Antioxidants and Age-Related Macular Degeneration

It is estimated that around 5% of the general population suffer from age-related macular degeneration (AMD),[1] where extracellular material known as drusen accumulate under the retina at the back of the eye and which can eventually lead to blurred or a loss of vision. It has been suggested that antioxidants may help prevent or delay development of AMD in people who do not suffer the condition by protecting the retina against oxidative stress, but it is unclear as to whether this is the case.

A systematic review in the Cochrane Database by Evans and Lawrenson looked at the effectiveness of antioxidant supplements as treatment in people who already had AMD,[2] and found that taking a multivitamin antioxidant vitamin may delay the progression of AMD when compared to a placebo or no treatment (odds ratio 0.72, 95% CI 0.58-0.90). The authors also conducted a systematic review looking at whether there was an association between taking antioxidant vitamins (carotenoids, vitamin C, vitamin E) or minerals (selenium, zinc) and the development of AMD in people without AMD.[3] Five RCTs were included, with a total of 76,756 individuals without AMD. These studies all looked at the use of various supplements against placebo. Generally, the various studies found that there was no effect of supplements on development of AMD, while in some cases there was evidence of an increased risk (see table below).

Comparison	No. of studies	Disease	Risk Ratio (95% Confidence Interval)
Vitamin E vs. placebo	4	AMD	0.97 (0.90-1.06)
		Late-stage AMD	1.22 (0.89-1.67)
Beta-carotene vs. placebo	2	AMD	1.00 (0.88-1.14)
		Late-stage AMD	0.90 (0.65-1.24)
Vitamin C vs. placebo	1	AMD	0.96 (0.79-1.18)
		Late-stage AMD	0.94 (0.61-1.46)
Multivitamin vs. placebo	1	AMD	1.21 (1.02-1.43)
		Late-stage AMD	1.22 (0.88-1.69)

— Peter Chilton, Research Fellow

References:

1. Owen CG, Jarrar Z, Wormald R, Cook DG, Fletcher AE, Rudnicka AR. The estimated prevalence and incidence of late stage age related macular degeneration in the UK. Br J Ophthalmol. 2012; 96(5): 752-6.
2. Evans JR, Lawrenson JG. Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration. Cochrane Database Sys Rev. 2017; 7: CD000254.
3. Evans JR, Lawrenson JG. Antioxidant vitamin and mineral supplements for preventing age-related macular degeneration. Cochrane Database Sys Rev. 2017; 7: CD000253.