Torsional strabismus and vertical rectus muscle surgery in thyroid eye disease

To assess the torsional component in patients with vertical strabismus due to thyroid eye disease (TED) and its course after vertical rectus muscle surgery.

Retrospective chart review of patients undergoing vertical strabismus surgery for TED between 1998 and 2017, having undergone pre- and postoperative Harms tangent screen examination.

Forty patients (27 women) were identified. A torsional component was present in all patients. Thirty-three patients had a mean excyclotorsion of 4.5° in primary position, increasing to 8.2° in upgaze, associated with restricted elevation. Inferior rectus muscle recession (n=29) reduced the excyclotorsion in all cases. A 4.4° mean incyclotorsion was present in primary position in 7 cases, increasing to 7.1° in downgaze. Superior rectus muscle recession reduced the incyclotorsion in 5/6 cases. The torsional surgical dose-effect relationship was correlated with the amount of preoperative torsion. The field of binocular single vision improved from 6.5% preoperatively to 71.1% after surgery.

Ocular torsion is common in vertical strabismus secondary to TED and is significantly improved by vertical rectus muscle surgery alone. Surgery should be planned according to vertical deviation and motility limitation, and vertical rectus muscles surgery should be considered the first line of treatment, with selective oblique muscle surgery as a second-line option, which was unnecessary in our series.