The Effect of Horizontal Rectus Muscle Surgery on Clinical and Eye Movement Recording Indices in Infantile Nystagmus Syndrome

Abstract

To determine the relationship between horizontal rectus muscle surgery and eye movement recording in infantile nystagmus syndrome. 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. 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). Horizontal rectus muscle surgery in subjects with infantile nystagmus syndrome improves the visual acuity and nystagmus intensity.