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R.J. McLean, S. Thomas, F.A. Proudlock, I. Gottlob; A Randomized Double–Masked Placebo Controlled Study Investigating the Effect of Memantine and Gabapentin on Congenital Nystagmus . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2658.
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In acquired nystagmus, there is some evidence of a positive effect of gabapentin or memantine, both of which have anti–glutaminergic action. There are no studies of effects of drugs on congenital nystagmus, and only a few case reports. We conducted a randomized double–masked placebo controlled study to investigate the effect of gabapentin and memantine on patients with congenital nystagmus.
24 patients with congenital idiopathic nystagmus (IN) and 24 with congenital nystagmus associated to other ophthalmological conditions (secondary nystagmus, SN) (17 with albinism, 4 with achromatopsia, 1 with optic nerve hypoplasia, 1 with congenital optic nerve atrophy and 1 with congenital cataracts) were included in the study. From each group 8 patients were randomised to treatment with memantine, gabapentin or placebo (16 in total for each medication). Patients came for 5 visits. The dosage of the drug was escalated from 600 mg to 2400 mg for gabapentin and from 5 mg to 40 mg for memantine over a period of 8 weeks. Patients were examined with logMar VA with each eye and both eyes open and infrared eye movement recordings (Eyelink pupil tracker, 250 Hz) at each examination. Eye movements were measured at null point and at different fixation eccentricities. VA estimated from foveation was measured with the NAFX function.
A significant (p =0.006) increase of VA by a mean of 1.1 logMAR lines was found in the group of patients receiving memantine. Patients receiving gabapentin showed a tendency to improve but this was not significant. Patients with IN showed more improvement in VA than patients with SN. The patient with the best VA outcome (improvement 6 lines) was from the IN group on memantine. The amplitude of nystagmus also decreased significantly by a mean of 1.3° with memantine treatment (p<0.05). Four patients on memantine could not tolerate the full drug dosage because of dizziness and tiredness, other patients had mild side effects such as headache, tiredness and dizziness but tolerated the full dosage.
This is the first randomised placebo double–masked controlled study showing that pharmacological treatment, in particular with memantine, is effective in congenital nystagmus.
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