Ocular Surface Epithelial Thickness Evaluation in Dry Eye Patients: Clinical Correlations

Purpose. To evaluate the relationship between corneal and conjunctival epithelium thickness and ocular surface clinical tests in dry eye disease (DED) patients. Patients and Methods. Fifty-four patients with DED and 32 control subjects were included. Each patient underwent an ocular surface evaluation using the ocular surface disease index (OSDI), tear film break-up time (TBUT), corneal and conjunctival staining, tear film lipid layer analysis, and Schirmer test. The central corneal (CET), limbal (LET), and bulbar conjunctival epithelium thickness (BET) were acquired using spectral-domain optical coherence tomography (SD-OCT). Results. Compared to control subjects, mean BET was significantly thicker and mean LET was significantly lower in the DED group. There was no significant difference in mean CET between the two groups. The mean LET was correlated with OSDI and TBUT. The inferior LET was correlated with OSDI, Schirmer I test, TBUT, Oxford score, and corneal sensitivity. Mean BET was correlated with OSDI and TBUT, but not with Schirmer I test and Oxford score. Conclusions. In dry eye patients, a thinner limbal epithelium and a thicker bulbar conjunctival epithelium were observed. These changes were correlated to the severity of dry eye symptoms and tear film alterations.