We, as eye care providers, know that approaching key lifestyle factors, like diet, can have long-term effects on a patient’s ocular health. So, helping patients bridge the gap between their nutrition and health, specifically when it impacts vision, is an important facet of the care that we can provide.

Below, we will review the nutrients that can best help with retina health and how to discuss proper nutrition with patients.

Nutrients

It is important to note that it is difficult to quantify a single nutrient in the prevention of eye disease. It is more likely that nutrients are acting synergistically to provide protection. In addition, recommending a single nutrient alone without considering factors such as absorption rates, toxicity doses, or high-risk individuals (as is in the case of beta-carotene and smokers), could negate the very benefits of a nutrient for eye health. For this reason, it may be prudent to recommend food choices rich in the below-mentioned nutrients when discussing nutrition and eye health with patients.¹

The nutrients that can assist patients with retina health, along with what foods contain those nutrients, include:

• Anthocyanins. These are strong antioxidants of red-purple pigments found in plants; they support anti-inflammatory properties in the eye, which can help prevent or reduce the risk associated with age-related macular degeneration (AMD). Berries, such as blueberry, bilberry, blackcurrant, strawberry, and wolfberry (better known as “goji berry”), are rich in anthocyanins.²
• Beta-carotene. This is a carotenoid (a type of antioxidant found in the pigments of some plants) that was determined to reduce the risk of developing advanced AMD.³ Beta-carotene, which is heavily associated with vitamin A, is rich in sweet potatoes, pumpkins, apricots, and carrots.¹ Note: A high intake of beta-carotene (20 mg per day) has been associated with an increased chance of lung cancer in current or former smokers, or people with history of asbestos exposure.¹ Be sure to check with patients to see if they fall into those categories before recommending beta-carotene.
• Lutein, zeaxanthin, and meso-zeaxanthin. These antioxidant carotenoids act as natural filters of light, and they are optimal performers in visual function. They perform these roles by absorbing incoming blue light, which helps to protect against oxidative damage and also inhibits aberration, which aids in visual performance.^4-8 Interestingly enough, visual performance, including contrast sensitivity, glare tolerance, and photo stress recovery are shown to improve with lutein, zeaxanthin, and meso-zeaxanthin supplementation.^5,9,10 The foods that have lutein and zeaxanthin content are green, leafy vegetables and fruits, such as kale, avocado, and corn. Meso-zeaxanthin is converted from lutein in the macula, although individuals with AMD might have limitations in this biosynthesis of meso-zeaxanthin.¹¹
• Omega-3 fatty acids. These include docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which act to orchestrate varying changes at different levels within the retina. The effects of Omega-3s include signaling anti-inflammatory efforts, redirecting pathological angiogenesis (which means the growth of new blood vessels, usually from vessel loss induced by hypoxia), protecting against retinal degeneration (such as neurotoxicity), and helping regenerate photoreceptors.¹² Fish rich in EPA and DHA include herring, salmon, white canned tuna, and sardines.³
• Vitamin A. As stated above, vitamin A is closely tied to beta-carotenoids, as that nutrient converts to vitamin A in the body. A normal level of vitamin A is essential for good vision, since vitamin A helps with a process of biochemical reactions that regenerate visual pigment following exposure to light.¹³ Too much vitamin A or too little can be harmful. Several disease states caused by too little vitamin A or too much are connected with vitamin A pathways in the retina.¹³ Food sources of vitamin A include dairy products, eggs, fish, meat (especially liver), and fruits and plants rich in beta-carotene.¹³
• Vitamins C and E. These antioxidants reduce the cellular oxidative stress on the retina and macula, and can reduce the risk of developing advanced AMD.¹ The role of vitamin C and E in diabetes includes reducing ocular inflammation and preventing diabetic-related microvascular complications, such as diabetic retinopathy, nephropathy, and neuropathy.^1,14 Sources of vitamin C include oranges, blackberries, blueberries, raw produce such as spinach, broccoli, green peppers, tomatoes, and grapefruit, and cooked brussels sprouts and turnips;¹ sources of vitamin E include sunflower seeds, almonds, peanuts, and peanut butter.¹
• Zinc. This is a potent antioxidant in the pathogenesis of diabetic retinopathy and AMD.¹⁵ Zinc deficiency, which is more common in the elderly, can be a cause of poor dark adaptation and night blindness and often can be reversed with nutritional modifications.^15-18 Sources of zinc include oysters, meat, pumpkin seeds, and peanuts.¹

Discussing nutrition with patients

Now that we’ve reviewed the ideal nutrients and foods for retina health, how can we effectively discuss this topic with our patients and help them take a proactive role in their eye health?

