Supplements may benefit AMD patients

Fort Lauderdale, FL-Supplements of high-dose vitamins C and E and betacarotene may provide some benefit to patients who already have age-related macular degeneration (AMD), said Thomas Friberg, MD.

He reported that supplements seem to decrease the risk of additional vision loss in the eye with AMD and also in the fellow eye, although the effect over a course longer than the Age-Related Eye Disease Study (AREDS) is unknown. Dr. Friberg described the study on behalf of the AREDS Research Group at the annual meeting of the Association for Research in Vision and Ophthalmology.

"One of the questions that physicians face who care for patients with AMD is if the AREDS formula would have a benefit for those who have already had visual disturbances related to AMD," said Dr. Friberg, professor, department of ophthalmology, University of Pittsburgh Eye & Ear Institute, Pittsburgh.

Patients who were included in AREDS received one of four possible treatments: zinc alone, antioxidants alone, a combination of antioxidants and zinc, or a placebo. The antioxidants consisted of 400 units of vitamin E, 500 mg of vitamin C, and 15 mg of betacarotene; the zinc was administered as 80 mg of zinc oxide.

Investigators evaluated the effect of supplementation in patients who already had had an AMD event at baseline to determine if supplementation had any effect on visual acuity that exceeded 20/100.

Dr. Friberg reported a disparity between the group that received antioxidants and the group that received placebo; the group that received antioxidants had a positive effect on visual acuity. This comparison reached statistical significance.

However, the comparisons between placebo and zinc and between placebo and the antioxidants and zinc did not indicate that there was any difference in the effect on visual acuity.

Investigators also evaluated the effect of the various treatments on patients with 20/200 or better visual acuity at baseline. As with the previous comparison, the biggest effect was seen between the group that received placebo and the group that received antioxidants, although the effect was not as great as that in the patients who had 20/100 vision at baseline, he said.

Effect of antioxidants

The use of antioxidants also seemed to have an effect on the number of letters lost over time. In the patients with worse visual acuity at baseline (i.e., those with 20/200 or better vision), the antioxidant effect was less than in the patients with 20/100 vision at baseline.

The AREDS group also attempted to determine if incident AMD developed in patients randomly assigned to antioxidants during the course of the study and whether the antioxidants had any effect in eyes with 20/100 or better when the advanced AMD occurred and also in patients with visual acuity of 20/200 or better.

In the patients with incident AMD, no difference was found between groups compared with placebo. In those with 20/200 or better at the time of the development of advanced AMD, there was no difference.

"In eyes with advanced AMD and 20/100 or better vision at baseline, treatment with AREDS antioxidants was significantly better compared with placebo, although the difference was nominal," Dr. Friberg said. "The other evaluations resulted in no significant difference between the AREDS supplement and placebo; however, protective effect was suggested and the supplement did not harm the patients.

"It is unknown if there is more of a protective effect over time," he said. "The result raises a provocative question of whether supplements should be given to patients with advanced AMD in both eyes."