Comparison of Corneal Epithelial and Stromal Thickness between Keratoconic and Normal Eyes in an Asian Population

Abstract

Purpose: To assess corneal epithelial and stromal thickness in keratoconic and normal eyes by spectral domain optical coherence tomography (SDOCT) in an Asian population. Methods: Forty-three keratoconic and 24 normal eyes were studied and examined using SDOCT. Keratoconic eyes with corneal scarring were excluded. Epithelial and stromal thickness was assessed at 25 points, 0.5 mm apart, across the central 6 mm of the pupil centre in the horizontal and vertical meridians. The correlation between epithelial and stromal thickness in both keratoconic and normal eyes (at the corneal centre) was also assessed. Results: The corneal epithelium at the pupil centre was significantly thinner in keratoconic eyes (p < 0.05) than in controls. Epithelial thickness varied widely in keratoconic eyes compared to controls (p < 0.05). The epithelium and stroma were significantly thinner inferiorly and temporally in keratoconic eyes (p < 0.05). There was a significant correlation between epithelial and stromal thickness (at the pupil centre) in the keratoconus group (r_s = 0.348, p < 0.001) but not the normal group (r_s = 0.036, p = 0.376). Conclusions: Corneal epithelial thickness was markedly thinner and varied in keratoconic eyes compared to controls. Epithelial thinning occurred secondary to the abnormal elevation of the stroma. These findings are useful in detecting early keratoconus and in the evaluation of refractive surgery candidates.