A recent study found that peripheral ischemia is an important factor for proliferative changes in diabetic retinopathy (DR) and the presence of nonperfusion signifies the development of optic disc neovascularization.

The amount of retinal nonperfusion on fluorescein angiography also helps explain why some patients develop neovascularization only on the optic disc and others do elsewhere as the first manifestation of proliferative DR.

Researchers evaluated the association between retinal nonperfusion and DR severity on baseline ultra-widefield fluorescein angiograms in 92 patients: 59 in the proliferative group and 33 in the nonproliferative group. Regarding neovascularization location, 40 had it elsewhere and 19 had neovascularization of the optic disc with or without it elsewhere.

The study identified a retinal nonperfusion threshold of 118.3 disc areas (DA) with a specificity of 84.9% for proliferative DR. The median area of retinal nonperfusion was 67.8 DA in the nonproliferative DR eyes and 147.9 DA for eyes with proliferative changes. No difference was found in the median area of posterior nonperfusion between proliferative and nonproliferative eyes. For peripheral nonperfusion, nonproliferative eyes measured 64.1 DA and proliferative eyes measured 130.6 DA.  Eyes with neovascularization of the optic disc had the largest total area of retinal nonperfusion, with a difference of 65.1 DA compared with eyes with neovascularization only elsewhere.

Researchers suggest 118.3 DA as a possible threshold with a good specificity for the identification of proliferative changes. They also note that eyes with at least 107.3 DA of retinal nonperfusion are at risk for proliferative disease. The study concludes that identifying a threshold for the development of neovascularization is essential in eyes undergoing treatment because cessation of treatment in eyes with more than 100 DA of retinal nonperfusion require close observation.

Nicholson L, Ramu J, Chan EW, et al. Retinal nonperfusion characteristics on ultra-widefield angiography in eyes with severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy. JAMA Ophthalmol. April 11, 2019. [Epub ahead of print].