Biometric Determinants of Epithelial Thickness Profile Across a Wide Range of Refractive Errors

To evaluate the corneal epithelial thickness (CET) profiles and their correlations with axial length (AL) and anterior corneal radius of curvature (Rm F) across different refractive error groups.

A total of 1225 eyes of 616 normal patients were included. CET mapping, AL, and Rm F were obtained using spectral-domain optical coherence tomography, optical biometry, and Scheimpflug corneal tomography, respectively. In the CET map, one central (2 mm), eight paracentral (2–5 mm), and eight peripheral (5–6 mm) quadrants were evaluated separately. The subjects were divided into four groups based on their refractive status: hyperopia (spherical equivalent [SE] ≥  +0.50 D), emmetropia (SE >  −0.50 D and <  +0.50 D), low myopia (SE ≤ −0.50 D and >  −3.0 D), and moderate–high myopia (SE ≤ −3.0 D) groups. Linear mixed model analysis with Bonferroni correction was used to compare CET according to refractive error groups. The correlations between the CET profile and the AL and Rm F were analyzed.

The central CET was 53.7 ± 3.3 μm in hyperopia (n = 34), 53.2 ± 2.9 μm in emmetropia (n = 353), 52.8 ± 2.9 μm in low myopia (n = 677), and 52.0 ± 3.1 μm in moderate–high myopia (n = 161). Although thinning was observed in CET in all quadrants from hyperopia to moderate–high myopia, it was only significant in the superior and superonasal quadrants at the 2–5 mm and 5–6 mm-diameter rings. While AL and CET were significantly positively correlated (r range 0.17–0.28) in the moderate–high myopia group, Rm F and CET were significantly positively correlated (r range 0.08–0.10) in the low and moderate–high myopia groups.

CET varied according to different refractive error groups and was positively correlated with AL and Rm F, particularly in the moderate–high myopia group.