Effect of levodopa and carbidopa on recovery of visual function in patients with nonarteritic anterior ischemic optic neuropathy of longer than six months' duration.

PURPOSE

We conducted a pilot clinical trial to determine the efficacy of levodopa in promoting visual recovery in eyes with nonarteritic anterior ischemic optic neuropathy of greater than six months' duration.

METHODS

This prospective, randomized, double-masked, placebo-controlled clinical trial involved 20 subjects with nonarteritic anterior ischemic optic neuropathy of 30 months' mean duration. Subjects were randomly assigned to receive either low-dose levodopa and carbidopa or a placebo for three weeks. At 12 weeks after the baseline visit, the levodopa group then was provided a higher, conventional dose of levodopa and carbidopa for three more weeks. Change in visual function was monitored at four, 12, 16, and 24 weeks after the baseline visit.

RESULTS

At 12 weeks after the baseline visit, the levodopa group experienced a significant (P = .016) mean difference in improvement of visual acuity of 5.9 letters from the placebo group. At 24 weeks after the baseline visit, a significant treatment effect (P = .036) for visual acuity was still evident; the levodopa group had a mean gain in improvement of 7.5 letters difference from baseline from the placebo group. Three subjects in the levodopa group experienced a doubling of the visual angle as denoted by a gain of at least 15 letters. Significant improvement was not observed for color vision (P = .82) or mean deviation of visual field loss (P = .82).

CONCLUSION

The study found significant improvement of visual acuity among subjects receiving levodopa and carbidopa despite long-standing visual loss from nonarteritic anterior ischemic neuropathy. Confirmation of our results is awaited from larger population studies and with a longer follow-up time interval regarding the efficacy of levodopa in reversing visual loss in this disease.