Quantification of Extraocular Muscles (EOMs) from coronal CT scans of different subtypes of graves' orbitopathy

F. C. Guimarães, P. A.D. Rubin, A. A.V. Cruz

Research output: Contribution to journalArticlepeer-review


Optic neuropathy in Graves' disease has been related to EOM involvement. However, comparisons of EOMs size in different subtypes of Graves' orbitopathy has not been reported in the literature. Purpose. To quantify EOMs from coronal CT scans of different types of orbital involvement in Graves' disease. Methods. Coronal CT scans from 40 orbits/20 patients with Graves' disease were retrospectively reviewed. The orbits were classified in 3 groups: a) only proptosis (group 1), b) proptosis and restrictive squint (group 2), and c) proptosis, restrictive squint and optic neuropathy (group 3). Coronal CT scans from 15 orbits/ 15 controls were also examined (group 4). The width of the EOMs were measured at the same coronal position, 9 mm behind the lateral orbital rim. A multi factor ANOVA (muscle and group) was used to compare the data. Results. Both factors were significant: group (F=35.7999, p<0.0000) and muscle (F=2.683, p=0.0481). Multiple range analysis (Newman-Keuls) showed that the largest EOMs was found in the group 3 (optic neuropathy). EOMs from groups 1 and 2 were not different between them and larger than EOMs from group 4. The inferior rectus was the largest muscle and the lateral rectus the smallest one. The interaction muscle > group was not significant. Conclusions. Our data show that all EOMs are more affected in optic neuropathy than in the other subtypes of Graves' orbitopathy. EOMs from patients with restrictive squint without optic neuropathy were not larger than EOMs from patients with only proptosis. The inferior rectus muscle tends to be the largest muscle in all Graves' groups, but this effect is much more evident for the patients with optic neuropathy.

Original languageEnglish (US)
Pages (from-to)S157
JournalInvestigative Ophthalmology and Visual Science
Issue number3
StatePublished - Feb 15 1996

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience


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