Abstract
Purpose :
To investigate the effectiveness of gabapentin and memantine in infantile nystagmus (IN) on both visual function and eye movement
Methods :
A randomised, triple masked, controlled crossover trial of gabapentin and memantine was performed on 66 participants with IN. Each treatment period was 17 weeks with a 6 week washout period before the next treatment was commenced. Outcome measures were 25% improvement in visual acuity (primary outcome), 25% improvement in eye movement (nystagmus intensity and expanded nystagmus acuity function [NAFX]), absolute change in visual function (visual acuity and reading parameters) and eye movement and descriptive analysis of nystagmus waveforms responding to treatment. Time course of treatment was also assessed to evaluate when the treatments were at their most effective and at what dosage this occurred.
Results :
Gabapentin and memantine did not improve any visual function parameters as a 25% improvement or when assessing the absolute differences. In contrast null region nystagmus intensity (p=0.014) and NAFX (p=0.028) were significantly different for treatment as gabapentin reduced intensity and improved NAFX by 25%. For absolute differences in null region nystagmus intensity gabapentin was also significant (p=0.047). Pendular waveforms prevalently appeared in those participants responding to gabapentin. Treatment, in particular gabapentin, was most effective after initial administration and directly after an increase in the dosage. Baseline measurements were often a predictor for success of treatment; the worse the baseline the more likely treatment would be effective. Gabapentin and memantine were both reasonably well tolerated.
Conclusions :
Gabapentin, and not memantine, significantly reduces eye movement in IN but does not improve visual function. Pendular waveforms appeared to be most sensitive to treatment. Reduction of pendular waveforms support previous studies in acquired pendular nystagmus and may suggest a specific underlying mechanism that is most sensitive to treatment.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.