Abstract
Purpose::
To compare the changes in nystagmus waveform in a recently performed randomized double-masked placebo controlled study on the effects of gabapentin and memantine on patients with congenital nystagmus.
Methods::
Eye movements (250Hz) were recorded from 21 patients with congenital idiopathic nystagmus (CIN) and 27 patients who had congenital nystagmus associated with other ophthalmological conditions (secondary nystagmus, SN). They were compared prior to and following 8 weeks of memantine, gabapentin or placebo treatment. Nystagmus intensity and foveation (measured using the Extended Nystagmus Acuity Function, NAFX) were measured at positions from -24° to 24° eccentricity at 3° intervals along the axis of the nystagmus. Changes in intensity and NAFX before and after medication were estimated at the null point and from the mean of all positions. These were compared to measured changes in visual acuity.
Results::
Significant improvements in nystagmus intensity (F=7.7, p=0·001) and foveation (F=7.8, p=0·001) were evident at null point, with the nystagmus intensity showing improvements (F=4.7, p=0·02) for the mean of all positions from -24° to 24°. Patients with CIN showed similar improvements in nystagmus intensity and foveation as patients with SN, in contrast to visual acuity which improved much more in the CIN group compared to the SN group.
Conclusions::
Gabapentin and memantine reduce oscillations in both congenital idiopathic nystagmus and in congenital nystagmus associated with other ophthalmological conditions.
Clinical Trial::
MHRA CTA no. MF/8000/11727 MF/8000/11730
Keywords: eye movements • drug toxicity/drug effects • neuro-ophthalmology: cortical function/rehabilitation