Randomised double-masked placebo-controlled trial of a treatment for congenital nystagmus

Several therapies have been developed for congenital nystagmus (CN) but without placebo-controlled trials. We investigated a treatment which combined two therapies that had been advocated by several authors and were reported to improve visual acuity (VA). A placebo treatment was designed to mimic the time, attention, 'high tech' apparatus, and the explanation used in the experimental treatment. To each group, 38 subjects with CN were randomly allocated. Their VA and contrast sensitivity (CS) were assessed three times before undergoing treatment for 6 weeks and then once more. An improvement in VA occurred, however, this was not significantly different in the two groups. The improvement in CS was greater in the experimental than in the control group, but the difference failed to reach significance in most statistical tests. We conclude that putative therapies for CN should be assumed to be placebos until proven otherwise with randomized controlled trials.