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

To determine the effect of horizontal rectus muscle surgery on visual acuity, head posture and electronystagmographic indices in patients with congenital nystagmus. This prospective comparative case series was conducted on 58 patients with congenital nystagmus over a period of three years. Patients were divided into three groups: the first group (29 cases) had head posture less than 20D, binocular visual acuity (BOVA) less than 20/30 and tropia less than 30D and underwent large recession of all four horizontal rectus muscles; the second group (23 cases) had head posture less than 20D, BOVA < 20/30 and tropia more than 30D who underwent large recession of two horizontal rectus muscles; and the third group (6 cases) had head posture more than 20D with any BOVA or tropia who underwent Kestenbaum-Anderson surgery. Mean age of the patients was 18.7±9.1 years and mean follow-up period was 17.5±7.4 months. Visual acuity improved in all three study groups and was statistically significant in the 2-rectus group (P < 0.001). The speed and amplitude of nystagmus waves decreased 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-rectus groups and a small hyperopic shift was found in the Kestenbaum-Anderson group. Statistically significant improvement was achieved in eye deviation in the 2-rectus group and in head posture in the Kestenbaum-Anderson group (P < 0.001). Horizontal recti surgery in congenital nystagmus can improve visual acuity, ocular deviation and abnormal head posture, which is particularly marked with 2-rectus recession. Electronystagmographic indices improve especially with 4-rectus recession.