Effect of Corneal Collagen Cross-Linking on Corneal Innervation, Corneal Sensitivity, and Tear Function of Patients with Keratoconus

Abstract

To evaluate the effect of corneal collagen cross-linking (CXL) on corneal innervation, corneal sensitivity, and tear function in patients with keratoconus. Prospective, interventional case series. Twenty-four patients with bilateral keratoconus (30 eyes) who presented to the Institute of Vision and Optics, University of Crete, from May 2008 to October 2008. Patients underwent CXL. Confocal microscopic analysis of corneal sub-basal nerve plexus (total nerve length per image), corneal sensitivity (assessed with the Cochet-Bonnet esthesiometer), basic tear secretion (assessed with Schirmer's I test with anesthesia), and tear film stability (evaluated by means of tear film break-up time [TFBUT]) were assessed preoperatively and at 1, 3, 6, 9, 12, 18, and 24 months postoperatively. Comparisons between preoperative and each postoperative value of total nerve length per image, corneal sensitivity, Schirmer's I test results, and TFBUT. Total nerve length per image and corneal sensitivity were significantly decreased until postoperative month 6 (for both parameters: P<0.05 paired-samples t test at 1, 3, and 6 months postoperatively). Total nerve length per image tended to increase up to 2 years postoperatively, when it reached the preoperative level, but differences with the preoperative values after the sixth post-CXL month were insignificant. The results of Schirmer's I test and TFBUT had no statistically significant difference at any time point. A transient decrease in corneal innervation and corneal sensitivity can be observed up to 6 months after CXL. No significant effect of CXL could be detected on basic tear secretion and tear film stability in our group of patients. The author(s) have no proprietary or commercial interest in any materials discussed in this article.