin treatment of infantile esotropia in children.
      • McNeer KW
      • Tucker MG
      • Spencer RF
      Botulinum toxin therapy for essential infantile esotropia in children.
      • Kushner BJ
      Botulinum toxin management of essential infantile esotropia in children.
      • McNeer KW
      • Tucker MG
      • Spencer RF
      Botulinum toxin management of essential infantile esotropia in children.
      Disadvantages include the frequent need for repeat injection(s), especially with larger preoperative angles; iatrogenic ptosis, which may increase the risk for amblyopia; globe perforation; tonic pupil;
      • Palmer EA
      Drug toxicity in pediatric ophthalmology.
      and the need for general anesthesia. Since treatment is administered by injection, treatment complications relate principally to trauma from the needle or toxin leakage. Careful injection technique and preinjection counseling are essential. Importantly, delayed binocular realignment may be disadvantageous in an infant with a rapidly developing visual system.

       Other Pharmacologic Agents

      Cholinesterase inhibitors, such as echothiophate iodide, reduce accommodative effort and convergence by stimulating ciliary muscle contraction (pupillary size is also reduced). Although sometimes effective, long-term use of this is less desirable than using corrective lenses because of a risk of adverse systemic side effects such as diarrhea, asthma, and/or increased salivation and perspiration as well as increased risk associated with the administration of certain agents (e.g., succinylcholine chloride) used in general anesthesia.
      • Palmer EA
      Drug toxicity in pediatric ophthalmology.
      Potential ocular side effects include cataract, retinal detachment, and iris cysts, which may encroach on the visual axis.
      • Axelsson U
      Glaucoma, miotic therapy and cataract. I. The frequency of anterior subcapsular vacuoles in glaucoma eyes treated with echothiophate (Phospholine Iodide), pilocarpine or pilocarpine-eserine, and in nonglaucomatous untreated eyes with common senile cataract.
      • Kraushar MF
      • Steinberg JA
      Miotics and retinal detachment: upgrading the community standard.
      • Axelsson U
      • Nyman KG
      Side effects from use of long-acting cholinesterase inhibitors in young persons.
      Some ophthalmologists prescribe phenylephrine 2.5% eyedrops twice daily to be used concurrently with the cholinesterase inhibitor to reduce the risk of iris cyst formation. Echothiophate iodide may be difficult to obtain in the United States.
      Training in diplopia recognition (antisuppression training) and strengthening vergence amplitudes is generally ineffective in the treatment of esotropic patients and may occasionally produce permanent diplopia, especially in patients with monofixation syndrome.
      • Helveston EM
      Visual training: current status in ophthalmology.

       Perioperative Care

       Preoperative Management

      Once a decision has been made to proceed with strabismus repair, preoperative counseling with the patient or parents/caregivers should include a realistic discussion of the goals of surgery, potential benefits of surgery, and risks of surgery and anesthesia. If the patient has any significant systemic risk factors for surgery, a pre-anesthesia evaluation with the primary care physician or specialty physician or anesthesiology service is essential. Sometimes a tour of the surgical facility by the patient and family can relieve presurgical anxiety, especially for young children.

       Postoperative Management

      Management of pain and nausea, diet, and antibiotic prophylaxis are addressed in the immediate postoperative period. Pain management in children is usually limited to nonnarcotic analgesics. Narcotics are avoided in children, if possible, because of the risk of nausea, vomiting, and dehydration. Anti-emetics, such as ondansetron, may be used postoperatively to control nausea. Diet is advanced slowly in the first 24 hours following surgery. Many surgeons use a combination antibiotic-corticosteroid preparation for the first week after surgery, although its effectiveness in reducing the risk of postoperative infection is not proven. Parents need to be advised of the risks and signs of postoperative complications, especially orbital cellulitis and slipped or lost muscle.

       Follow-up Evaluation

      Even when initial treatment results in good binocular alignment, follow-up is essential, because the child remains at high risk for developing amblyopia, losing binocular vision, and having a recurrence of strabismus. Children who are well aligned and do not have amblyopia may be followed every 4 to 6 months. As the child matures, the frequency of follow-up visits can be reduced.
      • Pediatric Eye Disease Investigator Group
      Randomized trial of treatment of amblyopia in children aged 7 to 17 years.
      New or changing findings may indicate the need for more frequent follow-up examinations.
      In children with esotropia, hyperopia should be assessed at least annually and more frequently if visual acuity decreases or the esotropia increases. Detection of uncorrected hyperopia is essential in the child with a recurrence of esotropia after successful initial treatment. Cyclopentolate 1% is effective in most patients for obtaining cycloplegia for refraction. In some patients, more hyperopia may be documented after regular eyeglass wear. If the esotropia appears to be accommodative in etiology but is not controlled with the current eyeglasses, repeat cycloplegic refraction should be performed before concluding that the esotropia has a nonaccommodative component. Atropine 1% may be used to establish adequate cycloplegia when shorter-acting drugs are inadequate.
      • Rosenbaum AL
      • Bateman JB
      • Bremer DL
      • Liu PY
      Cycloplegic refraction in esotropic children. Cyclopentolate versus atropine.
      Recurrence of esotropia or consecutive exotropia that is not responsive to eyeglasses, patching, or medical treatment may indicate the need for repeat strabismus surgery if the magnitude of the strabismus is sufficient.

