Levodopa-carbidopa may improve vision loss in indirect traumatic optic neuropathy.

Abstract

To compare the effect of levodopa-carbidopa on the visual outcome of patients with indirect traumatic optic neuropathy (ITON), this randomized, double-blind, placebo-controlled study was conducted on 32 patients with ITON within 6 days after trauma. Patients underwent a complete ocular examination, pattern visual evoked potential (PVEP) testing, and high-resolution orbital computed tomography (CT) scanning. All patients received high-dose intravenous methylprednisolone, and levodopa was also administered to the levodopa group. The main outcome measures were best corrected visual acuity and PVEP results at the last-completed examination. The study was completed on 16 patients in the levodopa group and 10 patients in the placebo group because the others were lost to follow-up. There were no statistically significant differences for age, sex, involved eye, ocular and CT scan findings, pretreatment visual acuity, frequency of recordable PVEPs, and follow-up. In the levodopa group the visual acuity improved significantly after treatment (p = 0.009), but not in the placebo group (p = 0.34). After treatment the visual acuity in the levodopa group was 2.1 ± 2.1, and in the placebo group was 3.9 ± 1.2 (p = 0.008). In those who had visual acuity less than or equal to figure count, significant improvement in visual acuity was observed in the levodopa group (p = 0.03), but not in the placebo group (p = 0.34). However, the final visual acuity in these patients was comparable after treatment (p = 0.21). Nine patients (56.2%) in the levodopa group, and 1 (10%) in the placebo group, experienced improvement in visual acuity (p = 0.02). The frequency of unrecordable PVEPs were comparable in both groups (p = 0.09). Patients treated with levodopa within 6 days of onset of ITON were more likely to experience improvement in visual acuity than those in the placebo group.