title: Clinical experience with piggyback contact lens systems on keratoconic eyes.
abstract: BACKGROUND
  A piggyback contact lens system (PBCLS) is used when traditional lenses do not provide optimal vision or tolerance. This study assessed the use of PBCLS in keratoconic patients.
  
  
  METHODS
  The charts of 205 keratoconic patients were retrospectively reviewed and 16 patients wearing PBCLS were identified. Visual acuity, average wearing time, and ocular complication data with PBCLS were analyzed.
  
  
  RESULTS
  Vision and average lens wearing time were stable, if not improved, for the 16 patients when the data was compared to the patients' wear of rigid gas permeable contact lenses. Although two patients developed neovascularization and one patient developed giant papillary conjunctivitis, all pre-existing corneal complications resolved with PBCLS wear. Average Dk/L through the center and mid-periphery of the PBCLS were 8.4 +/- 1.2 x 10(-9) (mean +/- standard deviation) and 4.5 +/- 1.8 x 10(-9) cm2ml O2/sec ml mmHg (mean +/- standard deviation) respectively. No gross corneal edema was noted upon slit lamp observation.
  
  
  CONCLUSIONS
  PBCLS can be beneficial in the management of keratoconus.
mesh_terms: D000328:Adult; D003261:Contact Lenses / Q000009:adverse effects; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D017755:Prosthesis Fitting / Q000379:methods; D012189:Retrospective Studies; D014792:Visual Acuity