title: RK4 (reverse-geometry) contact lens fitting after penetrating keratoplasty.
abstract: OBJECTIVE
  We evaluated the performance of the RK4 (reverse-geometry) contact lens in patients with flat central and steep peripheral corneal topography after penetrating keratoplasty (PK).
  
  
  METHODS
  A retrospective study was performed of post-PK patients fitted with RK4 lenses on the Cornea Service at Wills Eye Hospital, between March 2000 and February 2002.
  
  
  RESULTS
  Fifteen eyes of 13 post-PK patients were fitted with RK4 lenses and monitored for more than two months (range, 2.1-23.5 months; mean, 8.1 +/- 7.0 months). The average number of lens refits per eye was 1.0 +/- 1.2 (range, 0-4). Ninety-three percent (14/15) of the eyes that were fitted achieved at least 20/30 visual acuity, and 53% (8/15) of eyes achieved 20/20 visual acuity. A comparison of prefitted and post-fitted corrected visual acuity demonstrated a statistically significant improvement (P < 0.01). RK4 lenses were successfully worn full time or part time in all cases.
  
  
  CONCLUSIONS
  The RK4 lens can provide well-tolerated visual correction in cases with central flat, peripheral steep corneal contour following PK.
authors.affiliation: Cornea Service, Wills Eye Hospital, Philadelphia, PA 19107, USA.
authors.forename: Jen-Chieh
authors.initials: JC
authors.lastname: Lin
authors.forename: Elisabeth J
authors.initials: EJ
authors.lastname: Cohen
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Rapuano
authors.forename: Peter R
authors.initials: PR
authors.lastname: Laibson
mesh_terms: D000328:Adult; D000368:Aged; D003261:Contact Lenses; D003315:Cornea / Q000601:surgery; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000601:surgery; D015948:Keratoplasty, Penetrating; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D017755:Prosthesis Fitting; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity