The effect of corneal collagen cross-linking on confocal microscopic findings and tear indices in patients with progressive keratoconus

This study was performed to evaluate changes in tear indices and confocal microscopic findings after corneal collagen cross-linking (CXL) in patients with progressive keratoconus in Farabi Hospital in Tehran, Iran, during 2012-2013. In this analytical study, 32 consecutive eyes of 23 patients (mean age of 20.91 years) with progressive keratoconus were enrolled. The standard cross-linking surgery was performed for all patients. Visual, refractive and topographic evaluations were done before and 6 months after the surgery. Tear function tests and confocal microscopic examination were performed before and 1 month and 6 months after the procedure using the paired t-test with SPSS software. Using the 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 statistically significant between 1 month and 6 months after CXL (P<0.05). No statistically significant change was noted in the number of the endothelial cells and polymegathismt after 6 months follow-up. Significant improvement was noted in uncorrected visual acuity, best corrected visual acuity, flattest corneal meridian and maximum keratometry in pentacam after 6 months of the procedure. Corneal collagen cross-linking can cause a significant reduction in subepithelial nerve plexus and significant alterations in keratocyte density in anterior and middle stroma.