Quantification of Extraocular Muscles (EOMs) in normals and patients with graves' orbitopathy in different positions of coronal CT scans

M. C.B. Tasso, A. A.V. Cruz

Research output: Contribution to journalArticle

Abstract

Purpose. The aim of this study was to quantify EOMs widths from coronal CT scans in different positions along the antero-posterior orbital axis in controls and patients with Graves' orbitopathy. Methods. EOMs widths were measured from coronal CT scans (3mm slices) of two groups of subjects: controls (n = 70) and patients with Graves' orbitopathy (n = 41). None of the Graves' patients presented with diplopia or optical neuropathy. All EOMs measurements were done at the same six positions: 3, 6, 9, 12, 15 and 18 mm behind the lateral orbital rim (P3, P6, P9, P12, P15 and P18). Multi factor ANOVA (muscle, position and group) was used to compare the data from both groups. Results. All three factors (group, position and muscle) as well as the interactions muscle vs position and group vs position were significant. The horizontal recti were thinner than the vertical recti and, as expected, the EOMs from the Graves' patients were larger. For the control group, the width of the EOMs at P6, P9 and P12 were equal and larger than at P3, P15 and P18. For the Graves' patients, only the width of the EOMs at P15 and P18 were thinner than at the other positions. For both groups, the lateral rectus was significantly thinner than the other muscles at P3 .Conclusions. In controls, the width of the EOMs differ along the antero-posterior orbital axis because the muscles are fusiform. Coronal CT slices at 6, 9 and 12 mm behind the lateral orbital rim cut the belly of the EOMs and so these slices display the largest EOMs dimensions. At P3, the lateral rectus muscle is thinner. The relationship between muscle width and position was modified in the Graves' patients.

Original languageEnglish (US)
Pages (from-to)S156
JournalInvestigative Ophthalmology and Visual Science
Volume37
Issue number3
StatePublished - Feb 15 1996

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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