CORNEAL AND EPITHELIAL THICKNESS PROFILE IN EYES WITH DIFFERENT REFRACTIVE ERRORS

To evaluate corneal and epithelial thickness profile across different refractive error groups.

Department of Ophthalmology, Mater University Hospital, Dublin, Ireland

Eye Center, Mater Private, Dublin, Ireland

A total of 290 eyes were evaluated and divided in 3 groups according to their spherical equivalent (SE): high myopes (SE ≥ ̶ 5 D), n = 40, mild myopes (0 D < SE < ̶ 5 D), n = 204 , and hyperopes (SE > 0 D), n = 50. Epithelial and corneal mapping was obtained using Placido disk corneal topography with high-resolution OCT-based anterior segment tomography (MS-39®, Costruzione Strumenti Oftalmici, Florence, Italy).

There was a statistically significant decrease of epithelial thickness with distance from corneal apex (two-way ANOVA, F(2,578) = 14.90, p<0.001, ƞ_p² =0.12) and with refractive error (two-way ANOVA, F(2,578) = 3.66, p=0.042, ƞ_p² =0.25). With regards to corneal thickness, a statistically significant increment of corneal thickness with distance from corneal apex was seen (two-way ANOVA, F(2,578) = 98.71, p<0.001, ƞ_p² =0.19), independently of the refractive status (two-way ANOVA, F(2,578) = 1.89, p=0.17, ƞ_p²=0.12). In all three refractive groups, epithelial thickness is thinnest in the superior and superotemporal sectors (resp 48±4 μm and 49±4 μm), and the thickest in the inferior and nasal sectors (resp 54±4 μm and 54±3 μm). 

The corneal epithelium becomes progressively thinner from hyperopia to myopia, but refractive error does not impact the overall corneal thickness. Regardless of the refractive group, the corneal epithelium is the thinnest in the superior and superotemporal sections, while the nasal and inferonasal sections are the thickest.