Corneal Epithelial Thickness Mapping In Different Refractive Groups Using Anterior Segment Optical Coherence Tomography

To evaluate the relationship between refractive error and corneal epithelial thickness distribution in healthy eyes using anterior segment optical coherence tomography (AS-OCT).

Department of Ophthalmology, Ege University, Izmir, Turkiye.

This cross-sectional study included 64 eyes of 32 participants with no ocular pathology, no contact lens or topical medication use. BCVA was 20/20. Refractive status was expressed as spherical equivalent (SE) and categorized into three groups (Group 1: +1.00 to −0.50 D, n=34; Group 2: −0.51 to −2.00 D, n=18; Group 3: ≤ −2.00 D, n=12). Corneal epithelial thickness was measured using the Anterion (Heidelberg Engineering, Heidelberg, Germany) AS-OCT system. Parameters included mean (mET), maximum (maxET), minimum (minET) epithelial thickness, inferior–superior difference (ISD), maximum–minimum difference (MMD), and epithelial thickness in concentric rings (0–2, 2–4, 4–6, 6–7 mm). Measurements were compared among groups.

The mean age of the 32 participants (16 males, 16 females) was 31.6±9.7 years. Mean mET was 49.5±2.9 µm, 48.4±2.5 µm, and 48.6±3.2 µm (p=0.346); mean maxET was 55.8±3.8 µm, 54.4±2.8 µm, and 54.3±3.1 µm (p=0.264); and mean minET was 42.9±3.1 µm, 42.3±2.4 µm, and 42.1±3.4 µm (p=0.633) in Groups 1, 2, and 3, respectively, with no significant differences. ISD was 1.3±2.0 µm, 0.7±1.8 µm, and 1.4±1.1 µm (p=0.519), and MMD was 12.9±3.2 µm, 12.1±2.5 µm, and 12.2±2.0 µm (p=0.690) in Groups 1, 2, and 3, respectively, showing no significant intergroup differences. Analysis of epithelial thickness in concentric rings also demonstrated no significant intergroup differences in any zone (0–2 mm: p=0.224; 2–4 mm: p=0.211; 4–6 mm: p=0.254; 6–7 mm: p=0.298).

Based on the present findings, corneal epithelial thickness distribution does not exhibit significant refractive status–dependent variations within the studied range in healthy eyes. Intergroup differences observed in mET, maxET, and minET, as well as within the concentric epithelial zones, were not significant. Similarly, the lack of significant differences in ISD and MMD indicates that refractive error is not associated with epithelial irregularity in the absence of organic corneal pathology. Overall, these findings indicate that refractive error does not significantly modulate epithelial thickness profiles and preserves epithelial regularity.