title: Age and gender-specific reference values of orbital fat and muscle volumes in Caucasians.
abstract: OBJECTIVE
  To provide age and gender-specific reference values for orbital fat and muscle volumes (MV) in Caucasian adults.
  
  
  METHODS
  Computed tomographic scans of 160 orbits from 52 men and 55 women, aged 20-80 years, not affected by orbital disease were evaluated. Orbital bony cavity volume (OV), fat volume (FV) and MV were calculated by a previously validated method using the software program Mimics. Ratios of FV to OV and of MV to OV were determined.
  
  
  RESULTS
  OV, FV and MV were all significantly larger in men than in women (p<0.001), but FV/OV and MV/OV were similar in both sexes. OV and MV did not change with age, but FV increased with advancing age in both women (p<0.001) and men (p<0.001). Linear regression analysis with FV/OV and MV/OV ratios as dependent variables and age and gender as independent variables showed a significant correlation between age and FV/OV (r=0.52, p<0.0001) and age and MV/OV (r=-0.26, p=0.001).
  
  
  CONCLUSIONS
  Advancing age is associated with an increase of FV/OV and a minor decrease of MV/OV. Gender-specific differences in orbital FV and MV disappear once FV and MV are related to OV, by calculating the ratios FV/OV and MV/OV. Age-specific gender-neutral reference ranges (2.5 and 97.5 percentiles) of FV/OV and MV/OV are presented.
authors: Orbital Centre, Department of Ophthalmology, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. n.i.regensburg@amc.nl
authors: Noortje I
authors: NI
authors: Regensburg
authors: Wilmar M
authors: WM
authors: Wiersinga
authors: Mirjam E J
authors: ME
authors: van Velthoven
authors: Tos T J M
authors: TT
authors: Berendschot
authors: Frans W
authors: FW
authors: Zonneveld
authors: Lelio
authors: L
authors: Baldeschi
authors: Peerooz
authors: P
authors: Saeed
authors: Maarten P
authors: MP
authors: Mourits
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D050218:Body Fat Distribution; D005260:Female; D006801:Humans; D016014:Linear Models; D050356:Lipid Metabolism; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D009915:Orbit / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D009929:Organ Size; D012016:Reference Values; D015203:Reproducibility of Results; D017678:Sex Distribution; D014057:Tomography, X-Ray Computed; D044465:White People; D055815:Young Adult