PURPOSE: To analyze the relationship between the extent of retinal ischemia in proliferative diabetic retinopathy and angle neovascularization.

METHODS: Panoramic fundus fluorescein angiography and 360-degree fluorescein gonioangiography to detect the angle neovascularization were performed on 70 eyes of 46 patients with proliferative diabetic retinopathy. Statistical significance was evaluated by chi-squared test. Statistical significance was evaluated if the value (T) was greater than the level of significance, χ_0.05²(2) = 5.99.

RESULTS: Retinal ischemia in fluorescein angiography was evaluated in four areas: capillary occlusion in (1) temporal raphe; (2) radial peripapillary capillaries; (3) the midperiphery (grade I, less than 25% of the area; grade II, 25% to 50%; grade III, 50% to 75%; grade IV, more than 75%); and (4) optic disk with neovascularization. The angle neovascularization was divided into two types: type I (14 eyes) and type II (12 eyes). Capillary occlusion in the temporal raphe and radial peripapillary capillaries, and papillary leakage significantly increased the risk of angle neovascularization (T = 8.28, 10.04, 6.44 respectively). Grade III and IV capillary occlusion in the midperiphery had a significant risk of angle neovascularization when compared with grade I (between grade III: T = 9.03, grade IV: T = 19.36) and II (between grade III: T = 6.31, grade IV: T = 16.09).

CONCLUSION: Risk factors for angle neovascularization were retinal nonperfusion in the midperiphery wider than grade III, capillary occlusion in the radial peripapillary capillaries and temporal raphe, and optic disk. Fluorescein gonio angiography was found to be a powerful tool for the early detection of angle neovascularization, especially in dark irides.