       PROVIDER AND SETTING

      Certain eye care services and procedures, including elements of the eye examination, may be delegated to appropriately trained and supervised auxiliary health care personnel under the ophthalmologist's supervision.
      • American Academy of Ophthalmology
      Code of Ethics. B. Rules of ethics, #7. Delegation of services.
      For cases in which the diagnosis or management is difficult, consultation with or referral to an ophthalmologist who specializes in the diagnosis and treatment of pediatric patients may be desirable. The operating ophthalmologist has the ultimate responsibility for the preoperative assessment and postoperative care of the patient, beginning with the determination of the need for surgery and ending with completion of the postoperative care contingent on medical stability of the patient. Postoperative care responsibilities may be ethically delegated to another nonoperating healthcare practitioner, whether as part of a co-management arrangement or as a transfer of care, under appropriate circumstances.
      Comprehensive Guidelines for the Co-Management of Ophthalmic Postoperative Care.
      • American Academy of Ophthalmology
      Policy Statement. Preoperative Assessment: Responsibilities of the Ophthalmologist.
      • American Academy of Ophthalmology
      Policy Statement. An Ophthalmologist's Duties Concerning Postoperative Care.

       COUNSELING AND REFERRAL

      Childhood esotropia is a long-term problem that requires commitment from the patient and/or family/caregiver and the ophthalmologist to achieve the best possible outcome.
      The ophthalmologist should discuss the findings of the evaluation with the patient, when appropriate, as well as with the parent/caregiver. The ophthalmologist should explain the disorder and include the family in a collaborative approach to therapy. Parents/caregivers of pediatric patients who understand the diagnosis and rationale for treatment are more likely to adhere to treatment recommendations.
      • Newsham D
      A randomised controlled trial of written information: the effect on parental non-concordance with occlusion therapy.
      • Norman P
      • Searle A
      • Harrad R
      • Vedhara K
      Predicting adherence to eye patching in children with amblyopia: an application of protection motivation theory.

      Section II. Exotropia

       INTRODUCTION

       DISEASE DEFINITION

      Exotropia is a divergent misalignment of the visual axes. The scope of this section is limited to the following forms of exotropia:
      • Infantile exotropia
      • Intermittent exotropia
      • Convergence insufficiency
      • Other

       Infantile Exotropia

      Infantile exotropia appears before 6 months of age and is a constant exotropia that has many characteristics similar to infantile esotropia, including limited binocular potential, oblique dysfunction, latent nystagmus, and dissociated vertical deviation. Neonates frequently have intermittent exotropia during the first 3 to 4 months of life; however, it rarely persists.
      • Nixon RB
      • Helveston EM
      • Miller K
      • et al.
      Incidence of strabismus in neonates.
      Children with neurodevelopmental delay may have constant exotropia from infancy. Children with infantile exotropia are at risk for amblyopia.

       Intermittent Exotropia

      Childhood-onset exotropia is typically intermittent and usually appears before 3 years of age, but it may be first detected later in childhood. The deviation often becomes manifest with fatigue, visual inattention, or illness when fusional compensatory mechanisms are compromised. The patient may close or cover one eye in bright light. Generally, the image from the deviated eye is suppressed and the patient does not report diplopia. Mild amblyopia occasionally occurs, but severe amblyopia is uncommon in intermittent exotropia.

       Convergence Insufficiency

      Older children and teenagers with convergence insufficiency typically have intermittent exotropia at near fixation, reduced convergence fusional amplitudes, and a remote near point of convergence. They often report asthenopic symptoms with near work.

       Other

      Sensory exotropia is associated with unilateral or bilateral vision loss on a structural basis. Consecutive exotropia occurs in some children after surgery for esotropia. Sensory and consecutive exotropias are not within the scope of this document.
      Other conditions that are associated with exotropia include Duane syndrome, congenital fibrosis syndrome, craniofacial abnormalities, and ocular myasthenia gravis. Dissociated horizontal deviation is a divergent misalignment of the eyes and typically occurs in patients with a history of infantile esotropia.
      Pseudoexotropia is caused by positive angle kappa, which is a disparity between the visual and anatomic axes of the eyes (e.g., retinopathy of prematurity with macula ectopia.

       PATIENT POPULATION

      Patients with childhood onset of exotropia.

       CLINICAL OBJECTIVES

      • Identify children at risk for exotropia
      • Detect exotropia
      • Detect and treat amblyopia that may be associated with exotropia (see Amblyopia PPP
        • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
        Preferred Practice Pattern®. Amblyopia.
        )
      • Educate the patient, as appropriate, about the diagnosis, treatment options, and care plan
      • Inform the patient's other health providers of the diagnosis and treatment plan
      • When indicated, treat the exotropia (align the visual axes to promote and maintain binocular vision [fusion, stereopsis]), prevent or facilitate treatment of amblyopia, and restore normal appearance
      • Maximize quality of life by optimizing binocular alignment and visual acuity
      • Monitor vision and binocular alignment and modify therapy as appropriate

