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Modifiable risk factors, nutritional supplements key to battling dry AMD
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 Richard L. Lindstrom |
Age-related macular degeneration is the leading cause of blindness in people older than 60 years in the U.S. and other advanced countries in the world. Ten percent of the citizens of these countries between the ages of 66 years and 74 years and 30% between the ages of 75 years and 85 years manifest this sight-threatening condition.
The majority of AMD, in the range of 85%, is the dry form. The transformational introduction of treatment with intraocular anti-VEGF injections for the 15% of patients who progress to wet AMD is nothing short of amazing. Still, starting Jan. 1, the 78 million members of the baby boomer population in the U.S. began turning 65, making them eligible for Medicare and at significant risk for the development of dry AMD. Sadly, we have no such transformational therapy for this malady, and its natural history for most is one of inexorable slow progression with increasing visual loss.
It is estimated that the patient who is older than 65 years consumes 10 times the eye care compared with the patient who is younger than 65 years. Thus, the baby boomer senior population demographic can be expected to seek medical care at an ever-increasing frequency over the next 3 decades, as their hard-driving lifestyles demand quality vision. The biggest threat to their vision and lifestyle is AMD. It is important for all of us to be prepared to do all we can to prevent AMD and restore or enhance visual function when it presents.
The early findings of dry AMD, retinal pigment dispersion or atrophy, and drusen formation are easily seen during fundus examination. Patients with these findings are at risk of progression to visual loss, and they need to be aware of the other risk factors for AMD and be given the opportunity to modify their behavior to reduce their risk of developing this potentially disabling problem.
One important risk factor is a positive family history, and similar to the patient with a positive family history of glaucoma, those with a positive family history of AMD deserve more careful counseling and follow-up. Key risk factors that we cannot modify include Caucasian race, increasing age and the female gender. Thus, the highest-risk patient is the older white woman with a positive family history; more than 50% of these patients living until at least 80 years will develop some level of AMD.
Special effort should be made with these patients to mitigate modifiable risk factors. The most important of these are smoking, hypertension, obesity and an abnormal lipid profile with elevated cholesterol. While changing lifelong habits is extremely difficult, patients made aware of these risks may be motivated to make constructive change. Those with high-risk profiles can be counseled to watch for early symptoms such as metamorphopsia and taught how to monitor their central vision with an Amsler grid at home. Preferential hyperacuity perimetry, now available in the ophthalmologist’s office, is in development for home use to allow early detection of progression. This may alert patients who are developing significant progression between office visits to schedule an interim examination, reducing the chance of permanent damage.
Our primary tool in retarding the progression of dry AMD remains diet modification and nutritional supplements. Increased consumption of green leafy vegetables and foods rich in omega-3 fatty acids appears beneficial in the majority of studies worldwide. Because it is the rare American who can or will modify his or her diet to the extent necessary to achieve a meaningful benefit, the best solution for most is the ingestion of nutritional supplements.
The studies supporting the ingestion of antioxidant vitamins, including vitamins A, C and E in combination with zinc oxide and copper, are extremely supportive for retarding dry AMD progression in those with medium to large drusen, geographic atrophy or advanced disease in one eye. In less severe disease, the evidence is softer, but many ophthalmologists, including myself, offer vitamin supplements to those with earlier disease, especially in the face of other significant risk factors. The risk of beta-carotene in the smoker, possibly enhancing lung cancer, or vitamin E possibly worsening heart failure needs to be considered when using these supplements in select patients. Lutein and zeaxanthin are promising as well, and I personally favor nutritional supplements that contain these agents because their use carries little risk, is logical and is supported by level 2 and 3 studies. I also usually recommend omega-3 supplementation in at-risk patients. Again, while level 1 evidence supporting its use is lacking, the risks are low, and use is logical and supported by level 2 and 3 study data. Concerns include the patient on anticoagulant therapy. Recent studies suggest that anti-inflammatory therapy may also have a beneficial effect.
The good news, to me, is that the same habits, diet and nutritional supplements that are, in general, good for our senior patients’ health by reducing the risk of heart disease, stroke and most cancers are those that appear capable of retarding the progression of dry AMD. This fact, and the fact that I personally supplement my own diet with a multivitamin, antioxidant supplement, omega-3s and a baby aspirin, makes it easy for me to recommend these agents to my at-risk patients, even in the earliest stages of AMD.