title: An observational cross-sectional study on the corneal endothelium of medium-term rigid gas permeable contact lens wearers.
abstract: OBJECTIVE
  To assess if polymegethism and pleomorphism were evident in corneal endothelium after medium-term rigid gas permeable (RGP) contact lens wear.
  
  
  METHODS
  In a cross-sectional observational study over 12 years, single images of the central region of the corneal endothelium of one eye of 46 subjects were taken with a non-contact specular microscope, along with a measure of central corneal thickness (CCT). The images were printed onto A3-sized paper and 100 cells/image measured by planimetry.
  
  
  RESULTS
  Subjects aged between 20 and 32 years, with an average cumulative RGP wear of 6.0+/- 1.6 years (range 3-9 years) were assessed; 26 of the subjects were Caucasian and 20 were Asian. The mean CCT was 0.515+/- 0.027mm. The group cell area value was 401+/- 42 sq micron to give an estimated endothelial cell density (ECD) of 2520+/- 273 cells/sq mm. As compared to a historical database, most endothelia (37/46) showed some changes with the mean coefficient of variation on cell area (COV) being 36.7+/- 8.0% and the percentage of 6-sided (HEX) being 51.8+/- 8.8%. There were modest correlations between years of RGP wear and both COV (p=0.009, r spearman=0.424) and HEX (p=0.025, r spearman=-0.291), but not for ECD or CCT.
  
  
  CONCLUSIONS
  Corneal endothelial polymegethism appears to be a commonplace consequence of RGP lens wear with the magnitude of the change being related to the cumulative duration of the lens wear.
authors.affiliation: Glasgow-Caledonian University, Department of Vision Sciences, Cowcaddens Road, Glasgow G4 OBA, United Kingdom. Electronic address: m.doughty@gcal.ac.uk.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Doughty
mesh_terms: D000328:Adult; D002452:Cell Count; D048430:Cell Shape; D048429:Cell Size; D003261:Contact Lenses / Q000009:adverse effects* / Q000706:statistics & numerical data; D055954:Corneal Endothelial Cell Loss / Q000175:diagnosis / Q000209:etiology*; D063171:Corneal Pachymetry; D003430:Cross-Sectional Studies; D004728:Endothelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008853:Microscopy; D055815:Young Adult
keywords: Cell pleomorphism; Corneal endothelium; Human; Polymegethism; RGP lens wear