       BACKGROUND

       PREVALENCE AND RISK FACTORS

      Exotropia occurs in approximately 1% of the population; intermittent exotropia is the most frequently reported type.
      Multi-ethnic Pediatric Eye Disease Study Group
      Prevalence of amblyopia and strabismus in African American and Hispanic children ages 6 to 72 months: the Multi-ethnic Pediatric Eye Disease Study.
      • Friedman DS
      • Repka MX
      • Katz J
      • et al.
      Prevalence of amblyopia and strabismus in white and African American children aged 6 through 71 months: the Baltimore Pediatric Eye Disease Study.
      • Mohney BG
      • Huffaker RK
      Common forms of childhood exotropia.
      • Govindan M
      • Mohney BG
      • Diehl NN
      • Burke JP
      Incidence and types of childhood exotropia: a population-based study.
      A large study of mono- and dizygotic twins found evidence of heritability for esodeviation, but no such association was found for exodeviation.
      • Sanfilippo PG
      • Hammond CJ
      • Staffieri SE
      • et al.
      Heritability of strabismus: genetic influence is specific to eso-deviation and independent of refractive error.
      Exotropia has been associated with prematurity, perinatal morbidity, genetic disorders, detrimental prenatal environmental influences, (e.g., maternal substance abuse and smoking), family history of strabismus, female sex, astigmatism, myopia, and anisometropia.
      Multi-ethnic Pediatric Eye Disease Study Group
      Prevalence of amblyopia and strabismus in African American and Hispanic children ages 6 to 72 months: the Multi-ethnic Pediatric Eye Disease Study.
      • Friedman DS
      • Repka MX
      • Katz J
      • et al.
      Prevalence of amblyopia and strabismus in white and African American children aged 6 through 71 months: the Baltimore Pediatric Eye Disease Study.
      Joint Writing Committee for the Multi-Ethnic Pediatric Eye Disease Study and the Baltimore Pediatric Eye Disease Study Groups
      Risk factors associated with childhood strabismus: the Multi-Ethnic Pediatric Eye Disease and Baltimore Pediatric Eye Disease Studies.
      • Chew E
      • Remaley NA
      • Tamboli A
      • et al.
      Risk factors for esotropia and exotropia.
      One small retrospective population-based cohort study in the United States found that intermittent exotropia was twice as frequent in girls than in boys.
      • Nusz KJ
      • Mohney BG
      • Diehl NN
      Female predominance in intermittent exotropia.
      Clinic-based studies of children with infantile-onset exotropia found that half had associated ocular or systemic anomalies.
      • Coats DK
      • Demmler GJ
      • Paysse EA
      • et al.
      Ophthalmologic findings in children with congenital cytomegalovirus infection.
      • Hunter DG
      • Ellis FJ
      Prevalence of systemic and ocular disease in infantile exotropia: comparison with infantile esotropia.
      In the long-term, reduction or prevention of factors, such as prematurity and maternal smoking during pregnancy, as well as diagnosis and treatment of myopia and myopic anisometropia may reduce the incidence of exotropia.

       NATURAL HISTORY

      Although classifications derived from presumed etiologic bases have been used, exotropia is usually described clinically on the basis of frequency of the deviation, laterality, magnitude at distance and at near vision, and symptoms. Some studies suggest that many patients who decline surgical correction appear to remain stable or spontaneously improve with observation alone,
      • Chia A
      • Seenyen L
      • Long QB
      A retrospective review of 287 consecutive children in Singapore presenting with intermittent exotropia.
      • Romanchuk KG
      • Dotchin SA
      • Zurevinsky J
      The natural history of surgically untreated intermittent exotropia-looking into the distant future.
      but others report deterioration during long-term follow-up.
      • Nusz KJ
      • Mohney BG
      • Diehl NN
      The course of intermittent exotropia in a population-based cohort.
      Von Noorden followed 51 patients ages 5 to 10 years with intermittent exotropia for an average of 3.5 years and found that an increase in angle size, decrease in fusional control, and/or development of suppression occurred in 75%.
      • von Noorden GK
      • Campos EC
      Exodeviations. Binocular Vision and Ocular Motility: Theory and Management of Strabismus.
      However, a more recent study of 109 patients followed for an average of 9 years found that there was no trend for worsening or improvement of the size or control of exodeviation angle.
      • Romanchuk KG
      • Dotchin SA
      • Zurevinsky J
      The natural history of surgically untreated intermittent exotropia-looking into the distant future.
      In parallel randomized clinical trials, 4.6% of children 12 to 35 months and 6.1% between age 3 years up to 11 years showed deterioration of intermittent exotropia when observed for 6 months.
      • Pediatric Eye Disease Investigator Group
      • Cotter SA
      • Mohney BG
      • Chandler DL
      • et al.
      A randomized trial comparing part-time patching with observation for children 3 to 10 years of age with intermittent exotropia.
      • Pediatric Eye Disease Investigator Group
      • Mohney BG
      • Cotter SA
      • Chandler DL
      • et al.
      A randomized trial comparing part-time patching with observation for intermittent exotropia in children 12 to 35 months of age.
      A small proportion of children with intermittent exotropia eventually develop a constant deviation, which may cause binocular vision to deteriorate in some children.
      • Wu H
      • Sun J
      • Xia X
      • et al.
      Binocular status after surgery for constant and intermittent exotropia.
      The causes of exotropia are poorly understood. Proposed etiologies for exotropia include excess tonic divergence and mechanical or orbital factors.
      • von Noorden GK
      • Campos EC
      Exodeviations. Binocular Vision and Ocular Motility: Theory and Management of Strabismus.
      Severe unilateral or bilateral vision loss may cause exotropia. Typically, unilateral poor vision in early childhood is associated more with esotropia than with exotropia.

