Omega-3 Polyunsaturated Fatty Acids and Their Anti-Oxidant, Anti-Inflammatory and Neuroprotective Effects in Diabetic Retinopathy: A Narrative Review.

Diabetic retinopathy (DR) is a common microvascular complication of type 2 Diabetes Mellitus (T2DM) that can have vision-threatening consequences, particularly if it advances to the proliferative stage and is left untreated. Owing to the central role of hyperglycemia-induced oxidative stress, multiple anti-oxidants have been investigated for their therapeutic value. However, there is a lack of substantial data to support the use of any of the compounds tested so far. Omega-3 polyunsaturated fatty acids (PUFAs), namely docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have received much acclaim for their positive impact on cardiovascular health outcomes. The anti-oxidative, anti-inflammatory and neuroprotective properties of PUFAs also make them promising therapeutic and preventive agents for DR. The current evidence is derived mainly from and animal studies and provides some insight into the underlying mechanisms involved. These fatty acids are capable of direct anti-oxidative and anti-inflammatory effects. They also concomitantly promote intrinsic defense mechanisms and recovery, particularly of photoreceptor neurons. Hence, dietary supplementation with PUFAs, mainly from marine sources, can halt and reverse the retinal damage seen in DR. Furthermore, clinical trials have reported improved vision and quality of life in DR patients after supplementation. However, a major limitation of these trials is the use of nutraceutical formulations in which omega-3 PUFAs are combined with other anti-oxidant compounds, thereby preventing the evaluation of omega-3 as standalone treatment. Although the results of experimental studies to date have been promising, more clinical trials are required to determine the full extent of benefits in patients with DR.