Abstract
Purpose::
We recently performed a randomized double-masked placebo controlled study to investigate the effect of gabapentin and memantine on patients with congenital nystagmus. Here we report the effects of gabapentin and memantine on patients included in the study with a torsional component to their congenital nystagmus
Methods::
Patients included in the study had a diagnosis of idiopathic nystagmus (IN) or secondary nystagmus to other pathology (SN).Torsional eye recordings were taken at the first visit when the drugs were commenced and the forth visit after which the drugs were stopped. The dosage of the drug was increased from 600 mg to 2400 mg for gabapentin and from 5 mg to 40 mg for memantine over an 8 week period. LogMar VA was taken binocularly and monocularly and a three dimensional pupil and iris tracking video-oculography technique was used to measure the torsional nystagmus. Patients fixated at primary position both binocularly and monocularly throughout testing.
Results::
A total of 8 patients with congenital nystagmus had a torsional component (IN: n=5; SN: n=3). The amplitude of torsional nystagmus was reduced in all 5 patients that were commenced on memantine with a mean reduction of 3.43º (73.3%), 1.35º(35.4%) and 2.08º(71.7%) fixing binocularly, and with the right and left eyes, respectively. Of the three patients that were on Gabapentin, the mean reduction in torsional nystagmus amplitude was 0.41°(38.4%),1.08°(100%) and 1.26°(80.6%) for binocular, and right and left eye viewing, respectively. Three of the patients on memantine also demonstrated an improvement in visual acuity with an improvement of 0.1, 0.1 and 0.5 LogMAR units for binocular viewing, 0.08, 0.16, 0.7 LogMAR units for RE viewing and 0.08, 0.12, 0.5 LogMAR units for LE viewing. One of the subjects on Gabapentin treatment displayed an improved VA acuity by 0.06, 0.02 and 0.06 LogMAR units for binocular, RE and LE viewing respectively. One further subject showed VA improvement of 0.14 LogMAR units in the RE only.
Conclusions::
The torsional component of congenital nystagmus also improves with pharmacological treatment using Memantine and Gabapentin.
Clinical Trial::
MHRA CTA no.MF/8000/11727