       RATIONALE FOR TREATMENT

      The potential benefits of treatment for exotropia include promoting binocular vision and normal visual function in each eye. Normal binocular alignment promotes a positive self-image.
      • Sabri K
      • Knapp CM
      • Thompson JR
      • Gottlob I
      The VF-14 and psychological impact of amblyopia and strabismus.
      The appearance of misaligned eyes impairs self-image and social interactions and reduces employment opportunities.
      • Satterfield D
      • Keltner JL
      • Morrison TL
      Psychosocial aspects of strabismus study.
      • Burke JP
      • Leach CM
      • Davis H
      Psychosocial implications of strabismus surgery in adults.
      • Coats DK
      • Paysse EA
      • Towler AJ
      • Dipboye RL
      Impact of large angle horizontal strabismus on ability to obtain employment.
      • Johns HA
      • Manny RE
      • Fern KD
      • Hu YS
      The effect of strabismus on a young child's selection of a playmate.
      • Uretmen O
      • Egrilmez S
      • Kose S
      • et al.
      Negative social bias against children with strabismus.
      • Mojon-Azzi SM
      • Kunz A
      • Mojon DS
      Strabismus and discrimination in children: are children with strabismus invited to fewer birthday parties?.
      • Paysse EA
      • Steele EA
      • McCreery KM
      • et al.
      Age of the emergence of negative attitudes toward strabismus.
      In one study, children aged 5 years and older expressed a negative feeling about dolls that had been altered to be esotropic or exotropic.
      • Paysse EA
      • Steele EA
      • McCreery KM
      • et al.
      Age of the emergence of negative attitudes toward strabismus.
      In another study, elementary school teachers rated personal characteristics of children with esotropia and exotropia more negatively than orthotropic children.
      • Uretmen O
      • Egrilmez S
      • Kose S
      • et al.
      Negative social bias against children with strabismus.
      In a sample of children enrolled in the Multi-ethnic Pediatric Eye Disease Study, strabismus was associated with a decreased general health-related quality of life in preschool children, based on the parents' proxy reporting.
      • Wen G
      • McKean-Cowdin R
      • Varma R
      • et al.
      General health-related quality of life in preschool children with strabismus or amblyopia.
      After strabismus surgery, adults have reported improved confidence, self-esteem, and interpersonal interactions.
      • Burke JP
      • Leach CM
      • Davis H
      Psychosocial implications of strabismus surgery in adults.
      There is evidence that the severity of exotropia negatively affects a child and/or his or her parent's quality of life,
      • Lim SB
      • Wong WL
      • Ho RC
      • Wong IB
      Childhood intermittent exotropia from a different angle: does severity affect quality of life?.
      • Yamada T
      • Hatt SR
      • Leske DA
      • Holmes JM
      Health-related quality of life in parents of children with intermittent exotropia.
      whereas surgical intervention may have a positive impact on a child's quality of life.
      • Wang X
      • Gao X
      • Xiao M
      • et al.
      Effectiveness of strabismus surgery on the health-related quality of life assessment of children with intermittent exotropia and their parents: a randomized clinical trial.
      • Clarke M
      • Hogan V
      • Buck D
      • et al.
      An external pilot study to test the feasibility of a randomised controlled trial comparing eye muscle surgery against active monitoring for childhood intermittent exotropia [X(T)].
      • Kushner BJ
      The distance angle to target in surgery for intermittent exotropia.
      In a pilot randomized trial comparing surgery with active monitoring, the children randomized to surgery had significantly better quality of life scores for psychosocial and visual function subscales.
      • Clarke M
      • Hogan V
      • Buck D
      • et al.
      An external pilot study to test the feasibility of a randomised controlled trial comparing eye muscle surgery against active monitoring for childhood intermittent exotropia [X(T)].

       CARE PROCESS

       PATIENT OUTCOME CRITERIA

      • Optimal binocular motor alignment
      • Optimal binocular sensory status (fusion and stereopsis)
      • Optimal visual acuity in each eye

       DIAGNOSIS

      The purpose of the initial comprehensive strabismus evaluation is to confirm the diagnosis, establish baseline status, inform the patient and/or family/caregiver, and determine therapy. Secondary causes for the strabismus should be considered, including restrictive and paralytic deviations caused by head trauma or increased intracranial pressure.
      The examination of a patient who has childhood-onset strabismus includes all elements of the comprehensive ophthalmic examination in addition to sensory, motor, refractive, and accommodative testing.
      • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
      Preferred Practice Pattern®. Pediatric Eye Evaluations.
      • Feder RS
      • Olsen TW
      • Prum Jr., BE
      • et al.
      Comprehensive Adult Medical Eye Evaluation Preferred Practice Pattern® Guidelines.
      The esotropia section of this document contains details of the comprehensive strabismus evaluation, and examination elements specific to exotropia are discussed in this section.

       History

      The medical history should include an estimate of the proportion of waking time that the eyes appear to be misaligned, whether there is an ability to control the deviation, when the deviation occurs (e.g., when tired, ill, daydreaming, or viewing distant objects), and whether the frequency is changing. In addition, it is helpful to ascertain whether one or both eyes are observed to deviate.

       Examination

      Sensory tests (e.g., stereopsis) should be done before visual acuity and alignment measurements, which may dissociate the eyes by monocular occlusion and cause reduced stereoacuity measurement or interfere with assessment of control of the exodeviation.
      The examination includes an assessment of the fusional control of the exodeviation at both distance and near fixation. The deviation is recorded as constant exotropia (XT), intermittent exotropia (X(T)), or exophoria (X). Fusional control can vary substantially from visit to visit or even within the same visit. Various scales have been developed to characterize control of exodeviations.
      • Haggerty H
      • Richardson S
      • Hrisos S
      • et al.
      The Newcastle Control Score: a new method of grading the severity of intermittent distance exotropia.
      • Mohney BG
      • Holmes JM
      An office-based scale for assessing control in intermittent exotropia.
      • Hatt SR
      • Leske DA
      • Liebermann L
      • Holmes JM
      Quantifying variability in the measurement of control in intermittent exotropia.
      Indicators of progression include worsening control, reduction in stereoacuity, and/or development of suppression. Some practitioners augment near stereoacuity tests with an assessment of distance stereoacuity, which may detect reduced distance fusional control.
      • Wang J
      • Hatt SR
      • O'Connor AR
      • et al.
      Final version of the Distance Randot Stereotest: normative data, reliability, and validity.
      • Holmes JM
      • Birch EE
      • Leske DA
      • et al.
      New tests of distance stereoacuity and their role in evaluating intermittent exotropia.
      Binocular alignment can be evaluated using a variety of clinical methods. When possible, a target that controls the patient's accommodation should be used for both distant and near fixation when measuring alignment. The method of measuring the angle of exotropia and the presence or absence of refractive correction should be documented. If the patient is unable to participate in more sophisticated testing, the angle may be estimated using the corneal light-reflection test with or without prisms or by estimating the amount of eye movement required to refixate with alternate-cover testing without prism. The prism and alternate-cover test measures the total deviation and, as such, is used to quantify the amount of surgery, if required.
      • Choi RY
      • Kushner BJ
      The accuracy of experienced strabismologists using the Hirschberg and Krimsky tests.
      The simultaneous prism-and-cover test measures the manifest deviation and provides useful information for patients with fusional vergence, where the alignment under binocular viewing conditions is better than during alternate-cover testing.

