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Re: Chiang et al.: International Classification of Retinopathy of Prematurity, Third Edition (Ophthalmology. 2021;128:e51–e68)

Published:November 26, 2021DOI:https://doi.org/10.1016/j.ophtha.2021.10.021
      To the Editor:
      In their article, Chiang et al
      • Chiang M.F.
      • Quinn G.E.
      • Fielder A.R.
      • et al.
      International classification of retinopathy of prematurity, third edition.
      have updated the International Classification of Retinopathy of Prematurity (ICROP) to improve objectivity of finding, as well as to encompass clinical variations observed in regression or reactivation of retinopathy of prematurity (ROP), particularly after treatment with anti-vascular endothelial growth factor. The authors have subclassified zone II as anterior and posterior to identify the more serious disease in posterior zone II. However, the standard of care for the disease in both the zones is likely to be laser photocoagulation. To best of our knowledge, there is currently no study that has attempted to compare the outcomes of treatment between the anterior and posterior locations of zone II. In contrast, ROP in zone I, particularly posterior zone I, has been shown to have poor structural outcomes with laser monotherapy as opposed to a combination therapy with anti vascular endothelial growth factor and laser photocoagulation.
      • Shah P.K.
      • Narendran V.
      • Saravanan V.R.
      • et al.
      Fulminate retinopathy of prematurity - clinical characteristics and laser outcome.
      ,
      • Parchand S.M.
      • Agrawal D.
      • Gangwe A.
      • et al.
      Combined intravitreal ranibizumab and zone I sparing laser ablation in infants with posterior zone I retinopathy of prematurity.
      Kychenthal et al
      • Kychenthal A.
      • Dorta P.
      • Katz X.
      Zone I retinopathy of prematurity: clinical characteristics and treatment outcomes.
      have defined posterior zone I as a circular area centered on the optic nerve head, with a radius being the distance between the center of the optic disc and the fovea. However, this subdivision of zone II has not been used universally for documentation, sometimes referred to as the half zone. We suggest, similar to zone II, that zone I also be subdivided into anterior and posterior with reference to the fovea. This subdivision will not only ensure the objectivity of documentation of disease involving zone I, it will also have direct implications for deciding the appropriate treatment and prognosis based on currently available evidence.
      In the current classification, aggressive posterior ROP (APROP) has been replaced by aggressive ROP. For this change, the authors have cited a series of “fulminate ROP” by Shah et al.
      • Shah P.K.
      • Narendran V.
      • Saravanan V.R.
      • et al.
      Fulminate retinopathy of prematurity - clinical characteristics and laser outcome.
      The description of fulminate disease given by the authors in this article is very typical of APROP as described in ICROP 2. In their description, it is a disease that usually occurs within a definite zone, extending nasally 2 to 3 diameters from the disc margin and edge of the macula temporally. This area roughly corresponds with posterior zone I as described by Kychenthal et al.
      • Kychenthal A.
      • Dorta P.
      • Katz X.
      Zone I retinopathy of prematurity: clinical characteristics and treatment outcomes.
      The average gestational age and birth weight of infants in this series was more than typically described for fulminate ROP by others authors. Shah et al concluded that the zone I ROP occurred in babies with higher gestational ages and birth weights in India than in Western countries. We feel the word "posterior" in APROP can be retained because it is an integral part of disease description.
      A clinical scenario wherein features of both aggressive and typical staged ROP are seen in the same eye has been reported. This has been labelled hybrid ROP and is reported in developing countries like India, which may possibly reflect neonatal care received by the infant.
      • Sanghi G.
      • Dogra M.R.
      • Dogra M.
      • et al.
      A hybrid form of retinopathy of prematurity.
      Improving the survival rates of preterm babies in middle income or developing countries has largely contributed to a third epidemic of ROP, where this clinical scenario is often reported. We suggest the clinical entity hybrid ROP may be incorporated in ICROP 3. Alternately, the authors can add guidelines for reporting and documentation of such an entity. This shall enable the ICROP 3 to be truly international.

      References

        • Chiang M.F.
        • Quinn G.E.
        • Fielder A.R.
        • et al.
        International classification of retinopathy of prematurity, third edition.
        Ophthalmology. 2021; 128: e51-e68
        • Shah P.K.
        • Narendran V.
        • Saravanan V.R.
        • et al.
        Fulminate retinopathy of prematurity - clinical characteristics and laser outcome.
        Indian J Ophthalmol. 2005; 53: 261-265
        • Parchand S.M.
        • Agrawal D.
        • Gangwe A.
        • et al.
        Combined intravitreal ranibizumab and zone I sparing laser ablation in infants with posterior zone I retinopathy of prematurity.
        Indian J Ophthalmol. 2021; 69: 2164-2170
        • Kychenthal A.
        • Dorta P.
        • Katz X.
        Zone I retinopathy of prematurity: clinical characteristics and treatment outcomes.
        Retina. 2006; 26: S11-S15
        • Sanghi G.
        • Dogra M.R.
        • Dogra M.
        • et al.
        A hybrid form of retinopathy of prematurity.
        Br J Ophthalmol. 2012; 96: 519-522

      Linked Article

      • International Classification of Retinopathy of Prematurity, Third Edition
        OphthalmologyVol. 128Issue 10
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          The International Classification of Retinopathy of Prematurity is a consensus statement that creates a standard nomenclature for classification of retinopathy of prematurity (ROP). It was initially published in 1984, expanded in 1987, and revisited in 2005. This article presents a third revision, the International Classification of Retinopathy of Prematurity, Third Edition (ICROP3), which is now required because of challenges such as: (1) concerns about subjectivity in critical elements of disease classification; (2) innovations in ophthalmic imaging; (3) novel pharmacologic therapies (e.g., anti–vascular endothelial growth factor agents) with unique regression and reactivation features after treatment compared with ablative therapies; and (4) recognition that patterns of ROP in some regions of the world do not fit neatly into the current classification system.
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        Ophthalmology
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          We appreciate the thoughtful suggestions of the authors. The International Classification of Retinopathy of Prematurity, 3rd Edition (ICROP3), group was an international committee of ophthalmologists from 6 continents who aimed to provide a globally acceptable terminology.1 The goal of the committee was to identify key changes that would balance responding to clinical needs and supporting future research studies, while minimizing increases to the complexity of clinical practice.
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