[Lower eyelid retraction after inferior rectus recession in thyroid eye disease]

The involvement of extraocular muscles (EOMs) in the inflammatory process in thyroid eye disease (TED) often leads to fibrosis, persistent restrictive strabismus, and binocular diplopia. The inferior rectus muscle (IRM) is most commonly affected, resulting in vertical strabismus and hypotropia with significant limitation of upward gaze. Surgical management of restrictive strabismus in TED aims to increase the range of binocular eye movements, eliminate binocular diplopia, and correct the cosmetic defect associated with strabismus. The "gold standard" surgery involves weakening of the affected muscles, and is called muscle recession. In cases of severe fibrotic changes, maximal surgical intervention - so-called deep recession - is needed. Due to the anatomical characteristics of the capsulopalpebral fascia (CPF), the main component of the lower eyelid retractors, which originates from the inferior part of the IRM belly, deep IRM recession results in lower eyelid retraction. This significantly affects both the functional state of the lower eyelid (leading to lagophthalmos) and the symmetry of the palpebral fissures. Moderate lower eyelid retraction is typically managed with retractor dissection and lateral canthoplasty, whereas in severe cases various spacers are used. To minimize the number of surgical stages, techniques have been proposed for repositioning and dissecting the Lockwood ligament, specifically the CPF head, simultaneously with IRM recession. However, the effectiveness of these methods remains debatable, and the risk of intraoperative complications is high. Further research is needed to develop an optimal surgical approach for TED patients.