As we age, changes occur in the lens of the eye that may cause several degenerative eye diseases common among the elderly. The first step is a growing cloudiness, or opacity, of the lens, and this leads to the development of cataracts. Researchers believed that oxidative stress was an important cause of the process, and likewise that antioxidant nutrients could help to prevent or at least delay it. A recent study of 410 Finnish men reported that low blood vitamin E levels were significantly associated with increased risk for worsening of lens opacity. When they divided the men into four groups, those in the group with the lowest vitamin E had an almost four times greater risk than men in the group with the highest plasma vitamin E. Cigarette smoking was also an important risk factor for lens opacity.

Although there was strong evidence for a protective role of antioxidant nutrients in the development of cataracts, no one had linked these same nutrients to another eye disease in the elderly that is the leading cause of irreversible blindness, age-related macular degeneration (AMD). In AMD, damage occurs to the small central part of the retina, the macula, and the person loses central vision. The theory behind AMD and the antioxidants suggests that these nutrients prevent the disease by protecting the outer retina, an area containing a high concentration of polyunsaturated fatty acids, which are susceptible to oxidative damage. The antioxidants may also keep the blood vessels that feed the macula healthy. More proof for antioxidant protection against AMD, this time for carotenoids, comes from the Eye Disease Case-Control Study (EDCCS). Researchers recruited subjects from five major American ophthalmology clinics aged fifty-five to eighty who had a diagnosis of AMD. They found that carotenoid intake reduced AMD risk, and the relationship was linear, meaning that the higher the intake, the lower the risk. People in the group with the highest carotenoid intake had a 43 percent lower risk compared to other subjects. The study also compared the effects of different carotenoids and found that lutein and zeaxanthin were the most effective in protecting against AMD. The EDCCS authors concluded that “increased intake of foods rich in antioxidants, especially certain carotenoids, may reduce the risk of developing advanced AMD.”