Working to Prevent Age-Related Macular Degeneration
By Leo Semes, OD, FAAO
Dr. Regina Benjamin, U.S. Surgeon General, recently released a report titled "The Surgeon General's Vision for a Healthy and Fit Nation" (2010). In it she calls for a war against obesity, citing significant negative health outcomes. Among these are high blood pressure, high cholesterol, type 2 diabetes and its complications, coronary heart disease, and stroke, among others.
Recognizing the parallels between heart disease and age-related macular degeneration (AMD), we as eyecare professionals can fight the battle to preserve our aging patients' sight and vision. We can consider two premises: AMD is a potentially serious public health problem, and interventions may alter it favorably. What should eyecare professionals' role in AMD prevention, or at least amelioration, be?
Discuss Modifiable Behaviors
First, eyecare professionals can discuss lifestyle choices such as smoking cessation and dietary modifications with at-risk patients. The discussion about the negative health effects of smoking may seem awkward. The fact that cancer and loss of vision represent two of the most significant fears of older adults may serve as a good starting point. Evidence is undeniable concerning the association between cigarette smoking and AMD (Chu et al, 2008; Francis et al, 2007).
Beyond some general guidelines and new information from one preliminary study, we can rely on the results of the AREDS and AREDS2 studies. In addition, we can offer guided preventive measures such as sunlight protection, which I will discuss in another column. Let's look at the AREDS studies.
Learn From the AREDS Studies
The first AREDS study was conducted over a five-year period and, to be brief, demonstrated that patients with more advanced cases of AMD (all "dry") benefited from oral administration of antioxidant vitamins (C, E, and beta-carotene) plus zinc/copper. Other study medications included the antioxidant trio, zinc/copper, and placebo. A useful resource is the NEI summary of the study (www.nei.nih.gov/amd/summary.asp). The Web site includes Frequently Asked Questions that may be valuable to patients.
AREDS guidance suggested the study formulation for those at highest risk of suffering vision loss from AMD. A simplified fiveyear risk tabulation is available (Ferris et al, 2005). Essentially, patients who have large drusen and pigment disturbances within the macula are at highest risk.
AREDS2 has completed recruitment, and the results will be available in 2014. The purpose is to evaluate the effect of the two dietary xanthophylls (lutein and zeaxanthin), which have been shown to accumulate in the macula when administered orally, and the effect of two omega-3 longchain polyunsaturated fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), on progression to advanced AMD and/or moderate vision loss in people at moderate-to-high risk for progression. Patients will be randomized to one of three interventions (lutein/zeaxanthin [L/Z], omega-3, and both L/Z and omega-3) plus a placebo group.
In both of these studies, the minimum age for inclusion was 50 years. So, for our over-50 patients at high risk, what is the best guidance? Based on AREDS, that would be the combination of high doses of antioxidant vitamins and zinc. Based on one preliminary report from AREDS2, it appears that omega-3 intake reduces the risk of progression from bilateral drusen to central geographic atrophy (SanGiovanni et al, 2008). Stay tuned. CLS
For references, please visit www.clspectrum.com/references.asp and click on document #178.
Dr. Semes is a professor of optometry at the UAB School of Optometry.