       MANAGEMENT

      All forms of exotropia should be monitored and some require treatment. Young children with intermittent exotropia and good fusional control should be followed without surgery.
      • Buck D
      • Powell CJ
      • Rahi J
      • et al.
      The improving outcomes in intermittent exotropia study: outcomes at 2 years after diagnosis in an observational cohort.
      (moderate evidence, strong recommendation) Deviations that are present most or all of the time often require treatment. However, the optimal therapy for exotropia, the long-term benefit of early surgical correction, and the relative merits of bilateral versus unilateral surgery are not well established.
      • Hatt S
      • Gnanaraj L
      Interventions for intermittent exotropia.
      Amblyopia is uncommon in patients with intermittent exotropia, but, if present, should be treated.

       Choice of Therapy

      Current treatment practices are listed below. Some of these treatments are under evaluation in randomized trials.
      • Correction of refractive errors
      • Stimulating accommodative convergence (overcorrection of myopia or undercorrection of hyperopia)
      • Patching (antisuppression) therapy
      • Amblyopia treatment
      • Prism therapy
      • Convergence exercises for convergence insufficiency exotropia
      • Extraocular muscle surgery
      • Botulinum toxin injection
        • Rowe FJ
        • Noonan CP
        Botulinum toxin for the treatment of strabismus.

       Correction of Refractive Errors

      In the setting of an exodeviation, corrective lenses should be prescribed for any clinically significant refractive error that causes reduced vision in one or both eyes.
      • Buck D
      • Powell CJ
      • Rahi J
      • et al.
      The improving outcomes in intermittent exotropia study: outcomes at 2 years after diagnosis in an observational cohort.
      Improved retinal-image clarity often improves the control of the exotropia.
      • Iacobucci IL
      • Archer SM
      • Giles CL
      Children with exotropia responsive to spectacle correction of hyperopia.
      Such refractive errors include myopia, high hyperopia, astigmatism, and significant anisometropia. In one study, myopia was found in more than 90% of exotropic patients by 20 years of age.
      • Ekdawi NS
      • Nusz KJ
      • Diehl NN
      • Mohney BG
      The development of myopia among children with intermittent exotropia.
      Correcting even mild amounts of myopia may be beneficial. Correction of mild to moderate amounts of hyperopia is not generally recommended for patients with intermittent exotropia because reducing accommodative convergence can worsen the control or size of the exodeviation. If hyperopic correction is necessary, the amount prescribed is the least amount needed to promote good vision while still promoting accommodative convergence to control the exodeviation. Such correction may be the full cycloplegic refraction,
      • Iacobucci IL
      • Archer SM
      • Giles CL
      Children with exotropia responsive to spectacle correction of hyperopia.
      but it is often less than the full amount.

       Stimulating Accommodative Convergence

      If fusional control of intermittent exotropia is suboptimal despite providing image clarity with refractive correction, it may be improved in many cases by increasing myopic correction in myopes, reducing hyperopic correction in hyperopes, or prescribing myopic correction in ametropes. In one multicenter pilot study, patients randomized to overminus therapy had better control of intermittent exotropia after 8 weeks, but the durability of the effect is uncertain.
      • Pediatric Eye Disease Investigator Group
      • Chen AM
      • Holmes JM
      • Chandler DL
      • et al.
      A randomized trial evaluating short-term effectiveness of overminus lenses in children 3 to 6 years of age with intermittent exotropia.
      Some patients, in particular older patients and adults, may not tolerate this therapy because of visual discomfort or decreased visual acuity. Studies suggest that overcorrecting minus-lens therapy stimulates accommodation without increasing myopia.
      • Caltrider N
      • Jampolsky A
      Overcorrecting minus lens therapy for treatment of intermittent exotropia.
      • Kushner BJ
      Does overcorrecting minus lens therapy for intermittent exotropia cause myopia?.
      It is most useful in patients with low-grade myopia and in those already wearing eyeglasses.

       Patching Therapy

      In some cases, part-time patching (e.g., 2 to 6 hours daily) may improve fusional control
      • Freeman RS
      • Isenberg SJ
      The use of part-time occlusion for early onset unilateral exotropia.
      • Berg PH
      • Isenberg SJ
      Treatment of unilateral exotropia by part-time occlusion.
      and/or reduce the angle of strabismus, particularly in the 3-to-10-year age group. It may be done on the preferred eye, or in the absence of a fixation preference, prescribed to alternate between eyes.
      Part-time patching, either unilateral or alternating, has been utilized as a treatment for intermittent exotropia. Deterioration of exotropia is uncommon. Two randomized clinical trials have determined that with or without patching, deterioration is uncommon, and patching may slightly lower the probability of deterioration.
      • Mohney BG
      • Cotter SA
      • Chandler DL
      • et al.
      A randomized trial comparing part-time patching with observation for intermittent exotropia in children 12 to 35 months of age.
      • Cotter SA
      • Mohney BG
      • Chandler DL
      • et al.
      A randomized trial comparing part-time patching with observation for children 3 to 10 years of age with intermittent exotropia.

