title: Predicting time to refractive stability after discontinuation of rigid contact lens wear before refractive surgery.
abstract: OBJECTIVE
  To determine whether discontinuing rigid contact lenses for 3 weeks is sufficient to achieve refractive stability and if not, to identify factors, including indicators of corneal warpage, that are associated with prolonged corneal instability.
  
  
  METHODS
  University-based refractive surgery practice.
  
  
  METHODS
  Charts of patients seen for refractive surgery consultation from January 1999 to March 2001 were reviewed. Patients with a history of rigid gas-permeable (RGP) contact lens use were identified and instructed to discontinue wearing lenses 3 weeks before the initial examination. Patients were examined at 3-week intervals until a stable refraction was achieved (within +/-0.25 diopter [D] sphere and 0.25 D cylinder with less than 25 degrees of axis orientation). Visual acuity, subjective refraction, and corneal topography were obtained at each visit.
  
  
  RESULTS
  Of 55 eyes of 28 patients, 31 eyes achieved refractive stability by the second visit (early-stability group) and 24 eyes required more than 2 visits to achieve stability (late-stability group). No statistically significant between-group difference was observed in age, sex, refractive cylinder, topographic cylinder, difference between refractive and topographic cylinders, surface regularity index, surface asymmetry index, or spherical equivalent at the initial examination. The number of years of contact lens wear was significantly different between the groups (P = .05).
  
  
  CONCLUSIONS
  The time for contact lens-induced corneal changes to reach a steady state after cessation of lens wear is highly variable. Among the variables examined, including those indicating corneal warpage, the factor that correlated with the required time to refractive stability after discontinuation of RGP wear was the length of time of contact lens use. Patients who are long-term RGP wearers should be counseled that multiple visits will likely be required before a stable refraction is obtained.
authors.affiliation: Department of Ophthalmology, University of California San Francisco School of Medicine, San Francisco, CA 94143, USA.
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Tsai
authors.forename: Amgad
authors.initials: A
authors.lastname: Dowidar
authors.forename: Ayman
authors.initials: A
authors.lastname: Naseri
authors.forename: Stephen D
authors.initials: SD
authors.lastname: McLeod
mesh_terms: D000328:Adult; D003261:Contact Lenses / Q000009:adverse effects / Q000706:statistics & numerical data*; D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012029:Refraction, Ocular / Q000502:physiology; D012030:Refractive Errors / Q000209:etiology / Q000503:physiopathology*; D013997:Time Factors; D014792:Visual Acuity / Q000502:physiology; D028761:Withholding Treatment