Degenerative eye diseases affect more than 13 million people in the United States, and by the year 2020, it is estimated that one-fourth of the U.S. population will be affected. One of those eye diseases, macular degeneration, is the leading cause of blindness in people over the age of 65.
Macular degeneration results in loss of central, high-resolution vision due to damage of the macula, an oval-shaped spot near the center of the retina. It can make certain activities, such as reading, more difficult. There is no cure for macular degeneration, but certain steps such as nutrition and early diagnosis can reduce risk.
Low lutein levels can indicate a risk for macular degeneration, and one way to reduce that risk is to increase lutein intake in your diet. Green leafy vegetables contain the most lutein, and the darker the green — such as kale and spinach — the better. Nearly half of Americans don’t get enough lutein, a natural antioxidant, in their diet. Experts recommend 10 mg daily, yet many people don’t get above 2 mg.
One eye exam, known as a macular pigment optical density screening, tests the levels of lutein and zeaxanthin, another nutrient, in a patient’s macula. It consists of a light response test which lasts for approximately five minutes. In the experience of Des Moines optometrist Dr. David Scott, early tracking through the screening helped 85% of patients return to safe levels of both nutrients.
He particularly recommends the screening for smokers and for those with a family history of macular degeneration, both high-risk groups. Dr. Scott rescreens patients after six months to check progress, but patients with average levels can be rescreened after five years. The average score is .38 density units, and patients should become concerned if they score below .2. For patients who score under .3, he recommends over-the-counter (OTC) eye vitamins.
Those OTC eye vitamins are referred to as the “Areds formula,” named after the “Age-Related Eye Disease Study,” conducted by the National Eye Institute at the National Institutes of Health. In the study, 3,600 patients took specific amounts of vitamin C, vitamin E, beta carotene, zinc, and copper together. The combination was found to reduce the risk of developing advanced eye disease by 25%, and also led to a 19% reduction in vision loss for those already diagnosed with macular degeneration.
Stephen Rose, chief research officer for the Foundation Fighting Blindness, advises that the Areds formula should only be taken under a doctor’s recommendation. He also advises that diet alone and standard daily multivitamins cannot provide the same high levels of antioxidants and zinc as the Areds formulation. The National Eye Institute is now conducting Areds II because of evidence that DHA, EPA, lutein, and zeaxanthin may lower macular degeneration risk.
Since the 1940s, a test called the Amsler Grid has been used to track vision distortion in patients diagnosed with degenerative eye disease. The test looks similar to graph paper with a black dot in the center. As patients focus on the dot, they can see blurred, wavy, or missing lines on the grid. A new test, developed by Dr. Yu-Guang He, associate professor of ophthalmology at University of Texas Southwestern and an ophthalmologist at the school’s Medical Center, is twice as sensitive as the Amsler Grid and gives results in under two minutes.
It comes in the form of an app, called myVisionTrack, for the iPhone or iPod Touch. “Many patients do not have timely eye exams and end up suffering preventable vision loss,” Dr. He said. “Careful self-monitoring is critical because treatment for age-related macular degeneration and diabetic retinopathy is most effective when given at precise stages in the disease’s progression.”
In an article for Eye Doc News, Dr. Risa Schulman describes how the app works:
The test uses a ‘shape discrimination’ exercise, where three circles are shown on the screen. Patients cover one eye and touch the circle they perceive to be oddly shaped. This brings up 3 more circles with more subtle differences, and so on. The exercise is then repeated with the other eye. The app stores the results each time, and if there is a significant change in vision over time, the patient gets a message to see the doctor.
The app is not currently available, but will be added to the Apple App Store in the near future.
Source: “Vitamins to Prevent Vision Loss,” Consults blog (The New York Times), 07/14/11
Source: “Quick test can reduce risk of eye issues later,” Des Moines Register, 07/26/11
Source: “iPhone App Allows Patients to Self-Monitor Progress of Macular Degeneration and Diabetic Retinopathy,” Eye Doc News, 08/04/11
Source: “UT Southwestern ophthalmologist helps develop device for monitoring degenerative eye disease,” press release from University of Texas Southwestern, 07/26/11
Image by krossbow (F Delventhal), used under its Creative Commons license.