Effect of Horizontal Rectus Surgery on Clinical and Paraclinical Indices in Congenital Nystagmus

Purpose: To determine the effect of horizontal rectus muscle surgery on visual acuity,head posture and electronystagmographic indices in patients with congenital nystagmus.Methods: This prospective comparative case series was conducted on 58 patients withcongenital nystagmus over a period of three years. Patients were divided into threegroups: the first group (29 cases) had head posture less than 20°, binocular visual acuity(BOVA) less than 20/30 and tropia less than 30Δ and underwent large recession of allfour horizontal rectus muscles; the second group (23 cases) had head posture less than20°, BOVA 20/30 and tropia more than 30 who underwent large recession of twohorizontal rectus muscles; and the third group (6 cases) had head posture more than 20°with any BOVA or tropia who underwent Kestenbaum-Anderson surgery.Results: Mean age of the patients was 18.7±9.1 years and mean follow-up period was17.5±7.4 months. Visual acuity improved in all three study groups and was statisticallysignificant in the 2-rectus group (P 0.001). The speed and amplitude of nystagmus wavesdecreased in all groups which was statistically significant in the 4-rectus group (P values,0.02 and 0.04, respectively). A small myopic shift was seen in the 2-rectus and 4-rectusgroups and a small hyperopic shift was found in the Kestenbaum-Anderson group.Statistically significant improvement was achieved in eye deviation in the 2-rectus groupand in head posture in the Kestenbaum-Anderson group (P 0.001).Conclusion: Horizontal recti surgery in congenital nystagmus can improve visual acuity,ocular deviation and abnormal head posture, which is particularly marked with 2-rectusrecession. Electronystagmographic indices improve especially with 4-rectus recession.