Inferior Rectus Muscle Y-Split for Thyroid-Related Vertical Strabismus.

Incomitant hypotropia in thyroid eye disease can be difficult to manage, especially in the presence of orthotropia with fusion in down gaze and reading position. Recessing the affected ipsilateral inferior rectus muscle may result in an undesirable downgaze diplopia secondary to a hypertropia in downgaze. Various surgical techniques have been described to manage this potential complication including asymmetric recession of both inferior rectus muscles, posterior myoscleropexy operation, and the Scott recess/resect procedure of the contralateral inferior rectus. In 2004, Hoerantner et al. introduced the y-split recession of the medial rectus muscle for near esotropic deviations. The anterior portion of muscle is split and secured in a y-shaped configuration, which reduces the muscle lever arm and helps minimize incomitance and muscle slippage. Unlike the traditional Cüppers Faden, a y-split recession results in torque reduction in all gaze positions. In addition, a y-split recession does not involve scleral passes posteriorly reducing the risk of globe perforation. We report a patient with incomitant strabismus secondary to thyroid eye disease who underwent a combination of traditional recession and y-splitting recession of the contralateral inferior rectus muscle, resulting in good functional alignment in primary gaze and in the reading position.