Risk markers for progression of mild nonproliferative retinopathy to clinically significant macular edema in type 2 diabetic patients

Abstract

Purpose To determine risk markers for the development of clinically significant macular edema (CSME) needing photocoagulation treatment in type 2 diabetic patients with mild nonproliferative retinopathy (NPDR), during a 7-year period. Methods Fifty-one type 2 diabetic patients with mild NPDR, followed-up for 2 years as controls of diabetic retinopathy clinical trials, were selected. Patients underwent ophthalmological examinations every 6 months, including stereoscopic color fundus photography, fluorescein angiography and vitreous fluorophotometry, and were metabolically controlled. These patients were thereafter followed-up for the next 5 years by conventional general and ophthalmological care. Results At the end of the 7-year follow-up period, 8 patients developed CSME, needing photocoagulation treatment. These patients presented a higher microaneurysm (MA) formation rate at the first year of follow-up (p<0.001), a higher blood-retinal barrier (BRB) permeability value (p=0.042), an abnormal foveal avascular zone (FAZ) contour on fluorescein angiography (p=0.009) and a higher HbA1C level at baseline (p=0.001). Conclusion Microaneurysm formation rate higher or equal to 3 MA/year, BRB permeability values over or equal to 4.0 nm.s-1, evidence of abnormalities in the FAZ, and hemoglobin A1C levels at baseline, are risk markers for progression of NPDR to CSME in patients with type 2 diabetes.