Longitudinal Changes in Corneal Epithelial and Central Corneal Thickness in Type 2 Diabetes Assessed by AS-OCT: A Real-World Study

İhsan Boyacı,1 Göktuğ Demirci21Department of Internal Medicine, Istanbul Medipol University Faculty of Medicine, Istanbul, Türkiye; 2Department of Ophthalmology, Istanbul Medipol University Faculty of Medicine, Istanbul, TürkiyeCorrespondence: İhsan Boyacı, Department of Internal Medicine, Istanbul Medipol University, Faculty of Medicine, Molla Gürani Mahallesi, Halıcılar Köşkü Sokak No: 11 Fatih, Istanbul, 34093, Türkiye, Tel +90 212 631 1522, Email [email protected]: To evaluate longitudinal changes in central corneal epithelial thickness (CCET) and central corneal thickness (CCT) using anterior segment optical coherence tomography (AS-OCT) over 12 months in adults with type 2 diabetes receiving one of two routinely prescribed oral antidiabetic regimens, and to explore their association with glycemic changes.Methods: In this retrospective observational cohort study, 40 adults with type 2 diabetes receiving one of two routinely prescribed treatment regimens (vildagliptin–metformin, n=19; empagliflozin–metformin, n=21) underwent AS-OCT at baseline, 3 months, and 12 months. Glycated hemoglobin and fasting plasma glucose were assessed at each visit. Precision analysis indicated detectable between-group differences of 4.7 μm for CCT and 6.1 μm for CCET.Results: Both groups showed significant within-group glycated hemoglobin improvement (mean reduction: − 2.28% and − 2.88% in the vildagliptin–metformin and empagliflozin–metformin groups, respectively; p< 0.05) without between-group differences. CCT and CCET showed no statistically detectable longitudinal change over 12 months, with no significant differences in longitudinal change between groups. Glycated hemoglobin change showed a modest independent association with CCT change (β = 0.81 μm per 1% glycated hemoglobin; 95% CI 0.20– 1.42; p=0.011; n=32).Conclusions: Corneal structural parameters showed no statistically detectable longitudinal change or between-group difference over 12 months. Given the modest sample size and observational design, these findings should be considered hypothesis-generating and require confirmation in larger prospective studies.Keywords: anterior segment optical coherence tomography, central corneal thickness, corneal epithelial thickness, glycemic control, type 2 diabetes