Managing Diabetic Eye Disease One Meal at a Time

As eye care professionals, we are acutely aware of how systemic conditions, such as diabetes, affect the visual system. Diabetic macular oedema is a common complication requiring intravitreal treatment, and diabetic retinopathy continues to pose a significant threat to vision. Regular eye examinations and blood sugar control remain the pillars of prevention.

However, increasing evidence points to the pivotal role of nutrition in reducing risk and preserving sight. In clinical practice, patients often overlook how dietary choices directly affect their vision. Introducing these insights during eye exams, particularly for those with systemic conditions like diabetes, can increase patient engagement in preventive care. As we see growing global trends in both pre-diabetes and metabolic syndrome, the importance of early lifestyle interventions becomes increasingly important.

According to the International Diabetes Federation, approximately 415 million adults were living with diabetes worldwide in 2015,¹ with 90% of cases classified as type 2 diabetes. Modern lifestyles – including such things as sedentary behaviour, high glycaemic diets, and obesity – have significantly contributed to this rise.

Having dipped a toe into nutrition education during my career in orthoptics, it became so obvious how our nutritional choices, physical activity, and daily habits directly impact eye health. Understanding the roles of oxidative stress, glycaemic load, and omega 3 fatty acids empowers both practitioners and patients to approach diabetes management holistically.

Nutrition should no longer be seen as a peripheral concern, but rather a central factor in the preservation of vision

Hyperglycaemia and Oxidative Stress

Hyperglycaemia, or elevated blood glucose levels, can be influenced by both diet and physical activity. Uncontrolled hyperglycaemia not only worsens systemic outcomes such as coronary heart disease, nephropathy, and neuropathy, but also accelerates ocular complications like retinopathy.

Sustained hyperglycaemia has been identified as a major contributor to diabetic retinopathy, primarily through oxidative stress pathways. This stress leads to cellular damage and contributes to retinal capillary apoptosis. In diabetic patients, retinal cells are particularly vulnerable to damage from elevated blood sugar levels. When oxidative stress surpasses the body’s ability to neutralise free radicals, it leads to cellular dysfunction and apoptosis. This has been observed not only in retinopathy, but also in age-related macular degeneration (AMD)2 and glaucoma.³

A review of antioxidant therapies in diabetic retinopathy has shown that degeneration of retinal capillaries can be reduced with antioxidant treatment, indicating that oxidative stress plays a critical pathological role.⁴

A study conducted at Flinders University further supports this, suggesting that antioxidant strategies may be effective in early stages of disease but this requires further clinical validation.⁵

Beyond the eyes, antioxidant-rich diets may also benefit systemic conditions like neurodegenerative disease.6 That said, caution must be taken to avoid overuse, as excess antioxidants can lead to unintended cellular effects. More research is required into the potential side effects of overuse of antioxidants.

As discussed in Diabetes Australia resources, antioxidants like vitamins C and E are found in spinach, eggs, avocado, carrots, broccoli, and capsicums. These are easily incorporated into daily meals and can help to reduce the risk of debilitating visual changes.

Glycaemic Load and Vision Preservation

Glycaemic control is central to diabetes management. From a nutritional standpoint, several approaches – such as the Mediterranean diet, the DASH (dietary approaches to stop hypertension) diet, the Nordic diet, and low-carbohydrate or high-fibre regimens – can support more stable blood glucose levels. However, all interventions must be tailored to the individual, ideally with guidance from a dietitian or clinical nutrition professional to find the most effective fit.

In a systematic review from the European Journal of Epidemiology,⁷ the studies involved showed that adherence to the Mediterranean diet and high fruit, vegetables, and fish intake might help to protect against diabetic retinopathy, although there is still much research needed in this area.

Incorporating low-glycaemic index foods, such as legumes and whole grains, can help minimise postprandial glucose spikes and reduce retinal stress.

Omega 3 Fatty Acids and Retinal Health

Omega 3 fatty acids – particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) – are essential fats that cannot be synthesised by the body and must be obtained through diet. These are commonly found in fish such as mackerel, trout, anchovies, sardines, tuna, and salmon, as well as in shellfish and seaweed.

Omega 3s offer wide-ranging health benefits: they are anti-inflammatory, anti-thrombotic, and cardioprotective,^8-12 and they also show promise in the treatment of mood disorders and hypertension.

