Effect of Levodopa-Carbidopa on Visual Function in Patients with Recent Nonarteritic Anterior Ischemic Optic Neuropathy

To evaluate the effect of levodopa-carbidopa on improvement of visual acuity, color vision, and visual field in patients with nonarteritic anterior ischemic optic neuropathy (NAION) with onset less than 6 wks. In this double-blind randomized controlled trial, 13 patients were treated with levodopa-carbidopa and 12 patients were treated with placebo for 3 weeks. After 6 months, visual acuity (evaluated by Snellen chart), color vision (evaluated by Ishihara pseudoisochromatic plate), and visual field (evaluated by Humphrey automated perimetry central 30-2) were evaluated. Mean visual acuity in the treatment group was 1.007 LogMAR (1/10) at beginning of study and 0.75 LogMAR (4/10) at the end. Improvement of visual acuity in this group was 3 lines of Snellen chart (P=0.001). In the placebo group, mean visual acuity was 0.85 LogMAR (3/10) at the beginning of study and 0.75 LogMAR (4/10) at the end. Improvement of visual acuity in this group was 1 line of Snellen chart (P=0.013). Mean color vision in treated eyes was 4/14 at beginning of study and 5.76/14 at the end. In the placebo group this value was 4.3/14 at ending. There was no statistically significant difference in color vision between two groups both at beginning and at the end of treatment. Visual field improvement did not show any difference between the two groups (P=0.93). Although levodopa-carbidopa significantly improved visual acuity, other aspects of visual function did not show significant changes. Other therapeutic modalities should be tried.