Topographical Distribution of Retinal and Optic Disc Neovascularization in Early Stages of Proliferative Diabetic Retinopathy

Abstract

We analyzed the topography of proliferative diabetic retinopathy (PDR), and visualized the distribution of neovascularization of the optic disc (NVD) and elsewhere in the retina (NVE). The study included 174 eyes of 106 patients with early PDR. Data on the size and location of 391 NVE and 73 NVD were converted into a database of two-dimensional retinal and optic disc charts. The geometric centers of the neovascular lesions were plotted into corresponding areas of the charts, and the topographic distributions of the NVE and NVD were visualized by merging the charts and displaying the number of overlapping lesions on color-coded contour maps. A total of 141 (36%) NVE was located in the temporal and 250 (64%) in the nasal hemisphere (P < 0.0001). The distribution of the NVD in the temporal and nasal half of the optic disc was 46 (63%) and 27 (37%), respectively (P = 0.03). NVE in type 1 diabetes were located significantly farther from the fovea and optic disc, and were more numerous and larger than in type 2 diabetes. The number and diameter of the NVE were also significantly higher when the time from the last examination to the appearance of PDR exceeded 12 months. The majority of NVE lesions are located inferonasal to the optic disc and along the superior vascular arcades, while NVD have a predilection for the upper temporal disc rim. More extensive PDR is found in patients with type 1 diabetes and those with examination intervals longer than one year.