Corneal Structural Alterations Under Chronic Hyperglycemia: Biomechanical and Densitometric Insights in Type 2 Diabetes with and Without Retinopathy

OBJECTIVES: Objectives: To evaluate and compare corneal biomechanical properties and densitometry in healthy individuals and type 2 diabetic patients, with and without non-proliferative diabetic retinopathy (NPDR), and to investigate potential associations with glycemic control.
METHODS: This prospective, observational study included 61 diabetic patients (30 without DR and 31 with NPDR) and 76 healthy controls. Comprehensive ophthalmic examinations were performed for all participants, including Corvis ST for corneal biomechanical assessment and Scheimpflug-based densitometry. Glycated hemoglobin (HbA1c) and blood glucose levels were recorded in the diabetic group. Patients with proliferative DR were excluded to maintain more homogeneous cohorts.
RESULTS: Diabetic patients demonstrated significantly higher stiffness parameters (stress–strain index) and corneal densitometry compared with healthy controls (p<0.001). In subgroup analyses, the tomographic biomechanical index (TBI) was lower among diabetic patients with retinopathy than those without (p=0.036), suggesting an additional impact of retinopathy on corneal biomechanics. Moderate correlations were identified between HbA1c and specific corneal deformation parameters, highlighting the influence of metabolic control on corneal properties. Blood glucose levels exhibited a moderate positive correlation with TBI (p=0.033).
DISCUSSION AND CONCLUSION: Corneal biomechanics and densitometry differ significantly between diabetic patients and healthy controls, with further alterations in those with non-proliferative retinopathy, and these changes may correlate with glycemic control.

Keywords: Corneal biomechanics, corneal densitometry, corvis ST, Type 2 diabetes mellitus