Effect of Levodopa on Visual Function in Amblyopia

ABSTRACT

Recently many attempts have been made to find a meaical treatment for amblyopes who failed or were stable to respond to conventional occlusion therapy. To evaluate the efficacy and tolerability of levodopa, double-masked placebocontrolled study was performed on 20 older children with strabismic and anisometropic amblyopia. 12 subjects received 2.0mg/0.5mg/kg of levodopa/benzerazide and 8 subjects received 2.0mg/kg of placebo(lactose). Snellen visual acuity, steroacuity, Worth 4 dot test were measured to assess efficacy at baseline, 1 and 5 hours after drug ingestion. Tolerance was assessed by questionnare. Log Snellen fraction in the amblyopic eyes of levodopa group improved by 0.1(one line), from an overall average of 0.49 to 0.39 at 1 hour and 5 hours after drug ingestion(p<0.01). No significant changes in visual acuity were found in the dominant eyes of levodopa group and in both eyes of placebo group. In levodopa group the improvements of stereoacuity (more than 1 step) were by 50% at 1 hour and 83% at 5 hours after drug ingestion, but in placebe group, only 13% at both 1 and 5 hours after. No changes in Worth 4 dot test were found in both levodopa group and placebo group. Side effects reported in the study were transient episodes of nausea, emesis and sleepiness, but similar between two groups. In conclusion, we found levodopa is efficacious in temporarily improving visual function in amblyopic eyes, and further investigation with a large number of patients and longer duration of follow up is needed.