The Effect of Glycemia on Choroidal Thickness in Different Stages of Diabetic Retinopathy

The purpose of this study was to evaluate the influence of renal and glycemic parameters on choroidal thickness (CT) in patients with diabetes with and without diabetic retinopathy (DR).

This cross-sectional study included patients with and without diabetes. Patients underwent comprehensive ocular examination. CT was obtained using spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging (EDI) mode. Clinical parameters were body mass index, mean arterial pressure, glycated hemoglobin, fasting plasma glucose, estimated glomerular filtration rate, and capillary plasma glucose (CPG) a few minutes before EDI-SD-OCT.

The study included 275 participants: 42 with diabetes and no DR, 43 with mild nonproliferative diabetic retinopathy (NPDR), 46 with moderate NPDR, 39 with severe NPDR, 24 with proliferative diabetic retinopathy (PDR), 40 with previous panretinal photocoagulation (PRP) treatment for DR, and 41 without diabetes. The diabetic patients had thinner subfoveal CT than the nondiabetic participants (280.5 ± 83.4 vs. 327.1 ± 48.8 µm, p < 0.001). After multivariable adjustment, CT was significantly correlated with age, DR stage, and CPG. In patients with mild and moderate NPDR, a higher level of CPG was associated with thicker CT. This relationship was not found in patients with PDR.

CPG had the strongest correlation with CT in patients with NPDR (mild, moderate, and severe), but not in PDR and PRP PDR patients. Our study suggests that the glucose level at the time of the test should be aggregated to other systemic and ocular parameters, such as age and axial length, when studying the choroid using SD-OCT.