the effects of horizontal recti surgery on clinical and paraclinical indices in congenital nystagmus

purpose: to determine the effect of horizontal recti surgery on visual acuity and head posture and electronystagmographic indices in patients with congenital nystagmus. methods: this prospective comparative case series was conducted on 58 patients with congenital nystagmus who were referred to our clinic over three years. patients were divided into three groups: the first group (29 cases) had head posture less than 20°, binocular visual acuity (bva) less than 20/30 and tropia less than 30d who underwent large recess of four horizontal rectus muscles; the second group (23 cases) had head posture less than 20°, bva < 20/30 and tropia more than 30d who underwent large recess of two horizontal rectus muscles; and the third group (6 cases) had head posture more than 20° with any bva or tropia who underwent kestenbaum-anderson surgery. results: 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 groups which was statistically significant in the 2-rectus group (p=0.0001). the speed and amplitude of nystagmus waves were decreased in all groups which were statistically significant in the 4-rectus group (p=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 (p<0.001) improvement was achieved in eye deviation in the 2-rectus group and in head posture in the kestenbaum-anderson group. conclusion: horizontal recti surgery in congenital nystagmus can improve visual acuity, strabismus and abnormal head posture, especially with 2-rectus recession. nystagmus intensity indices improve especially with 4-rectus recession.