The effect of horizontal rectus muscle surgery on clinical and eye movement recording indices in infantile nystagmus syndrome.

Objective: To determine the relationship between horizontal rectus muscle surgery and eye movement recording in infantile nystagmus syndrome.

Methods: In this prospective, interventional, non-randomized study, patients with infantile nystagmus syndrome were assigned to one of three treatment groups. Group I with head postures of less than 20 degrees , binocular visual acuity of less than 20/30, and heterotropia less than 30(Delta) underwent recessions of all 4 horizontal rectus muscles. Group II with head postures of less than 20 degrees , binocular visual acuity of less than 20/30, and heterotropia more than 30(Delta) underwent large recessions of two horizontal rectus muscles. Group III with head postures of more than 20 degrees underwent Kestenbaum-Anderson surgery. Baseline and follow-up evaluations included best corrected visual acuity for distance and near, cycloplegic refraction, head posture, and eye movement recordings.

Results: Fifty-eight (58)patients with a mean age of 18.7 (SD +/- 9.10 years) were enrolled. Four horizontal rectus muscle recessions were performed in 29 cases, 2 rectus recession in 23, and Kestenbaum-Anderson surgery in 6 cases. Mean follow-up period after surgery was 18 +/- 7.4 months. Distance visual acuity improved in all three groups, but only in the 2 rectus muscle surgery group was the change significant for both monocular and binocular vision (P < 0.001). In all 3 groups speed and amplitude of nystagmus waves were changed in positive or negative direction but only in 4-recti recession decrease was statistically significant (P = 0.02 & 0.04).

Conclusion: Horizontal rectus muscle surgery in subjects with infantile nystagmus syndrome improves the visual acuity and nystagmus intensity.