title: Determination of microdot stromal degenerations within corneas of long-term contact lens wearers by confocal microscopy.
abstract: OBJECTIVE
  To ascertain whether a relationship exists between the presence of microdot deposits within the corneal stroma of long-term contact lens wearers as seen by confocal microscopy and the contact lens wear time, material, or other patient variables.
  
  
  METHODS
  Thirty-six myopic patients with a 15- to 43-year history of hard, rigid gas-permeable, or soft hydrogel contact lens wear and 12 age-matched emmetropic or spectacle-corrected myopic volunteers were included in this study. The numerical density and size of microdot deposits within the anterior, mid, and posterior stroma were determined with the confocal microscope, and the data were subjected to multiple regression statistical analysis.
  
  
  RESULTS
  Microdot deposits were encountered throughout the entire depth of the corneal stroma in all contact lens wearers. None of the control subjects showed microdot deposits. The numerical densities and the size range of microdots were similar in each of the stromal layers (anterior, mid, and posterior), with total mean values (+/- SD) for each parameter being 65.1 x 10(3) +/- 26.9 x 10(3) dots/mm (range, 21.4 x 10(3) to 121.1 x 10(3) dots/mm) and 3.04 +/- 0.92 microm (range, 1.5-5.0 microm), respectively.
  
  
  CONCLUSIONS
  Microdot deposits may represent granules of lipofuscinlike material within the corneal stroma of long-term contact lens wearers, formed as a result of chronic oxygen deprivation and chronic microtrauma to the cornea. No one in the control group showed microdot deposits. Among the independent variables, soft contact lens wear time had the most profound influence on numerical microdot density and size in our statistical equations.
authors.affiliation: Department of Ophthalmology (P.T., R.C., G-M.S., B.E.F.), University of Bern, Inselspital, CH-3010 Bern, Switzerland. peter.trittibach@insel.ch
authors.forename: Peter
authors.initials: P
authors.lastname: Trittibach
authors.forename: Robin
authors.initials: R
authors.lastname: Cadez
authors.forename: Raphael
authors.initials: R
authors.lastname: Eschmann
authors.forename: Gian-Marco
authors.initials: GM
authors.lastname: Sarra
authors.forename: Matthias
authors.initials: M
authors.lastname: Boehnke
authors.forename: Beatrice E
authors.initials: BE
authors.lastname: Frueh
mesh_terms: D000328:Adult; D000368:Aged; D003261:Contact Lenses / Q000009:adverse effects*; D003316:Corneal Diseases / Q000175:diagnosis* / Q000209:etiology*; D003319:Corneal Stroma / Q000473:pathology*; D005260:Female; D006801:Humans; D008134:Long-Term Care; D008297:Male; D018613:Microscopy, Confocal / Q000379:methods; D008875:Middle Aged; D009216:Myopia / Q000628:therapy