       Amblyopia Treatment

      In children with exotropia, treatment for amblyopia
      • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
      Preferred Practice Pattern®. Amblyopia.
      may improve fusional control, decrease the angle of the exodeviation, and/or improve the postoperative success rate in those requiring strabismus surgery. Because amblyopia is uncommon in intermittent exotropia,
      • Mohney BG
      • Huffaker RK
      Common forms of childhood exotropia.
      the presence of reduced visual acuity without an obvious etiology (e.g., anisometropia or ocular structural abnormality) should alert the ophthalmologist to consider additional diagnoses, such as a subtle optic nerve or retinal abnormalities.

       Prism Therapy

      Patients with intermittent exotropia do not typically have diplopia, so prisms are not generally prescribed. However, some patients with intermittent exotropia have the convergence insufficiency type. In these cases, base-out prism can be used during convergence exercises (see the following subsection). In cases of symptomatic convergence insufficiency exotropia that is refractory to exercises, base-in prism can be included in eyeglasses to improve comfort while reading, although one study found this treatment was no better than placebo in children.
      • Scheiman M
      • Cotter S
      • Rouse M
      • et al.
      Randomised clinical trial of the effectiveness of base-in prism reading glasses versus placebo reading glasses for symptomatic convergence insufficiency in children.

       Convergence Exercises for Convergence Insufficiency

      Orthoptic therapy may improve fusional control in children or adults with convergence insufficiency and with small- to moderate-angle exodeviation (i.e., 20 prism diopters or less), with the goal of strengthening fusional convergence amplitudes.
      • Pritchard C
      Intermittent exotropia: how do they “turn out”? Richard G. Scobee Memorial Lecture.
      • Scheiman M
      • Mitchell GL
      • Cotter S
      • et al.
      the Convergence Insufficiency Treatment Trial (CITT) Study Group
      A randomized clinical trial of treatments for convergence insufficiency in children.
      Children and adults with the convergence insufficiency type of exotropia (exotropia greater at near) and asthenopic symptoms with near viewing (typically reading) may be good candidates for orthoptic therapy. Near point of convergence exercises on an accommodative target are useful if the near point of convergence is distant. Convergence exercises with a base-out prism may be beneficial once the near point of convergence improves. Treatment is tapered as symptoms improve, and it may need to be resumed if symptoms recur. Other treatments include computer-based convergence exercises and in-office orthoptics.
      Convergence Insufficiency Treatment Trial Study Group
      Randomized clinical trial of treatments for symptomatic convergence insufficiency in children.
      • Wallace DK
      Treatment options for symptomatic convergence insufficiency.
      • Scheiman M
      • Gwiazda J
      • Li T
      Non-surgical interventions for convergence insufficiency.

