Ocular dysmotility associated with extraocular muscle volume, density
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Key takeaways:
- Increased volume and decreased density of extraocular muscles were linked with ocular dysmotility in patients with thyroid eye disease.
- EOM volumes may be clinically useful for evaluating motility restrictions.
Ocular dysmotility in thyroid eye disease was significantly associated with increased total volume and decreased total density of extraocular muscles, according to a presentation at Real World Ophthalmology.
“Thyroid eye disease (TED) can lead to restrictive extraocular myopathy, in which swelling or fibrosis causes the extraocular muscles (EOM) to become limited in their movement, preventing the opposing action of the antagonist muscle,” Joyce Wen and colleagues wrote in a poster presentation.
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They sought to determine the relationship between EOM size and ocular dysmotility through volumetric and density analysis. In the retrospective chart review, the CT orbit scans of 31 patients with TED were manually segmented to determine the volume and density of EOM and orbital fat. Extraocular movement exams determined dysmotility on a scale of –4 to 4, with 0 indicating normal full movement, –1 to –4 indicating decreased movement and +1 to +4 indicating increased movement.
Both increased mean total EOM volume and decreased mean total EOM density were associated with dysmotility in any extraocular movement direction (P = .017 and P = .049, respectively).
The most frequent finding was decreased adduction/elevation movement (45.2%), followed by abduction/elevation (41.9%) and abduction (41.9%). Additionally, there was a correlation between reduced abduction/elevation and increased inferior rectus volume (P = .029), as well as between reduced abduction and increased medial rectus volume (P < .001).
“There were no correlations between individual EOM densities and motility restrictions,” according to the authors.
“EOM volumes may provide clinically useful information in evaluating EOM motility restriction for TED patients,” they wrote. “Likewise, EOM dysmotility elicited on exam may predict changes in EOM volume.”
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Wen J, et al. Ocular dysmotility in thyroid eye disease: A volumetric and density analysis. Presented at: Real World Ophthalmology; April 15, 2023 (virtual meeting).
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