Reduction of congenital nystagmus amplitude with auditory biofeedback

Purpose: Treatment options for congenital nystagmus without null position a re limited. The purpose of this study was to evaluate the role of auditory biofeedback in controlling congenital nystagmus. Methods: Ten patients with congenital nystagmus without null position underwent 6 sessions (twice a w eek for 3 weeks) of auditory biofeedback. Each half-hour session had simult aneous electronystagmographic recording done during the session. Results: T he patients could reduce the nystagmus during the treatment sessions. Mean amplitude (degrees) of nystagmus was reduced from 6.28 +/- 4.94 to 3.05 +/- 2.48 (P = .028) and mean intensity (amplitude x frequency) was reduced fro m 33.37 +/- 22.84 to 13.35 +/- 7.99 (P = .0174), but the mean frequency cha nge was not significant, from 5.8 +/- 1.05 to 4.98 +/- 1.35 (P = .148). The mean amplitude and mean intensity decreased by 51% and 60%, respectively. After completion of the session, although a subjective improvement was repo rted, the patient's binocular visual acuity on Snellen's charts and contras t sensitivity did not show any significant change. Also no sustained benefi t was noted because the electronystagmographic recordings reverted to basel ine after the auditory stimulus for biofeedback was discontinued. Conclusio n: Simultaneous electronystagmographic recording shows significant reductio n of nystagmus amplitude and intensity because of auditory biofeedback only during the treatment session. The beneficial effect does not persist after the auditory stimulus is discontinued. No objective effect on visual acuit y and contrast sensitivity was noted after the therapy.