       Extraocular Muscle Surgery

      Surgical intervention is considered if the deviation is constant, if it occurs so frequently or is so large as to be unacceptable to the child or parent/caregiver, or if symptoms are not relieved by corrective lenses and nonsurgical treatment. Observing the control and size of the deviation under daily-life conditions is essential when making the decision to perform extraocular muscle surgery. Other preoperative considerations include age, refractive error, and the AC/A ratio. A change in refractive correction may increase or decrease the measured deviation and influence surgical planning. Measurements of exotropia with best optical correction should be repeated using accommodative targets at near, distance, and if possible, at remote distance (e.g., while a patient looks down a hallway or out of a window). Thirty minutes of monocular occlusion (patch test) may help to elicit the full deviation.
      If the distance angle exceeds the near angle by at least 10 prism diopters, –2.00 D lenses are placed over the usual refractive correction. If there is a significant decrease in the distance angle, a high AC/A ratio is diagnosed. In these patients, a nonsurgical approach may be warranted because there is a risk of consecutive esotropia with diplopia or asthenopia at near fixation.
      • Kushner BJ
      Diagnosis and treatment of exotropia with a high accommodation convergence-accommodation ratio.
      The timing of surgery for exotropia depends on the child's neurodevelopmental status and the frequency of the deviation. For constant infantile-onset exotropia, early surgery is indicated to improve sensory outcomes, although normal binocular function is rarely achieved. When the deviation is intermittent, many ophthalmologists defer surgery in young children with fusion to avoid complications associated with postoperative esotropia. These complications include suppression, amblyopia, and loss of binocular vision, particularly stereoacuity. However, excellent stereoacuity can be found in many patients who have undergone early surgery.
      • Paik HJ
      • Yim HB
      Clinical effect of early surgery in infantile exotropia.
      • Saunders RA
      • Trivedi RH
      Sensory results after lateral rectus muscle recession for intermittent exotropia operated before two years of age.
      In one retrospective cross-sectional study, alignment before age 7 years, before 5 years of strabismus duration, or while the deviation was intermittent increased the likelihood and quality of stereopsis.
      • Abroms AD
      • Mohney BG
      • Rush DP
      • et al.
      Timely surgery in intermittent and constant exotropia for superior sensory outcome.
      However, many surgeons elect to wait until the deviation is very frequent or there are significant psychosocial implications.
      Surgery consists of bilateral-lateral rectus-muscle recessions or unilateral-lateral rectus-muscle recession and medial rectus-muscle strengthening. Some surgeons prefer bilateral surgery when the distance deviation exceeds the near deviation and unilateral surgery when the near deviation is greater than the distance deviation. When poor vision is present in one eye, unilateral surgery on that eye typically is preferred. Bilateral surgery is preferable when there is an A or V pattern with or without significant oblique overaction. Upshift of both lateral rectus muscles improves a V pattern and downshift improves an A pattern. In the setting of exotropia, small vertical deviations typically do not require vertical muscle surgery. A single lateral rectus-muscle recession may be done for a small deviation.
      Although most surgeons prefer symmetric surgery (e.g., bilateral-lateral rectus-muscle recession), with recession amounts based on the distance deviation, excellent results are also obtained from unilateral two-muscle surgery (lateral rectus-muscle recession and medial rectus resection).
      • Kushner BJ
      Selective surgery for intermittent exotropia based on distance/near differences.
      • Kushner BJ
      The distance angle to target in surgery for intermittent exotropia.
      In a recent clinical trial, 197 children between age 3 years up to 11 years with basic-type intermittent exotropia were randomized to bilateral-lateral rectus recession or unilateral recess-resect. The primary outcome measure was the proportion of subjects with “suboptimal surgical outcome,” defined as exotropia of 10 prism diopters or more at distance or near, constant esotropia 6 prism diopters or more at distance or near, or loss of two or more octaves stereoacuity. The cumulative probability of suboptimal surgical outcome occurring at any masked examination between 6 months and 3 years after surgery was not significantly different between the groups: 46% (43 of 101) in the bilateral-lateral rectus recession group compared with 37% (33 of 96) in the unilateral recess-resect group (treatment group difference = 9%; 95% CI = −6% to 23%). Surgeons elected to reoperate by 3 years in 9 (10%) participants in the bilateral-lateral rectus recession group and in 4 (5%) participants in the unilateral recess-resect group.
      • Donahue S
      • Chandler DL
      • Holmes JM
      • Pediatric Eye Disease Investigator Group (PEDIG)
      • et al.
      Randomized trial comparing bilateral lateral rectus recession versus unilateral recess-resect for basic-type intermittent exotropia.
      A smaller randomized trial (n=36) found that long-term outcome was better after recess-resect than after bilateral recession.
      • Kushner BJ
      Selective surgery for intermittent exotropia based on distance/near differences.
      Esotropia that occurs immediately following surgery often causes diplopia. Some studies have reported that this overcorrection is usually temporary and may increase the likelihood of satisfactory long-term binocular alignment,
      • Oh JY
      • Hwang JM
      Survival analysis of 365 patients with exotropia after surgery.
      • Ruttum MS
      Initial versus subsequent postoperative motor alignment in intermittent exotropia.
      but another study reported a variable and unpredictable outcome following early overcorrection.
      • Pineles SL
      • Deitz LW
      • Velez FG
      Postoperative outcomes of patients initially overcorrected for intermittent exotropia.
      The duration of follow-up likely influences motor outcomes.
      • Pineles SL
      • Deitz LW
      • Velez FG
      Postoperative outcomes of patients initially overcorrected for intermittent exotropia.
      • Choi J
      • Kim SJ
      • Yu YS
      Initial postoperative deviation as a predictor of long-term outcome after surgery for intermittent exotropia.
      When a consecutive esotropia persists for several weeks, placement of temporary press-on prisms that are slowly reduced in power can be helpful. When unsuccessful, additional surgery is often required for the consecutive esotropia. Although approximately 80% of patients have good alignment 6 months postoperatively after bilateral-lateral rectus-muscle recession,
      • Ing MR
      • Nishimura J
      • Okino L
      Outcome study of bilateral lateral rectus recession for intermittent exotropia in children.
      long-term results are less favorable and recurrence is common over time.
      • Oh JY
      • Hwang JM
      Survival analysis of 365 patients with exotropia after surgery.
      • Maruo T
      • Kubota N
      • Sakaue T
      • Usui C
      Intermittent exotropia surgery in children: long term outcome regarding changes in binocular alignment. A study of 666 cases.
      Outcomes may be improved with a combination of surgical and nonsurgical (orthoptic/occlusion) therapy during management of a child with exotropia.
      • Figueira EC
      • Hing S
      Intermittent exotropia: comparison of treatments.
      Use of an adjustable suture technique (in older children and adults) has not been shown to improve outcomes in uncomplicated intermittent exotropia.
      • Sundaram V
      • Haridas A
      Adjustable versus non-adjustable sutures for strabismus.
      • Mohan K
      • Ram J
      • Sharma A
      Comparison between adjustable and non-adjustable hang-back muscle recession for concomitant exotropia.

       Botulinum toxin injection

      Chemodenervation by injection of botulinum toxin into one or more extraocular muscles has been used as initial, secondary, and adjunctive treatment for exotropia. In a randomized study (n=30, 20 with exotropia) of adjustable suture muscle surgery or chemodenervation by injection of botulinum toxin for adults with horizontal, nonaccommodative ocular misalignment, botulinum toxin treatment was less successful (29% vs. 77%) than surgery.
      • Carruthers JD
      • Kennedy RA
      • Bagaric D
      Botulinum vs adjustable suture surgery in the treatment of horizontal misalignment in adult patients lacking fusion.
      There is insufficient evidence to make treatment recommendations for botulinum toxin treatment for exotropia.
      • Rowe FJ
      • Noonan CP
      Botulinum toxin for the treatment of strabismus.

       Perioperative Care

      Refer to Perioperative Care in Section I. Esotropia of this PPP.

