Anterior segment optical coherence tomography analysis of regional epithelial thickness in keratoconus following intracorneal ring segment implantation

Abstract

Background The changes in the epithelial thickness profile were found to be highly predictable and were responding to compensate for the changes in stromal curvature gradient. Aim The aim of this study was to evaluate the epithelial thickness after intracorneal ring segment (ICRS) implantation in patients with keratoconus and to correlate it with the uncorrected visual acuity (UCVA). Patients and methods This is a prospective nonrandomized clinical study that was conducted at the Faculty of Medicine, Ain Shams University, Cairo, Egypt. It included 24 eyes with keratoconus, which were implanted by ICRS and were scanned by CIRRUS HD-OCT 5000 preoperatively, at 1 week, 1 month, and 3 months postoperatively. The mean epithelial thickness (MET) at the cone and at the zone of ICRS implantation (5–7 mm) and UCVA were documented. Results The MET increased significantly from a preoperative value of 42.9±6.3–50.8±7.1 µm at 3 months postoperatively (P=0.01). In addition, the mean minimum (and not the mean maximum) epithelial thickness at the 5–7-mm zone increased significantly from 35.8±4.2 µm preoperatively to 38.7±5.4 µm at 3 months postoperatively (P=0.000). There was a statistically significant negative correlation between the MET and the mean UCVA preoperatively (r=−0.389, P=0.03), at 1 week (r=−0.415, P=0.04), and at 3 months postoperatively (r=−0.479, P=0.01). Conclusions The significant increase in the MET indicates the immediate, dynamic epithelial remodeling that continued up to 3 months after implantation. The increase in the minimum but not the maximum epithelial thickness confirms the epithelial remodeling rather than hyperplasia. The MET can be a prognostic factor for the visual outcome after ICRS as it correlated with the UCVA.