Surgical Management of Dissociated Deviations

Abstract

Core Messages Dissociated deviation (DD) manifests as a slow, intermittent, and variable vertical (DVD), horizontal (DHD), and torsional (DTD) movement. It is usually found in patients with early onset strabismus and profound sensorial anomalies. The treatment for patients with DD requires a specific surgical approach to improve the vertical, horizontal, and torsional misalignment simultaneously. DVD neither disappears nor improves over time; the aim of treatment is to obtain a latent deviation. Symmetric dissociated vertical deviation (DVD), with good bilateral visual acuity (VA), without oblique muscle dysfunction: four surgical alternatives: (1) Bilateral large superior rectus (SR) recession. (2) Bilateral retroequatorial myopexy (posterior fixation) of the SR combined with or without recession of these muscles. (3) Four oblique muscles weakening procedure. (4) Bilateral inferior rectus (IR) resection. Bilateral DVD with deep unilateral amblyopia: three available procedures: (1) Unilateral SR recession, (2) Unilateral inferior oblique anterior transposition (IOAT), and (3) Unilateral IR resection or tucking. DVD with inferior oblique overaction (IOOA) and V pattern: (1) Bilateral IOAT. (2) Bilateral SR recession added to bilateral inferior oblique (IO) recession. DVD with superior oblique overaction (SOOA) and A pattern: (1) Bilateral SR recession, (2) Bilateral SR recession + superior oblique (SO) posterior tenectomy, or (3) Four oblique muscles weakening procedure. Symmetric vs. Asymmetric surgeries for DVD: Bilateral symmetric procedures are performed for cases with bilaterally symmetric DVD. Cases with asymmetric DVD are more common. These cases require asymmetrical techniques. Dissociated horizontal deviation (DHD): The main diagnostic sign of DHD is the presence of a horizontal deviation, esotropia (ET), or exotropia (XT) that changes with fixation of each eye, unrelated to different accommodation, muscle weakness, or restriction. The technique most used for DHD is unilateral lateral rectus (LR) recession. Retroequatorial myopexy (posterior fixation) of the LR with recession of this muscle is recommended by certain authors. Bilateral LR recession is indicated when XThis bilateral; unilateral or bilateral medial rectus (MR) recession when the patient exhibits ET instead of XT. Performing an LR recession added to MR advancement is a valid alternative in cases with previous surgery on the medials. Dissociated torsional deviation (DTD): Children with DD frequently have head turn but they also have head tilt. The head tilt can be toward the shoulder of the fixing eye (direct tilt) or toward the contralateral side (inverse tilt). We have to take into account the head tilt to attempt to improve the head position when performing surgery. Obtaining long-term control of the deviation in patient with DD is difficult; a successful outcome in the postoperative period does not guarantee the final alignment. In treated patients with DD, some kind of movement is always detected when performing the cover test. DVD never disappears completely and the dissociated behavior in DHD also persists when testing under slow cover test.