Proanthocyanidins, a class of polyphenolic compounds found in various plants (notably grape seeds and pine bark), have been investigated for their potential benefits in diabetic retinopathy (DR). Their use is supported by some scientific research, although evidence remains limited and largely preclinical or based on small trials. The rationale for proanthocyanidins in DR centers on their antioxidant, anti-inflammatory, and vascular-protective properties. Oxidative stress and microvascular damage are central to the pathogenesis of diabetic retinopathy, and proanthocyanidins are believed to scavenge free radicals, inhibit lipid peroxidation, and strengthen capillary walls.

Several animal studies have demonstrated that proanthocyanidins can reduce retinal oxidative stress, decrease vascular leakage, and inhibit the progression of retinal damage in diabetic models. Some small human studies and clinical trials, particularly with grape seed extract or Pycnogenol (a standardized pine bark proanthocyanidin extract), suggest possible improvements in retinal blood flow and reductions in retinal edema or microaneurysm formation. However, these studies are generally of low to moderate quality, with small sample sizes, short durations, and methodological limitations.

Current clinical guidelines do not recommend proanthocyanidins as a primary treatment for diabetic retinopathy, but they may be considered as adjunctive supportive agents. Overall, while there is some scientific basis for their use, the evidence is not robust, and further high-quality research is needed.