If an ounce of prevention is worth a pound of cure, ophthalmologists may long for the ability to turn back time to save vision. The typical patient population that most ophthalmologists see is usually comprised of patients over 50 years of age, which means we see a lot of conditions related to chronic disease and aging in the eye.
One of the most common conditions is dry (i.e., non-exudative) age-related macular degeneration (AMD). It has an estimated prevalence of 0.44% of the global population and will affect 288 million worldwide by 2040.1,2 Conditions like AMD, dry eye, glaucoma, cataracts, and diabetic retinopathy are frequently associated with chronic disease and aging.
Here, we will assess lifestyle medicine and outline what we can tell younger patients in anticipation of future vision-threatening eye conditions.
What is lifestyle medicine?
Lifestyle medicine is a field that uses evidence-based, lifestyle-focused, therapeutic interventions to prevent, treat, and, at times, reverse chronic disease.
It is founded on traditional medicine but focuses on six pillars:
- A whole-food, predominantly plant-based diet
- Increased physical activity
- Restful sleep
- Stress management
- Positive social connection
- Avoidance of risky substance use, such as alcohol and tobacco
Lifestyle medicine is delivered by clinicians trained in this specialty. These practitioners are trained to deliver prescriptive and evidenced-based lifestyle interventions to treat their patient's diabetes, hypertension, obesity, and cardiovascular disease.
In some cases, intensively applying these principles can reverse chronic disease and prevent future chronic conditions. For example, a young patient with type 2 diabetes and obesity may be advised to start a whole-food, plant-based diet as it can improve glycemic control and cardiovascular risk factors.3,4
A study of type 2 diabetic patients prescribed a low-fat vegan diet for 22 weeks, and these results were compared to patients who used the American Diabetes Association (ADA) diet, a non-plant-based diet. Of the patients who switched to a low-fat vegan diet, 43% lowered their glycemic index (versus the 26% of the ADA group), HbA1c (or A1C) decreased by 0.96 percentage points (versus 0.56 points in the ADA group), and body weight decreased by 6.5kg (3.1kg in the ADA group).
Additionally, LDL cholesterol fell 21.2% in the vegan group (10.7% in the ADA group). A plant-based diet significantly lowered risk factors for future cardiovascular events in diabetics compared to a non-plant-based diet.3 As physicians, we typically need to receive adequate education in medical school on these pillars of lifestyle medicine, especially nutrition. Empowering our patients to treat their disease's root cause is essential.
The pathophysiology behind most vision-threatening conditions, chronic disease, and aging typically stem from inflammation and oxidative stress. To protect and improve our patient's vision, we must have conversations about diet, nutrition, exercise, and sleep, as these can all affect our ocular level of inflammation and oxidative stress, specifically in our retina.
Lifestyle medicine pearls for ocular health
Nutrition
Focusing on a whole-food, plant-based diet can offer the support needed to protect the macula and reduce the risk of chronic diseases, such as diabetes, cardiovascular disease, obesity, and cancer.5 The macula is protected by carotenoids, which are macular pigments called lutein and zeaxanthin. Drusen, the hallmark of AMD, forms in the macula because of oxidative protein modifications.2
Since humans do not produce protective pigments, like lutein and zeaxanthin, getting a good dose of these pigments in our diet is important to support against oxidative protein modification and vision loss. A study revealed that dietary supplementation of lutein in humans increased serum lutein concentration and retinal lutein level as measured by macular pigment optical density (MPOD). This change was sustained for 50 days to 3 months post-supplementation.6
Furthermore, an extensive systemic review on diet and AMD showed that high glycemic index diets and alcohol consumption of greater than two drinks per day increased the association with AMD. High consumption of vegetables rich in carotenoids benefited those at risk of AMD.7 You can find carotenoids in high concentrations in fruits and vegetables like green leafy kale, spinach, and broccoli.
Omega-3s, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are long-chain omega-3 polyunsaturated fatty acids and are important for reducing reactive oxygen species in the retina. EPA and DHA are abundant in fish, shellfish, and some algae. A recent study in 2021 showed that eating fatty fish twice a week, like salmon, tuna, sardine, and mackerel, decreased the likelihood of developing diabetic retinopathy in patients with type 2 diabetes.8
Takeaways for our patients:
- Aim to get five servings of fruits and vegetables daily. Focus on getting green leafy vegetables, such as kale, broccoli, and spinach.