For starters, here is a patient script I use when patients ask how they can protect their eyesight and/or prevent eye disease: “Paying attention to our diet is a great first step to take now, as it can lower the risk of eye problems in the future. Just like a healthy diet can decrease the risk of things like heart disease or strengthen your immunity to sickness, there is a connection between our what nutrients we eat and eye health.”

Here are a few additional ways to bridge the information gap between nutrition and retinal health:

• Ask questions. Don’t rely on the patient intake questionnaire. I always ask my diabetic patients about recent A1C results, and I also want to know how they are controlling their blood sugars, whether through diet, exercise, and/or medication. I ask my AMD patients about diet and supplements. Asking these specific questions allows me to tailor recommendations, including lifestyle modifications, to a patient’s individual needs. Specifically asking about diet also lets me see whether they’re taking any of the above nutrients I also like to ask AMD patients if they are taking any vitamins or a supplement specific to eye health. I find that most patients are aware of over-the-counter “eye vitamins,” but not aware what they really do with regards to eye heath. For patients with AMD or a strong family history of AMD, while I do discuss the benefits of a nutrient-rich diet, my conversation does center around supplementation with an eye vitamin containing many of the nutrients listed in the first section. While foods such as broccoli, pumpkin, sunflower seeds, chickpeas or salmon pack a super punch of essential nutrients recommended for daily intake, most individuals on average only get 1-2 mg of these nutrients through diet alone. This is why supplements, which can provide 10-12 mg of these nutrients, are recommended for AMD patients.
• Use analogies. Retinal health changes related to different systemic and ocular disease processes, such as macular degeneration, diabetic retinopathy, and hypertensive retinopathy, can be complicated and difficult for a patient to grasp. Simplifying complex concepts can lead to a greater understanding and retention on the patient’s behalf. A favorite of mine for AMD patients is to compare the macula to a healthy lawn: “Just like a lawn, unfavorable conditions, like excess sunlight or unhealthy soil, can cause damage over time. On a lawn, you’ll notice this when a patch of grass dies, but on the eye, you’ll notice it when you start seeing sun spots. Like a lawn, you can help preserve your eye by keeping it protected from excess sun and making sure it gets the right nutrients to grow. That’s why, for our eyes, diet is important in combating those unfavorable conditions.”
• Share visual aids. When you can easily demonstrate changes to structures in the back of the eye, the conceptual becomes more tangible to the patient. I often pull up multiple images associated with a patient’s fundus image explaining what I’m seeing or not seeing (see image on P. 40). While sharing these images with them, I take the time to emphasize how nutrients factor into so many aspects of healthy eyesight. Other, non-clinical visual aids can be helpful as well. As an example, I recently attended a lecture about diabetes and retinal health. The presenter discussed how she helped patients understand dietary sugar intake by showing pictures of food and drinks with corresponding sugar cubes stacked up nicely right beside each. This was a simple but powerful way to visually show her patients just how much sugar was in each particular item.

Get your patient’s attention

In my experience, many patients are still not aware of the importance of diet and its potential impact on retinal health, especially in disease states, like diabetes. While we as eyecare providers understand the cascade of events that lead to vision changes, our patients may not make the connection.

Educating our patients about the role of nutrition in maintaining optimal retinal health is an essential and a worthwhile effort that starts in the exam lane. With a variety of strategies, including asking thorough patient questions, simplifying concepts, and using images and photos, we can encourage sustainable lifestyle changes to include nutritional intervention. If we, as eye care providers, can educate our patients in ways that help them better grasp these disease processes and preventative strategies, they can take a more active role in their own care, and everyone wins. OM

References:

References

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3. Age-Related Eye Disease Study Research Group. A randomized, placebo-controlled, clinical trial of high-dose supplementation with vitamins C and E, beta carotene, and zinc for age-related macular degeneration and vision loss: AREDS report no 8. Arch Ophthalmol. 2001;119:1417-1436. doi: 10.1001/archopht.119.10.1417.
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10. Stringham JM, O'Brien KJ, Stringham NT. Contrast Sensitivity and Lateral Inhibition Are Enhanced With Macular Carotenoid Supplementation. Invest Ophthalmol Vis Sci. 2017 Apr 1;58(4):2291-2295. doi: 10.1167/iovs.16-21087. PMID: 28431432.
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DR. WADEMAN has been in pracitce for 15 years, and the owner of Bidwell Optometry, in Folsom, Calif., for the past 12 years. She is a graduate of the Southern California College of Optometry.