Ultrastructural Changes in OCT and Refractive Differences after Refractive Lens Exchange Surgery

Abstract

Purpose : Refractive surprise is a known risk of refractive lens exchange surgery. In this manuscript we hope to utilize the power of big data analysis to identify risk factors for refractive differences in conjunction with analysis of peri-operative Spectral Domain Ocular Coherence Tomography (OCT) data in a large cohort of refractive lens exchange patients in the United Kingdom.

Methods : A retrospective chart review was performed upon 11,063 visual outcomes from 46 monofocal, toric, & multifocal lens models with an attendant 11,063 pre-operative Cirrus SD-OCT scans and 3,622 matched post-operative OCTs. Linear mixed effects model regression and analysis of variance were employed to evaluate possible predictors of refractive difference (defined as actual minus targeted post-operative spherical equivalent) and change in Central Macular Thickness (CMT) with and without logarithmic transformation.

Results : CMT at least 6 months after cataract surgery was significantly changed from pre-operative CMT by a mean of 33 micrometers. Changes in CMT were significantly correlated with worse visual outcomes, and pre-surgical CMT was also significantly correlated with change in Best Corrected Visual Acuity and change in Uncorrected Distance Visual Acuity. Of 46 IOL models analyzed 4 of the multi-focal IOL models, 1 toric monofocal model, and 1 non-toric monofocal model were found to have significant refractive differences, and this effect was modified by change in CMT. Patients who received these lenses were more likely to state that they would not do-over their surgery if given the option (OR 1.2:1). Choice of lens power formula was not independantly associated with refractive differences.

Conclusions : Retinae in our large cohort demonstrated ultrastructural changes after refractive lens exchange surgery. These changes do not appear to be associated with choice of traditional or presbyopia-correcting surgery, however a number of lens models are identified in our analysis as more frequently having off-target post-operative refraction with third- and fourth-generation lens power calculations. The amount of refractive difference associated with choice of lens model is partially mediated by changes in retinal thickness. Standard pre-operative and post-operative OCT scans may be valuable for lens selection, routine clinical care, and for monitoring causes of refractive differences.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.