Dr. Chew said the AREDS study researchers recommend replacing the beta-carotene in supplements with lutein and zeaxanthin.

WSJ: The Crucial Years for Protecting Your Eye Health

The study found a similar beneficial effect for people with cataracts who don't normally get a lot of lutein and zeaxanthin in their diet.

WSJ: The Crucial Years for Protecting Your Eye Health

Short sleepers tended to eat less vitamin C, tap water and selenium (found in nuts, meat and shellfish) consumption, but more lutein or zeaxanthin, which are found in green, leafy veggies.

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The latest part of the study, which involved about 4, 000 participants, also looked at the effect of replacing beta-carotene in the supplements formulation with lutein and zeaxanthin because of studies that found former smokers who take beta-carotene have a higher incidence of lung cancer.

WSJ: The Crucial Years for Protecting Your Eye Health

In the second phase of AREDS, to be published in this month's Journal of the American Medical Association, researchers identified additional nutritional supplements the carotenoids lutein and zeaxanthin, found in foods such as spinach, kale and broccoli that further reduce the risk and progression of AMD, especially when a person's diet is already low in these nutrients.

WSJ: The Crucial Years for Protecting Your Eye Health