       Follow-up Evaluation

      Children with exotropia require follow-up evaluations to monitor the magnitude and frequency of the deviation, visual acuity, and binocularity. Young children with constant or poorly controlled exotropia or with postoperative consecutive esotropia are at risk for developing amblyopia, and they should be followed more frequently. Postoperative consecutive esotropia may also precipitate loss of stereoacuity. Prescribing base-out prism in eyeglasses is occasionally useful to alleviate diplopia associated with postoperative esotropia. The frequency of follow-up evaluations is based on the age of the child, the ability to obtain an accurate visual acuity, and the control of the deviation. Children with good fusional control of intermittent exotropia and without amblyopia are typically examined every 6 to 12 months. By age 7 to 10 years, the frequency of ophthalmological examinations may be reduced.
      Follow-up evaluation includes frequency of any deviation, adherence to treatment plan (if any), ocular motility assessment, and update of refractive correction, if needed.

       PROVIDER AND SETTING

      Certain eye care services and procedures, including elements of the eye examination, may be delegated to appropriately trained and supervised auxiliary health care personnel under the ophthalmologist's supervision.
      • American Academy of Ophthalmology
      Code of Ethics. B. Rules of ethics, #7. Delegation of services.
      For cases in which the diagnosis or management is difficult, consultation with or referral to an ophthalmologist who specializes in the diagnosis and treatment of pediatric patients may be desirable. The operating ophthalmologist has the ultimate responsibility for the preoperative assessment and postoperative care of the patient, beginning with the determination of the need for surgery and ending with completion of the postoperative care contingent on medical stability of the patient. Postoperative care responsibilities may be ethically delegated to another nonoperating healthcare practitioner, whether as part of a co-management arrangement or as a transfer of care, under appropriate circumstances.
      Comprehensive Guidelines for the Co-Management of Ophthalmic Postoperative Care.
      • American Academy of Ophthalmology
      Policy Statement. Preoperative Assessment: Responsibilities of the Ophthalmologist.
      • American Academy of Ophthalmology
      Policy Statement. An Ophthalmologist's Duties Concerning Postoperative Care.

       COUNSELING AND REFERRAL

      Childhood exotropia is a long-term problem that requires commitment from the patient and/or family/caregiver and ophthalmologist to achieve the best possible outcome. The ophthalmologist should discuss the findings of the evaluation with the patient, when appropriate, as well as the parent/caregiver. The ophthalmologist should explain the disorder and include the family in a collaborative approach to therapy. Parents/caregivers of pediatric patients who understand the diagnosis and rationale for treatment are more likely to adhere to treatment recommendations.
      • Newsham D
      A randomised controlled trial of written information: the effect on parental non-concordance with occlusion therapy.
      • Norman P
      • Searle A
      • Harrad R
      • Vedhara K
      Predicting adherence to eye patching in children with amblyopia: an application of protection motivation theory.

       SOCIOECONOMIC CONSIDERATIONS FOR STRABISMUS

      There is consensus that timely and appropriate eye care can significantly improve children's quality of life and can reduce the burden of eye disease. Timely treatment of strabismus relies on early diagnosis.
      • American Academy of Ophthalmology Pediatric Ophthalmology/Strabismus Panel
      Preferred Practice Pattern®. Pediatric Eye Evaluations.
      Therefore, early and regular vision screening are important to detect this and other conditions.
      Almost 40% of children 3 to 6 years of age or younger in the United States have never undergone a vision screening.
      • Agency for Healthcare Research and Quality
      National Healthcare Disparities Report, 2008.
      • Kemper AR
      • Wallace DK
      • Patel N
      • Crews JE
      Preschool vision testing by health providers in the United States: Findings from the 2006-2007 Medical Expenditure Panel Survey.
      Children in low-income families, in uninsured families, and in racial and ethnic minority groups may fare worse.
      • Agency for Healthcare Research and Quality
      National Healthcare Disparities Report, 2008.
      • Kemper AR
      • Wallace DK
      • Patel N
      • Crews JE
      Preschool vision testing by health providers in the United States: Findings from the 2006-2007 Medical Expenditure Panel Survey.
      • Flores G
      Committee on Pediatric Research
      Technical report–racial and ethnic disparities in the health and health care of children.
      • Majeed M
      • Williams C
      • Northstone K
      • Ben-Shlomo Y
      Are there inequities in the utilisation of childhood eye-care services in relation to socio-economic status? Evidence from the ALSPAC cohort.
      Studies indicate that African American children and children living below 400% of the federal poverty level receive fewer and less intensive services relative to their white counterparts.
      • Flores G
      Committee on Pediatric Research
      Technical report–racial and ethnic disparities in the health and health care of children.
      • Ganz M
      • Xuan Z
      • Hunter DG
      Patterns of eye care use and expenditures among children with diagnosed eye conditions.
      There is evidence that these race/ethnicity disparities are reflected in eye care services as well as in other health services.
      • Ganz M
      • Xuan Z
      • Hunter DG
      Patterns of eye care use and expenditures among children with diagnosed eye conditions.
      It is still unclear whether these disparities in eye care services are due to underdiagnosis and undertreatment of certain conditions in minority children, a lower prevalence of treatable eye conditions in certain populations, racial/ethnic differences in access to care or in preferences for treatment, or a combination of these factors.
      • Flores G
      Committee on Pediatric Research
      Technical report–racial and ethnic disparities in the health and health care of children.
      Barriers to eye care extend beyond inadequate screening and diagnosis. Few screening programs ensure access to eye examinations and treatment for children who fail screening. It appears from one large study that only about half of children who fail vision screening are seen by eye care providers in follow-up.
      • Donahue SP
      • Johnson TM
      • Leonard-Martin TC
      Screening for amblyogenic factors using a volunteer lay network and the MTI photoscreener. Initial results from 15,000 preschool children in a statewide effort.
      Barriers to care may include inadequate information, lack of access to care, and/or financial or insurance coverage difficulties.
      • Kemper AR
      • Uren RL
      • Clark SJ
      Barriers to follow-up eye care after preschool vision screening in the primary care setting: