The Effect of Bilateral Horizontal Rectus Recession on Visual Acuity, Ocular Deviation or Head Posture in Patients with Nystagmus

Purpose: This work was undertaken to evaluate the effect of bilateral horizontal rectus recession on visual acuity, ocular deviation and head posture in patients with nystagmus. Methods: Twenty patients underwent recession of 4 horizontal rectus muscles to dampen the nystagmus. At least 2 muscles were recessed posterior to the equator. Results: Monocular and binocular visual acuity improved from 1 to 3 Snellen lines after the procedure in 13 patients (76.5%). Visual changes in log MAR notations were statistically significant with Wilcoxon analysis in each and both eyes. Preoperative binocular visual acuity was 0.73 ± 0.26 log MAR that reached to 0.62 ± 0.32 log MAR after surgery (P = 0.02). The greatest improvement was observed in patients with congenital motor nystagmus. Ten patients had horizontal strabismus in addition to nystagmus before the surgery. One-millimeter additional recession of both medial rectus muscles caused an average reduction of 6 PD in esotropia. Corresponding figures for similar additional recessions of the lateral rectus muscles was 11 PD for correction of exotropia. Abnormal head posture decreased in all the cases and improved completely in most of them. Conclusions: Large horizontal rectus recession can improve visual acuity and decrease nystagmus in sensory and motor types. By revision in surgical planning, strabismus and abnormal head posture can also be corrected.