Antioxidants in the prevention and treatment of diabetic retinopathy – a review

Diabetic retinopathy is a disease resulting from diabetic chronic hyperglycemia characterized by microvascular complications in the retina, where neuronal elements responsible for vision are located. It is the main cause of adult blindness in developed countries. Oxidative stress has been widely regarded as the key factor for the emergence of ocular disease and has been involved in increased vascular permeability, disruption of blood-retinal barrier, apoptotic loss of retinal capillary cells, microvascular abnormalities and retinal neovascularization. Dietary supplementation with antioxidants has been related with inhibition of diabetes-induced abnormalities of retinal metabolism, reduction of apoptosis and partial restoration of pericytes. Moreover, the use of topical antioxidants to treat or delaying oxidative stress-related ocular manifestations is still poorly explored, while current diabetic retinopathy therapy includes invasive methods, like surgery. Ocular antioxidant potential therapy represents a non-invasive, safe and less painful methodology, which slows the natural progress of the disease and improves the effectiveness of treatment without significant systemic toxicity. This review underlines the innovative medicines exploited for ocular conditions, a further insight on ocular delivery, benefiting from the advantages of the eye for drug delivery and, additionally, offering new potential applications of antioxidants for the prevention, treatment and control of diabetic retinopathy.