COMMENTARY

An Eye to Health: Diet and Age-Related Macular Degeneration

William C. Ou, BS; Charles C. Wykoff, MD, PhD

Disclosures

June 27, 2017

Age-related macular degeneration (AMD) is a leading cause of vision loss in the developed world, with advanced AMD affecting approximately 2 million people in the United States.[1,2] AMD is characterized by damage to the macula, the part of the retina responsible for central vision. In the advanced neovascular (or wet) form of AMD, abnormal blood vessels grow under and into the retina and can lead to severe loss of central vision due to secondary tissue disruption, exudation, and fibrosis.[1,3]

Although timely treatment with antiangiogenic agents given by intravitreal injection can minimize vision loss due to wet AMD, and indeed restore visual function in many cases,[4,5] currently there is no cure. Accordingly, there is a need to identify modifiable risk factors that can affect the development of AMD and its progression to advanced stages. For example, cigarette smoking[6] and obesity[7,8] have both been demonstrated to have a significant impact on AMD development and progression.

Does Diet Affect the Risk for AMD?

Substantial research, particularly within the past three decades, has been devoted to dietary and nutritional factors that may influence AMD development or progression.[9]

The retina appears to be highly susceptible to oxidative stress; such oxidative damage may play a role in AMD pathogenesis,[10] and therefore compounds that counteract oxidative damage may protect against both development and progression of AMD.[11,12,13,14]

The Age-Related Eye Disease Study (AREDS) found that a specific formulation of antioxidants and minerals, including vitamin C, vitamin E, beta-carotene, zinc, and copper, reduced the risk of patients with intermediate AMD developing the advanced form of the condition by 25% over 5 years.[12] Subsequently, the follow-up AREDS 2 study found that lutein and zeaxanthin can be substituted for beta-carotene, which has been linked to increased risk for lung cancer, particularly among former smokers.[13,15]

Beyond high-dose supplementation, intake of antioxidants and omega-3 long-chain polyunsaturated fatty acids through daily diet has also been reported to reduce AMD risk.[11,14,16]

Such findings have led many clinicians to recommend consumption of foods rich in these nutrients, including green, leafy vegetables (eg, spinach), fish, and whole grains (eg, brown rice).[1,11,14]

Similarly, epidemiologic studies have reported that a high glycemic index (GI) diet is a risk factor for AMD.[9,17] The GI represents a food's impact on blood glucose levels relative to pure glucose (GI = 100). Consumption of higher-GI foods results in higher blood glucose levels. High GI foods (GI > 70) include white rice, white bread, and potatoes, whereas whole grains, lentils, and nonstarchy vegetables such as broccoli and cabbage have a low GI (GI < 55). High-GI diets are associated with accumulation of advanced glycation end-products (AGEs) that are formed when cellular proteins are modified by sugar molecules or their metabolites.[18] It has been suggested that AGEs may contribute to AMD pathogenesis at the molecular level by causing dysfunction of cellular protein editing and degradation in the outer retina and choroidal tissues.[9,18]

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