Purpose
To compare small incision lenticule extraction (SMILE) versus LASIK for post-refractive
dry eye disease.
Design
Prospective, comparative, nonrandomized clinical study.
Participants
Thirty patients scheduled for bilateral myopic SMILE and 30 age-, sex-, and refraction-matched
patients scheduled for bilateral myopic LASIK were enrolled and followed for 6 months
after the surgery.
Methods
Complete evaluation of dry eye disease was performed at 1 and 6 months postoperatively,
which included vision-related quality of life (Ocular Surface Disease Index [OSDI]),
clinical examinations (tear film breakup time [TBUT], Schirmer I test, corneal staining),
and tear osmolarity measurements, together with an overall severity score. Function
and morphology of the corneal innervation were evaluated by corneal esthesiometry
and subbasal nerve imaging using in vivo confocal microscopy (IVCM).
Main Outcome Measures
Overall analysis of dry eye disease and corneal innervation.
Results
High incidence of mild to moderate dry eye disease was observed in both groups 1 month
postoperatively, which remained significantly higher in the LASIK group than in the
SMILE group 6 months after surgery (overall severity score [0–4]: 1.2±1.1 vs. 0.2±0.4,
respectively,
P < 0.01), leading to more frequent use of tear substitutes over the long term. Corneal
sensitivity was better in SMILE than in LASIK eyes 1 month postoperatively (3.5±1.79
vs. 2.45±2.48, respectively,
P < 0.01) and then recovered to statistically similar values at 6 months. Corneal nerve
density, number of long fibers, and branchings as assessed by IVCM were significantly
higher in the SMILE group compared with the LASIK group 1 and 6 months after surgery.
Corneal sensitivity was negatively correlated with dry eye-related corneal damage
(
R² = 0.48,
P < 0.01), and the long fiber nerve density was independently correlated with the OSDI
score (
R² = 0.50,
P < 0.01) and the Schirmer test (
R² = 0.21,
P < 0.01) 6 months postoperatively.
Conclusions
The SMILE procedure has a less pronounced impact on the ocular surface and corneal
innervation compared with LASIK, further reducing the incidence of dry eye disease
and subsequent degradation in quality of life after refractive surgery.
Abbreviations and Acronyms:
FLEX ( femtosecond lenticule extraction), IVCM ( in vivo confocal microscope), OCT ( optical coherence tomography), OSDI ( Ocular Surface Disease Index), SMILE ( small incision lenticule extraction), TBUT ( tear film breakup time)References
Eye health statistics at a glance. Compiled by American Academy of Ophthalmology. Available at: http://www.aao.org/newsroom/upload/Eye-Health-Statistics-April-2011.pdf. Updated April 2011. Accessed November 4, 2014.
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Article Info
Publication History
Published online: November 22, 2014
Accepted:
October 7,
2014
Received in revised form:
October 6,
2014
Received:
August 26,
2014
Footnotes
Financial Disclosure(s): The author(s) have made the following disclosure(s):
A.D.: Consultant – Alcon, Thea, Abbott Medical Optics, Bausch & Lomb; Grants/grants pending – INSERM and UPMC University Paris 6; Inventor – 2 patents belonging to INSERM. C.B.: Board member and consultant – Alcon, Allergan, MSD, Thea, Santen; grants/grants pending – Allergan, MSD, Thea, Santen; Co-inventor – 2 patents belong to INSERM.
Public grant from the French National Institute of Health and Medical Research. The funding organization had no role in the design or conduct of this research.
Identification
Copyright
© 2015 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.
