title: Computed tomography measurement of extra-ocular muscle diameters in a population of normal patients in a tertiary hospital in Nigeria.
abstract: BACKGROUND
  Measurements of extraocular muscle diameter may be useful in diagnosis and as an outcome indicator in the assessment of treatment options in thyroid-associated ophthalmopathy. Racial differences are known to account for craniofacial variations and orbital sizes.
  
  
  OBJECTIVE
  To determine the normal diameters of extra-ocular muscles using computed tomography in a homogeneous, group of hospital patients in a tertiary hospital in Nigeria.
  
  
  METHODS
  The maximum diameters of extra-ocular muscles were measured for 182 normal patients on thin slice reconstructed coronal computed tomography images. The effects of age and sex were determined.
  
  
  RESULTS
  Normal ranges for the diameters (mean + 2 SDs) of extraocular muscles were 4.5 + 1.2 mm for medial rectus, 4.9 + 2.1 mm for lateral rectus, 4.8 + 1.6 mm for inferior rectus and 4.0 + 1.5 mm for the superior group. The mean diameter of the extra-ocular muscles of male patients was not significantly larger than that of female patients (p > 0.05). There was a small but positive correlation between age and diameter of each extra-ocular muscle except in the left medial rectus and right lateral rectus muscles (P < 0.05).
  
  
  CONCLUSIONS
  These normative values may serve as radiological reference values in the assessment of changes in size and suspected enlargement of the extraocular muscles in Nigerian patients. They may also be extrapolated to other Black African patients, until population studies become available.
authors.forename: G I
authors.initials: GI
authors.lastname: Ogbole
authors.forename: O A
authors.initials: OA
authors.lastname: Ogun
authors.forename: D
authors.initials: D
authors.lastname: Olusumade
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D049970:Graves Ophthalmopathy / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009549:Nigeria; D009801:Oculomotor Muscles / Q000000981:diagnostic imaging / Q000502:physiology; D012016:Reference Values; D062606:Tertiary Care Centers; D014057:Tomography, X-Ray Computed / Q000379:methods