Effect of age and pre-operative corneal topography on epithelial thickness changes after corneal crosslinking and intrastromal corneal ring segment implantation.

Abstract

Purpose : Pre-operative factors that can predict changes caused by corneal crosslinking (CXL) and CXL plus intrastromal ring segment implantation (CXL+ICRS) surgeries could be used to help guide treatment decisions and maximize surgery outcomes. The purpose of this study is to investigate whether age and baseline corneal topography measurements affect epithelial thickness changes from CXL and CXL+ICRS procedures.

Methods : 19 eyes with keratoconus from 19 subjects were imaged with a Scheimpflug topographer and a research grade swept-source optical coherence tomographer (SS-OCT) no more than one month prior to receiving CXL surgery and again one year later. 11 eyes received CXL surgery and 8 eyes received CXL+ICRS surgery. The pre-operative thicknesses of the cornea and epithelial layer at the point of minimum total corneal thickness were acquired from the SS-OCT images using custom processing software. Regression analysis was performed to determine predictive factors for epithelial thickness changes one year after surgery.

Results : For the CXL only group, the mean pre-operative corneal epithelial thickness (54.7±3.3µm) was not significantly different than the epithelial layer thickness at the 1 year follow-up (54.9±2.6µm; p=0.82). For the CXL+ICRS group, the mean pre-operative epithelial thickness (55.6±5.0µm) was significantly greater than the same measurement at one year (50.5±4.4µm; p=0.01). The pre-operative factors of Kmax, flat K, steep K, epithelial thickness, minimum total corneal thickness and age were not predictive for changes in epithelial thickness for the CXL only group (p>0.05 for all). For the CXL+ICRS group, a thicker epithelium pre-operatively was predictive for less epithelial thinning post-operatively (R²=0.42, p=0.03). The other pre-operative factors did not correlate well (p>0.05 for all).

Conclusions : Corneas with smaller epithelial thickness measurements are more likely to show more epithelial thinning one year after CXL+ICRS surgery. However, for eyes in the CXL group, the mean pre-operative corneal epithelial thickness was not significantly different than the one year post-operative thickness. Age, Kmax, flat K, steep K, and minimum total corneal thickness before surgery are not predictive for epithelial thickness changes after surgery.

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