Early changes in diabetic retinopathy: capillary loss and blood-retina barrier permeability in relation to metabolic control.

In diabetic retinopathy capillary loss and blood-retina barrier leakage are prominent factors. We present a study with quantitative measurements of both capillary loss and leakage and their relation to cumulative metabolic control. Seventeen insulin-dependent diabetic patients with no retinopathy or only mild background retinopathy and 10 years' duration of the disease were included in the study. Status of metabolic regulation had been followed for at least 6 years. Seven healthy subjects were included as controls. In diabetic patients the perifoveal intervascular areas were found to increase significantly with the cumulative HbA1c index (p = 0.02) and in relation to the presence of moderate background retinopathy (p < 0.02). The blood-retina barrier leakage and the area of the foveal avascular zone were not significantly different from healthy subjects and no correlation was found between the HbA1c index and blood-retina barrier permeability. We conclude that perifoveal capillary loss occurs early in the course of diabetic retinopathy and that this loss is related to prior glycemic control and to the ophthalmoscopic retinopathy level.