- Incorporate fatty fish into your diet twice a week.
Exercise
The American College of Lifestyle Medicine recommends at least 30 minutes of moderate-intensity activity 5 days a week, or 75 to 150 minutes a week of vigorous-intensity activity, to reduce inflammation. Physical activity may contribute to a denser macular pigment directly due to the reduction of inflammation and oxidative stress or indirectly by reducing obesity. Obesity is related to a lower macular pigment density.9
Physical activity in patients causes lower odds of both early and late AMD. Even a little goes a long way. A study showed that as little as 3 hours a week of moderate- to low-intensity activity was protective against AMD.2 The benefits of physical activity may extend to wet AMD as well.
Moreover, a study with mice further stressed this point. Researchers studied physical activity in two groups of mice, one group had access to an exercise wheel, while the other did not. The mice could voluntarily exercise, and after 1 month, the researchers treated the mice's eyes with lasers to simulate the changes in humans with age-related vision loss from neovascular AMD. After this treatment, the physically active mice had up to 45% less retinal damage than the nonactive mice.10
From these studies, we can gather that higher physical activity benefits our retinal health by preventing chronic age-related eye disease.
Takeaways for our patients:
- Try to get at least 30 minutes of brisk walking daily.
- Add two sessions of lifting weights per week.
Smoking cessation
Avoiding risky substances (such as tobacco) is a huge determinant for our patient's health, the risk of chronic vascular disease, and the risk of developing macular degeneration. A study showed that current smokers had a 6.6-fold increased risk of neovascular AMD versus those who had never smoked (95% confidence intervals).11 Current smokers also developed nuclear cataracts slightly younger than non-smokers (mean age 65.2 versus 67.5 years, p = 0.049).12
It is crucial to address smoking behaviors with our patients as it directly affects their visual health. Studies have also shown that more folks are ready to quit smoking. There are currently more former smokers than current smokers worldwide.13 The key to quitting is accountability and setting a quit date. As ophthalmologists, we see our patients sometimes more frequently than their primary care doctors, so it makes sense to ask them about their readiness and willingness to quit smoking.
For example, consider asking, "How do you think your smoking habits affect your vision?" or "How ready are you to quit smoking?" Setting a quit date is the most effective way to start planning smoking cessation with our patients.
Takeaways for our patients:
- Smoking cessation is important to discuss at every patient visit.
- Consider helping patients choose a quit date and keep them accountable at their next visit.
Sleep
Sleep has several important restorative functions for our brain and ocular health. Sleep helps to reorganize your brain for the next day and perform many metabolic and physiologic functions to repair and restore well-being. Excessive and reduced sleep duration increases the risk of heart disease, diabetes, and hypertension.
Perez-Canales investigated the relationship between self-reported sleep duration and AMD. They found that those with short and long sleep duration (less than 6 hours or greater than 8 hours) had an increased risk of AMD.2 We can conclude that better quality sleep improves our visual health.
Takeaways for our patients:
- Aim for 7 to 8 hours of sleep a night.
Tips for motivational interviewing
Patients can start protecting their vision by creating consistent health habits through nutrition, exercise, and sleep. Many ocular conditions are related to age and chronic disease. Consider tapping into the root cause of your patients’ conditions through the careful history of their diet, nutrition, exercise habits, smoking habits, and sleep.
When counseling patients before the end of a visit, ask them about their lifestyle habits. Explore using open-ended inquiries of areas that could be improved in their lifestyle.
Assess their readiness for change by asking: "On a scale of 0 to 10, with 10 being ready to start to make a change on XYZ today, how ready are you to change XYZ?" If their answer is a 1, ask them, "Why isn't it a 0?" and you will be able to elicit their self-motivation for possible lifestyle changes. If the response is a 5, ask, "Why is it not closer to an 8 or 9?"
Conclusion
Remember the pearls listed above, and you will empower your patients to make healthy lifestyle choices for their eyes and overall health and wellness.
