May is national “Healthy Vision Month,” so we spoke with Emily Chew, M.D. from the National Eye Institute (NEI) to learn more about visual impairment and what we can do to prevent it. As deputy clinical director, Chew works one-on-one with patients and conducts research in diabetic eye disease and age-related eye diseases, among other ocular diseases.
Approximately 2/3 of the blind and visually-impaired population worldwide are women. Are females more susceptible to visual impairment than males?
No, although there are a few conditions that may have a higher rate in females, such as Fuch’s corneal dystrophy. The overall increased number of visual impairment in women may be due to the longevity of women compared with men, as a large number of eye diseases are age-related.
Your division at NEI has been studying the effects of dietary supplements (e.g. omega-3 fatty acids, vitamin E, beta-carotene, zinc) as an aid to combatting age-related vision loss. Have certain supplements proven to be effective?
In 2001, we announced the results of the Age-Related Eye Disease Study (AREDS), which demonstrated that the combination of vitamins C, E, and beta-carotene plus zinc with copper, known as the AREDS supplement, reduced the risk of developing late age-related macular degeneration (AMD) and vision loss in people with at least intermediate AMD.
In 2006, a new study was launched—the Age-Related Eye Disease Study 2 (AREDS2)—to test whether adding lutein plus zeaxanthin or omega-3 fatty acids to the AREDS supplement would provide additional benefits. Omega-3 fatty acids were not found to be beneficial or harmful. Replacing beta-carotene with lutein and zeaxanthin improved the benefits of the supplement in reducing the risk of late AMD development and reduced the risk of lung cancer in former smokers. The AREDS2 supplement would thus be safer and provide additional benefit for people with intermediate AMD in both eyes or late AMD in one eye.
According to Women’s Eye Health (WEH), more than ¾ of visual impairment is estimated to be preventable or correctable. What are some other methods of prevention/correction?
The largest cause of visual impairment has been uncorrected refractive errors (like near-sightedness and astigmatism), which can be easily corrected with refraction and glasses. Others include cataract formation, which can be improved with surgery. Diabetic retinopathy is another important disease that needs to be monitored with yearly dilated eye exams; catching it early ensures we can administer its highly effective therapy.
In addition, we need to emphasize to patients how controlling their blood glucose and blood pressure can help reduce the progression rate of diabetic retinopathy. Managing dyslipidemia, or high cholesterol, especially with an agent such as fenofibrate would also be important also for reducing diabetic retinopathy progression. Taking the AREDS/AREDS2 supplements would also reduce the visual burden from AMD. Early monitoring of eyes at risk for developing late AMD would help reduce the risk of vision loss.
Finally, it is important to stress that everyone needs to have a good diet—eating fish at least twice per week as well as several helpings of vegetables, especially green leafy vegetables—to maintain their eye health.
The number of people affected by age-related macular degeneration (AMD) is expected to increase by more than 50% by 2020. Are there hopes of finding a cure by that time?
I have no crystal ball, but a number of trials are ongoing. Hopefully, we will work towards a beneficial therapy for dry AMD or eventually a therapy that is a primary prevention for AMD. Further refinements of the anti-VEGF therapies and potential adjunct therapies may result in further reduction in vision loss from wet AMD as well as reduction in treatment burden.
What are some recent advances in vision research?
The biggest advance is the development of anti-VEGF therapies for the treatment of AMD. Others include the development of the optical coherence tomography (OCT) which allows the physician to detect very minute and clinically important changes in the retina. Such images from the OCT have resulted in better diagnostic tools as well as providing guidance for on-going therapy. These two developments have revolutionized how we can provide care for people with AMD, diabetic retinopathy, and other retinal diseases.
There’s more than one way to be proactive about Healthy Vision Month! Aside from spreading the word to family and friends, the National Eye Institute suggests these steps to keep your eyes in check. As Chew recommends, retaining a strong diet is key for maintaining eye health. The American Macular Degeneration Foundation published a chart with fruits and vegetables high in lutein and zeaxanthin–some examples being spinach, eggs, broccoli, and oranges. For more information on healthy vision for all ages, click here.