Prospective Evaluation Of The Effect Of Corneal Collagen Cross-Linking On Limbal Epithelial Thickness In Keratoconus

This study aimed to evaluate the changes in corneal limbal epithelial thickness (LET) in patients who underwent accelerated corneal collagen cross-linking (CXL) (18 mW/cm² for 5 minutes) due to progressive keratoconus (KC).

The study was conducted at the Cornea and Ocular Surface Diseases Unit of the Department of Ophthalmology, Balikesir University. Keratoconus was diagnosed by an experienced cornea specialist, and corneal cross-linking (CXL) was performed in patients who demonstrated progression during follow-up.

Best-corrected visual acuity (BCVA), central corneal thickness (CCT), and manual limbal epithelial thickness (LET) measurements in the nasal and temporal quadrants were obtained using an anterior segment optical coherence tomography device (AS-OCT, AngioVue, Freemont, CA) before corneal collagen cross-linking and on postoperative day 1, week 1, and month 1. The average epithelial thickness located along a line drawn 1 mm centrally from the scleral spur at the corneoscleral transition zone was defined as ‘limbal epithelial thickness.’ These measurements were recorded separately for the nasal and temporal quadrants, and values from all visits were compared.

A total of 10 eyes from 10 patients (8 males, 2 females) with a mean age of 19.1±3.6 years were included in the study. Preoperative BCVA was 0.53±0.33 and 0.52±0.30 at the 1-month visit (p=0.598). Preoperative, postoperative day 1, week 1, and month 1 LET measurements were as follows: in the temporal quadrant, 62.8±4.6 µm, 65.6±6.9 µm, 64.7±3.0 µm, and 65.8±3.7 µm; and in the nasal quadrant, 59.8±4.0 µm, 63.8±3.8 µm, 64.5±2.8 µm, and 64.7±2.6 µm, respectively. A significant difference between visits was observed only between the week 1 and month 1 measurements in both the temporal and nasal quadrants (p=0.007 and p=0.009, respectively). No significant difference was found in CCT measurements across visits (p>0.05).

In corneal CXL treatment, no acute alteration occurs in the limbal epithelium due to the protection of the limbal region from UV exposure. The change observed around the first month after treatment is not directly related to the procedure itself and may instead be associated with ocular surface inflammation.