Assessment of corneal epithelial thickness in dry eye patients.

ABSTRACT

PURPOSE: To investigate the features of corneal epithelial thickness topography with Fourier-domain optical coherence tomography (OCT) in dry eye patients. METHODS: In this cross-sectional study, 100 symptomatic dry eye patients and 35 normal subjects were enrolled. All participants answered the ocular surface disease index questionnaire and were subjected to OCT, corneal fluorescein staining, tear breakup time, Schirmer 1 test without anesthetic (S1t), and meibomian morphology. Several epithelium statistics for each eye, including central, superior, inferior, minimum, maximum, minimum - maximum, and map standard deviation, were averaged. Correlations of epithelial thickness with the symptoms of dry eye were calculated. RESULTS: The mean (±SD) central, superior, and inferior corneal epithelial thickness was 53.57 (±3.31) µm, 52.00 (±3.39) µm, and 53.03 (±3.67) µm in normal eyes and 52.71 (±2.83) µm, 50.58 (±3.44) µm, and 52.53 (±3.36) µm in dry eyes, respectively. The superior corneal epithelium was thinner in dry eye patients compared with normal subjects (p = 0.037), whereas central and inferior epithelium were not statistically different. In the dry eye group, patients with higher severity grades had thinner superior (p = 0.017) and minimum (p < 0.001) epithelial thickness, more wide range (p = 0.032), and greater deviation (p = 0.003). The average central epithelial thickness had no correlation with tear breakup time, S1t, or the severity of meibomian glands, whereas average superior epithelial thickness positively correlated with S1t (r = 0.238, p = 0.017). CONCLUSIONS: Fourier-domain OCT demonstrated that the thickness map of the dry eye corneal epithelium was thinner than normal eyes in the superior region. In more severe dry eye disease patients, the superior and minimum epithelium was much thinner, with a greater range of map standard deviation.