Effect of second-generation antiepileptic drugs on diplopia: a meta-analysis of placebo-controlled studies.

Different antiepileptic drugs (AEDs) may cause similar adverse effects, one of which is diplopia. However, the AEDs causing diplopia and the dose-response effect of each drug remains uncertain. In this study, we compared several second-generation AEDs to find out whether they would contribute to the risk of diplopia and their effect-causing dose. A meta-analysis was performed on 19 studies in agreement with our inclusion criteria. The results showed that eight commonly used second-generation AEDs (gabapentin, levetiracetam, oxcarbazepine, lamotrigine, pregabalin, topiramate, vigabatrin and zonisamide) could cause diplopia. The reported odds ratios (ORs) ranged from 1.406 to 7.996. Ranking risks from the highest to the lowest ORs of the eight AEDs of any dose resulted in the following order: use of oxcarbazepine (7.996), levetiracetam (7.472), lamotrigine (5.258), vigabatrin (3.562), pregabalin (3.048), topiramate (2.660), gabapentin (1.966), zonisamide (1.406). Taking into account the ORs above, we can conclude that second-generation AEDs of any dose may cause diplopia. However, the levetiracetam-caused diplopia needs to be further studied according to the data (OR, 7.472; 95% confidence interval, 0.375-148.772). These findings ask for better concerns about patients' quality of life when giving antiepileptic treatments.