Procyanidol (also known as procyanidolic oligomers or proanthocyanidins) is a class of polyphenolic compounds found in a variety of plants, including grape seeds and pine bark. There is some scientific evidence supporting the use of procyanidins in the management of diabetic retinopathy, although the quality and quantity of data are limited. The rationale for use is based on their strong antioxidant properties, which may help protect retinal blood vessels from oxidative stress and microvascular damage commonly seen in diabetic retinopathy. Experimental studies have shown that procyanidins can reduce capillary fragility and permeability, which are key factors in the development and progression of diabetic retinopathy.

Clinical studies are limited and often small in scale, but some trials suggest that supplementation with procyanidolic oligomers (such as those from Vitis vinifera or Pinus pinaster) may improve retinal microcirculation and reduce the severity or progression of early-stage diabetic retinopathy. A few studies have reported improvements in retinal hemorrhages and microaneurysms with use. However, systematic reviews and large-scale, high-quality randomized clinical trials are lacking, and major diabetes or ophthalmology guidelines do not currently recommend procyanidins as standard therapy for diabetic retinopathy. The evidence base is thus preliminary and warrants further investigation.