Pharmacological enhancement of treatment for amblyopia.

Background: The purpose of this study was to compare a weight-adjusted dose of carbidopa- levodopa as treatment adjunctive to occlusion therapy with occlusion therapy alone in children and adults with different types of amblyopia.

Methods: This prospective study included 63 patients with amblyopia classified into two groups, ie, an occlusion group which included 35 patients who received occlusion therapy only and a pharmacological enhancement group which included 28 patients who received oral carbidopa-levodopa together with occlusion therapy for 6 weeks.

Results: The mean logarithm of the minimal angle of resolution (logMAR) of the eyes with amblyopia was not significantly different in the occlusion group (0.52, 0.52, and 0.51) than in the pharmacological enhancement group (0.58, 0.49, and 0.56) at three follow-up visits (at months 1, 3, and 12, respectively). There was a highly significant improvement in mean logMAR of amblyopic eyes compared with baseline in both occlusion groups (from 0.68 to 0.52, from 0.68 to 0.52, and from 0.68 to 0.51) and in the pharmacological enhancement group (from 0.81 to 0.58, from 0.81 to 0.49, and from 0.81 to 0.56) at the month 1, 3, and 12 visits (P = 0.01, P = 0.01, and P = 0.001, respectively). The improvement of mean logMAR in the subgroup of patients older than 12 years was greater in the pharmacological enhancement group (42.5%) than in the occlusion group (30%). The improvement of mean logMAR in the subgroup of patients with severe amblyopia was greater in the pharmacological enhancement group (34.3%) than in the occlusion group (22%).

Conclusion: Significant improvement was reported in both groups at all follow-up visits over 1 year. Regardless of the etiology of amblyopia, levodopa-carbidopa may be added to part-time occlusion in older patients as a means of increasing the plasticity of the visual cortex. Levodopa may add to the effect of occlusion in severe amblyopia and bilateral amblyopia.