Evaluation of the corneal epithelium in non-Sjögren’s and Sjögren’s dry eyes: an in vivo confocal microscopy study using HRT III RCM

BACKGROUND: The corneal epithelium is directly affected in dry eye syndrome. Thus, we attempted to describe the morphological features and evaluate the cellular density within the corneal epithelial layers in patients with non-Sjögren’s (NSDE) and Sjögren’s syndrome dry eyes (SSDE) by in vivo confocal microscopy (IVCM). METHODS: Central cornea was prospectively imaged by IVCM in 68 clinically diagnosed aqueous tear-deficient dry eyes and 10 healthy age-matched control eyes. Morphological characteristics of corneal epithelial layers and cellular densities were evaluated by four trained graders from the Doheny Eye Institute. RESULTS: Corneal epithelium in dry eyes presents morphological changes such as areas of enlarged and irregular shaped cells. In comparison with controls, the density of superficial epithelial cells was decreased in both the NSDE (P < 0.05) and SSDE groups (P < 0.01); the density of the outer layer of wing cells was smaller but not significantly different in NSDE (P > 0.05), but was lower in the SSDE group (P < 0.01); the density of the inner layer of wing cells was decreased in both the NSDE (P < 0.05) and SSDE groups (P < 0.01) and the density of basal epithelial cells was lower in both the NSDE (P < 0.01) and SSDE groups (P = 0.01). For all cell counts, the interclass correlation coefficient showed good agreement between graders (ICC =0.75 to 0.93). CONCLUSIONS: IVCM represents a reliable technique for examining the corneal epithelial microstructural changes associated with dry eyes, as well as for objectively and reproducibly quantifying cell densities within all corneal epithelial layers.