Effect of topical brinzolamide on visual function and waveform in patients of infantile nystagmus syndrome: A randomized control trial.

Purpose: To evaluate the effect of topical carbonic anhydrase inhibitor (brinzolamide) versus placebo on visual function and waveforms in infantile nystagmus syndrome (INS).
Design: Prospective, placebo-controlled, double-blind, cross-over study.
Methods: Setting- A tertiary eye care center. Patients- Cases of idiopathic INS with and without abnormal head posture aged ≥10 years who had not received previous treatment for nystagmus. Intervention- Patients were randomized into two groups. Group 1 was given placebo for 3 months, and after a washout period of 7 days started on topical brinzolamide for the next 3 months. In group 2, the order was reversed. The drops were administered topically three times (every 8 hours) in both eyes. Outcome measure- Binocular best corrected visual acuity (BCVA) using the ETDRS chart, eXpanded nystagmus acuity function (NAFX) score and INS waveforms obtained from eye movement recordings, intraocular pressure (IOP) by Goldmann applanation tonometer, near stereopsis by TNO stereo test, and change in abnormal head posture before and after intervention in the null position.
Results: A total of 29 cases completed the study (23 with abnormal head posture; 6 without abnormal head posture).
A significant improvement was noted in INS waveform characteristics, mean NAFX score (P < 0.001), and mean binocular visual acuity (P < 0.001) with topical brinzolamide in comparison to baseline as well as placebo. No significant change in head position and stereopsis was noted. No side effects were reported with 3 months of brinzolamide therapy.
Conclusions: While brinzolamide shows improvement in visual acuity and NAFX score in idiopathic INS, its clinical significance needs further evidence.
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