Fibrotic bands in thyroid eye disease: a contributing factor to persistent postoperative restriction

Accessory extraocular fibrous bands are orbital structures that are typically symptomatic in patients with congenital cranial dysinnervation disorders. However, orbital imaging studies have documented asymptomatic accessory extraocular fibrous in individuals without strabismus. The role of preexisting symptomatic fibrotic bands in causing persistent restrictive strabismus in patients with acquired strabismus and the possibility that inflammatory conditions affecting the extraocular muscles could also affect those bands is rarely discussed. We present 2 cases of thyroid eye disease (TED) in which asymptomatic bands likely became clinically significant with progression of TED. Both patients developed restrictive strabismus and underwent strabismus surgery. Both showed persistent positive forced duction tests (FDT) despite muscle disinsertion. Intraoperative identification and excision of fibrotic bands led to normalization of the FDT and improved surgical outcomes. These bands may contribute to atypical motility patterns in TED.