Proliferative diabetic retinopathy (PDR) is characterized by neovascularization of the retina, but the authors of a recent study published in Retina say we know very little about the morphological features and clinical significance of neovascularization in PDR. Their study aimed to fill this gap for three types of neovascularization elsewhere (NVE) in PDR.

The researchers classified 127 cases of NVE based on origins and morphologic features, as seen on fluorescein angiography, structural OCT and OCT-A. They compared topographical distributions, vitreoretinal interface and responsiveness to panretinal photocoagulation (PRP) in each NVE type.

Almost all cases of NVE were found at the posterior retina, with more than 96% of NVE within 6DD from the disk margin. The team reported that type 1 NVE was concentrated along or adjacent to vascular arcades. The second type had a more peripheral distribution than types 1 and 3. Additionally, an arched, bridge-like vitreoretinal interface comprised 79% of type 1 NVE, while a flat and flat-forward vitreoretinal interface made up 95% and 100% of types 2 and 3 cases, respectively. The researchers noted that after three months of PRP, regression rates were 82%, 100% and 80% for types 1, 2 and 3, respectively. They found that type 2 NVE had the greatest regression rate after PRP.

They concluded that the three types of NVE in PDR determine distinct topographical distributions, vitreoretinal interface features and differential responsiveness to PRP. “This new concept may have important clinical implications in assessing the treatment and prognosis of PDR,” they wrote.

“Various types of NVE differ in terms of responsiveness to PRP treatment,” they continued. “The efficacy of PRP in PDR may be attributed to improved inner retinal oxygen delivery, with consequent decreased angiogenic drive and regression of neovascularization.”