Specifically regarding eye health, a study published in JAMA Ophthalmology reported that higher dietary intake of omega 3s was significantly associated with a lower risk of sight-threatening diabetic retinopathy in individuals with type 2 diabetes.¹³

Conclusion

As eye care professionals, we are in a powerful position to support a multidisciplinary approach to diabetic eye disease and other eye conditions. Incorporating basic nutritional education within our scope of practice allows us to empower patients, slow disease progression, and preserve vision. With the right strategies and dietary habits, we can help our patients protect their sight – one meal at a time. Future collaborative care models involving ophthalmologists, optometrists, general practitioners, clinical nutritionists, and accredited dietitians could enhance preventive outcomes. By equipping patients with both clinical treatment and accessible lifestyle and nutritional guidance, we reinforce a comprehensive strategy for managing many eye conditions, not just limited to diabetes-related conditions.

Nutrition should no longer be seen as a peripheral concern, but rather a central factor in the preservation of vision. As eye health professionals, we should look to focus on empowering patients through education, bridging the gap between traditional clinical care and modern lifestyle medicine.

Peggie Moynihan BSc Orthoptics MN Nutr has worked in the public and private sectors in Ireland and Australia. With a background in clinical eye care and evidence-based nutrition, she has a strong interest in the impact nutrition has on eye health.

References

1. International Centre for Eye Health. Diabetes and eye health. Community Eye Health Journal. 2015;28(92):57-58.
2. Ruan Y, Jiang S, Gericke A. Age-related macular degeneration: Role of oxidative stress and blood vessels. Int J Mol Sci. 2021 Jan 28;22(3):1296. doi: 10.3390/ijms22031296.
3. Tezel G. Oxidative stress in glaucomatous neurodegeneration: mechanisms and consequences. Prog Retin Eye Res. 2006 Sep;25(5):490-513. doi: 10.1016/j.preteyeres.2006.07.003.
4. Li C, Miao X, Sun J, et al. Oxidative stress-related mechanisms and antioxidant therapy in diabetic retinopathy. Oxid Med Cell Longev. 2017;2017:9702820. doi: 10.1155/2017/9702820.
5. Haydinger CD, Oliver GF, Ashander LM, Smith JR. Oxidative stress and its regulation in diabetic retinopathy. Int J Mol Sci. 2023;24(1):123. doi: 10.3390/ijms24010123.
6. Fatima MT, Bhat AA, Akil ASA, et al. The role of dietary antioxidants in type 2 diabetes and neurodegenerative disorders: An assessment of the benefit profile. Front Neurosci. 2022;16:893415. doi: 10.3389/fnins.2022.893415.
7. Dow C, Mancini F, Fagherazzi G, et al. Diet and risk of diabetic retinopathy: a systematic review. Eur J Epidemiol. 2018;33(2)141-156 (2018). doi: 10.1007/s10654-017-0338-8.
8. Eslick GD, Howe PRC, Bensoussan A, et al. Benefits of fish oil supplementation in hyperlipidemia: a systematic review and meta-analysis. Am J Clin Nutr. 2009;90(5):1075–84. doi: 10.3945/ajcn.2009.27469.
9. Calder PC. Marine omega-3 fatty acids and inflammatory processes: Effects, mechanisms and clinical relevance. Biochim Biophys Acta. 2015;1851(4):469-84. doi: 10.1016/j.bbalip.2014.08.010.
10. Gao LG, Cao J, Mao QX, Lu XC, Zhou X. Influence of omega-3 polyunsaturated fatty acid supplementation on platelet aggregation in humans: a meta-analysis of randomized controlled trials. Atherosclerosis. 2013;226(2):328-34. doi: 10.1016/j.atherosclerosis.2012.10.062.
11. Liao Y, Xie B, Zhang H, McIntyre RS, et al. Efficacy of omega-3 polyunsaturated fatty acids in depression: a meta-analysis. Transl Psychiatry. 2019;9(1):190. doi: 10.1038/s41398-019-0515-5.
12. Miller PE, Van Elswyk M, Alexander DD. Long-chain omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid and blood pressure: a meta-analysis of randomized controlled trials. Am J Hypertens. 2014;27(7):885-96. doi: 10.1093/ajh/hpt294.
13. Sala-Vila A, Díaz-López A, Valls-Pedret C, et al. Dietary marine omega-3 fatty acids and incident sight-threatening retinopathy in middle-aged and older individuals with type 2 diabetes: A prospective cohort study. JAMA Ophthalmol. 2016;134(10):1142–9. doi: 10.1001/jamaophthalmol.2016.2901.