title: The long-term effects of polymethylmethacrylate contact lens wear on the corneal endothelium.
abstract: OBJECTIVE
  The purpose of this study is to determine the long-term effects of polymethylmethacrylate (PMMA) contact lens wear on the corneal endothelium. The authors had noted previously advanced polymegethism and decreased cell densities in a few long-term PMMA contact lens wearers. They evaluated a large group of such lens wearers to determine the prevalence of polymegethism and reduced endothelial cell density within this lens-wearing population.
  
  
  METHODS
  The authors examined the morphologic characteristics of the corneal endothelium in 162 PMMA contact lens wearers or age-matched controls. Eighty-one subjects had worn contact lenses for more than 20 years.
  
  
  RESULTS
  Patients showed advanced polymegethism and pleomorphism compared with controls. Mean cell density in the contact lens-wearing group was not different from controls, but a significantly greater percentage of contact lens wearers (11%, 9 of 81 patients) had cell densities less than 2000 cells/mm2 compared with controls (2.5%, 2 of 81 patients), and were also significantly more likely to have severe polymegethism (coefficient of variation, > 0.60) and severe pleomorphism (frequency of hexagons < 40%).
  
  
  CONCLUSIONS
  This study is unique, in that it notes a subgroup of PMMA contact lens wearers who are more susceptible to significant morphometric changes and reduced endothelial cell densities with long-term contact lens use.
authors.affiliation: Casey Eye Institute, Corneal and External Disease Service, Oregon Health Sciences University, Portland 97201-4197.
authors.forename: S M
authors.initials: SM
authors.lastname: MacRae
authors.forename: M
authors.initials: M
authors.lastname: Matsuda
authors.forename: D S
authors.initials: DS
authors.lastname: Phillips
mesh_terms: D000328:Adult; D000368:Aged; D002452:Cell Count; D003261:Contact Lenses / Q000009:adverse effects*; D003316:Corneal Diseases / Q000209:etiology / Q000473:pathology; D004728:Endothelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D020366:Methylmethacrylate; D008768:Methylmethacrylates; D008853:Microscopy; D008875:Middle Aged; D015995:Prevalence
chemical_list: D008768:Methylmethacrylates; D020366:Methylmethacrylate