title: Empirical advanced orthokeratology through corneal topography: the University of Houston clinical study.
abstract: OBJECTIVE
  Traditionally, orthokeratology has used diagnostic lenses to determine the best fit. The purpose of this study was to determine the efficacy of fitting empirically from corneal topography, without the use of diagnostic lenses.
  
  
  METHODS
  Twenty-nine subjects, 18 to 37 years old, with myopia of 1.00 to 4.00 diopters (D) and astigmatism of no more than 1.50 D, were entered into this 6-month study. Corneal topography, scanning slit topography and corneal thickness (Orbscan), confocal microscopy, ultrasound corneal thickness, aberrometry, and biomicroscopy were used to assess corneal changes. Unaided logMAR high-contrast visual acuity, subjective refraction, and questionnaires were used to monitor vision and symptoms. Follow-up visits were scheduled after 1 day, 1 week, 2 weeks, 1 month, 3 months, and 6 months.
  
  
  RESULTS
  For 6-month data, unaided logMAR acuity improved from 0.78 +/- 0.26 in the right eye and 0.75 +/- 0.22 in the left eye to 0.06 +/- 0.18 in the right eye and 0.04 +/- 0.16 in the left eye. Myopia decreased from -2.55 +/- 0.87 D in the right eye and -2.47 +/- 0.89 D in the left eye to +0.45 +/- 0.74 D in the right eye and -0.17 +/- 0.69 D in the left eye. Shape factor, using corneal topography, increased from 0.85 +/- 0.13 in the right eye and 0.85 +/- 0.15 in the left eye to 1.28 +/- 0.32 in the right eye and 1.30 +/- 0.29 in the left eye. Both eyes showed a decrease in lower-order aberrations (i.e., defocus) and an increase in higher-order aberrations (i.e., spherical aberrations and coma).
  
  
  CONCLUSIONS
  Myopia reduction after 1 week was clinically insignificant from the 1-month results, indicating that the full effect is achieved by 1 week. Neither total nor epithelial corneal thickness varied significantly from baseline measurements.
authors.affiliation: Eye Care Associates, 5320 Richmond Ave, Houston, TX 77056, USA. selhage1@aol.com
authors.forename: Sami
authors.initials: S
authors.lastname: El Hage
authors.forename: Norman E
authors.initials: NE
authors.lastname: Leach
authors.forename: William
authors.initials: W
authors.lastname: Miller
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Prager
authors.forename: Jason
authors.initials: J
authors.lastname: Marsack
authors.forename: Katrina
authors.initials: K
authors.lastname: Parker
authors.forename: Angela
authors.initials: A
authors.lastname: Minavi
authors.forename: Amber
authors.initials: A
authors.lastname: Gaume
mesh_terms: D000328:Adult; D003261:Contact Lenses; D019781:Corneal Topography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000628:therapy*; D017755:Prosthesis Fitting / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity