The influence of chronic diabetes mellitus on the thickness and the shape of the anterior and posterior surface of the cornea

Purpose: To determine the influence of diabetes mellitus (DM) type I and type 2 on the thickness, radius of curvature, power, and asphericity of the cornea. Methods: In this observational cross-sectional study, 102 patients with DM type 1, 10 1 patients with DM type 2, and 69 healthy subjects were measured by means of Scheimpflug imaging to determine central corneal thickness and the radius and asphericity of the anterior and posterior comeal surfaces. Corneal power was calculated from these parameters. Several systemic parameters (eg, duration of diabetes, glycated hemoglobin, blood glucose levels, and type of medication) and ocular comorbidity (eg, stage of retinopathy) were recorded. Results: Patients with DM type 1 and 2 had significantly smaller posterior corneal radii (P < 0.05) than those of healthy subjects (men: 6.49/6.48/6.64 mm; women: 6.36/6.30/6.49 mm). As a result, the optical power of the posterior corneal surface of the patients with diabetes differed from that of the healthy subjects (P < 0.01; men: DM, -6.2 D; healthy, -6.0 D; women: DM, -6.3 D; healthy, -6.2 D). However, comeal thickness, anterior radius and asphericity, and overall comeal power did not differ significantly between the groups. Furthermore, none of the systemic factors or ocular comorbidity had any influence on the corneal thickness or shape. Conclusions: DM affects the posterior corneal radius, resulting in a small change in posterior comeal power. However, chronic DM does not seem to significantly influence the overall comeal power.