The relationships between risk factors and the distribution of retinopathy lesions in type 2 diabetes

PURPOSE: Previous studies have shown that the progression of diabetic retinopathy to vision-threatening lesions may be related to the development of retinopathy lesions in specific retinal areas. The purpose of the present study was to examine whether the occurrence of retinopathy in these retinal areas is related to known risk factors for progression of retinopathy in type 2 diabetes. METHODS: A total of 377 randomly selected patients with type 2 diabetes underwent examinations which included measurement of blood pressure, haemoglobin A1c and cholesterol, and a full eye examination including fundus photography. The fundus photographs were digitized and a computer-assisted technique was used to quantify retinopathy lesions in the macular area, around the vascular arcades and in the retinal periphery. Only the number of microaneurysms/haemorrhages was sufficient for statistical analysis. RESULTS: Patients with retinopathy had significantly longer diabetes duration, and higher blood pressure and HgbA1c than patients without retinopathy. However, among the patients with retinopathy there was no correlation between these risk factors and the overall number of microaneurysms/haemorrhages or the number of these lesions in the local areas of the fundus studied. CONCLUSIONS: The localized distribution of retinopathy lesions does not correlate with known risk factors and background factors for the development of diabetic retinopathy in the early stages of the disease. Future improvements of grading systems for diabetic retinopathy should focus on a quantification of the overall number and dynamics of retinopathy lesions in the early stages of retinopathy and the regional distribution and dynamics of lesions in more advanced stages of retinopathy.