Age-related macular degeneration (AMD) is one of the major causes of visual impairment in the elderly: it affects central vision, impairing the ability to read and recognize faces while preserving some peripheral vision. It comes in two forms: wet and dry. Dry macular degeneration is by far more common, but wet macular degeneration, involving the proliferation of blood vessels, is more severe.
There is evidence that antioxidant vitamin supplementation may slow the progression of the dry type when it is already established and moderately severe, but the published evidence does not support the use of these supplements for prevention or for patients with early stages of the disease. Some people are using it for prevention, but there is concern that the risks might exceed any benefit. Of more concern, it appears that a manufacturer’s (Bausch & Lomb’s) advertising has gone way beyond the available evidence.
This review by the American Academy of Ophthalmology covers the subject well.
A Cochrane review found that the evidence for effectiveness of antioxidant vitamin supplements comes mainly from one large trial, the AREDS trial, that was funded by the manufacturer Bausch & Lomb. The AREDS study used vitamin C, 500 mg; vitamin E, 400 IU; beta-carotene, 15 mg (approximately 25,000 IU vitamin A); zinc 80 mg as zinc oxide; and copper, 2 mg, as cupric oxide. (The copper was added to prevent copper-deficiency anemia, an adverse effect of high-dose zinc.)
The effect was statistically significant but modest. Patients taking the antioxidant and zinc supplement had a 23% chance of developing vision loss from advanced AMD compared to a 29% chance of developing vision loss from advanced AMD for patients taking a placebo pill.
The Cochrane review concluded
The generalisability of these findings to other populations with different nutritional status is not known. Further large, well-conducted randomised controlled trials in other populations are required. Long-term harm from supplementation cannot be ruled out. Beta-carotene has been found to increase the risk of lung cancer in smokers; vitamin E has been associated with an increased risk of heart failure in people with vascular disease or diabetes.
Bausch & Lomb has been selling a product called PreserVision Eye Vitamin AREDS Formula. It contains the same combination of vitamins C, E, beta carotene and zinc that was shown to slow the progression of moderate to advanced macular degeneration in the AREDS trial. The authors of that trial recommended this treatment for patients with extensive intermediate size drusen (deposits seen on ophthalmoscopy that are characteristic of AMD), at least one large druse, noncentral geographic atrophy in one or both eyes, or advanced AMD or vision loss due to AMD in one eye, and without contraindications such as smoking.
Bausch & Lomb has tried to improve their formula to reduce the risk associated with beta carotene. Their PreserVision Eye Vitamin AREDS 2 Formula omits the beta carotene and adds lutein and zeaxanthin, as well as omega-3 fatty acids. Is the new formula better? We don’t know, because the results of the AREDS 2 trial to test it will not be available until 2013. The product has already been recalled for reformulation after some patients reported difficulty swallowing the soft gels or experiencing a choking sensation. The recall affects only the US: the product is still available in Europe and other parts of the world, and we can expect to see it back on our shelves as soon as it is put into an easier-to-swallow form.
Bausch & Lomb has been advertising their AREDS 2 Formula as “the latest scientific advancement in eye vitamin therapy” and has urged ophthalmologists to give it to their patients. A recent article in The Medical Letter criticized them, saying “That seems premature at best.” Much harsher words could be used.
Bausch & Lomb also sells other products (Ocuvite, Ocuvite Lutein, etc.) that contain lower amounts of the vitamins and minerals used in the AREDS trial, sometimes with other ingredients added, like lutein and omega-3. The rationale for products with these dosages is hard to fathom.
Is this Big Pharma or Big Supplement? The products carry the FDA warning “not intended to diagnose, treat, cure or prevent any disease,” yet they are clearly being marketed to treat a disease.
Should everyone with moderately severe AMD be taking antioxidant supplements? I’m not sure. Since there is little else to try, if I had advanced AMD I might be tempted. But I think caution is warranted due to the following red flags:
- Evidence boils down to one study funded by manufacturer.
- Not replicated.
- Concerns about harmful side effects; no long-term safety data.
- Modest effect.
- No clear rationale for the particular combination and dosage of ingredients.
- Hype by the manufacturer.
This article was originally published in the Science-Based Medicine Blog.