Effects of corneal collagen crosslinking on confocal microscopic findings and tear indices in patients with progressive keratoconus

Abstract

Background:To evaluate any change in tear indices and confocal microscopic findings after corneal collagen crosslinking (CXL) in patients with progressive keratoconus.Methods:Thirty-two consecutive eyes from 23 patients having progressive keratoconus were enrolled in this prospective, interventional cohort study. The standard crosslinking surgery was performed for all patients. Visual, refractive, and topographic evaluations were done before and at 6 months after surgery. Tear function tests and confocal microscopic examination were performed before and at 1 month and 6 months after the procedure.Results:There was no significant change in Schirmer-1 test results and tear osmolarity at 1 month and 6 months after CXL. Using confocal microscopy, all eyes showed reduced or absent subepithelial nerve plexus. Differences in basal epithelial cell density, epithelial mean cell area, and keratocyte density in anterior and middle stroma and endothelial cell pleomorphism were all significant at 1 month and 6 months after CXL (P < 0.05). No significant change was noted in endothelial cell count and their polymegathism at 6 months follow-up. Significant improvement was noted in uncorrected visual acuity, best corrected visual acuity, flattest corneal meridian (K2), and maximum keratometry in Pentacam (Kmax) after 6 months of the procedure.Conclusions:While CXL would have no effect on tear indices and endothelial cell count, it can cause a significant reduction in subepithelial nerve plexus and significant alterations in epithelial cell density in the anterior and middle stroma.

Early evaluation of corneal collagen crosslinking in ex-vivo human corneas using two-photon imaging

“…The first examination is performed not earlier than a one month after CXL. The outcome of CXL can also be assessed, several weeks after treatment, based on in vivo confocal microscopy (IVCM) by evaluating the corneal stroma reflectivity, corneal edema, and keratocyte apoptosis 1,14–16 , or based on anterior-segment optical coherence tomography (AS-OCT) through the detection of a hyperreflective line, i.e ., the “corneal demarcation line”, which marks the transition between CXL and non-CXL areas 17–19 .…”