title: Reversibility of effects of orthokeratology on visual acuity, refractive error, corneal topography, and contrast sensitivity.
abstract: OBJECTIVE
  To investigate the changes in corneal shape and optical performance during and after discontinuation of overnight orthokeratology for correction of myopia.
  
  
  METHODS
  Both eyes of 15 subjects were fitted with overnight reverse-geometry orthokeratology lenses, which were then worn for >4 hr overnight for 52 weeks. Subjects were free of ocular disease and had a corrected visual acuity of > or =1.0. Refractive correction, uncorrected visual acuity, corneal topography, and contrast sensitivity (at 4 spatial frequencies) were measured under photopic conditions.
  
  
  RESULTS
  Refractive error (spherical equivalent) and contrast sensitivity were decreased, whereas uncorrected visual acuity, the surface asymmetry index, and the surface regularity index were increased, 1 week after the onset of overnight orthokeratology and remained so during the 52 weeks of treatment. These parameters had largely returned to baseline values by 8 weeks after treatment discontinuation.
  
  
  CONCLUSIONS
  Overnight orthokeratology improved uncorrected visual acuity and reduced refractive error but increased corneal irregularity and impaired contrast sensitivity. However, these changes in visual function and corneal shape were reversed after discontinuation of orthokeratology lens wear.
authors.affiliation: Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube City, Yamaguchi, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Ryoji
authors.initials: R
authors.lastname: Yanai
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Chikamoto
authors.forename: Tai-Ichiro
authors.initials: T
authors.lastname: Chikama
authors.forename: Kiichi
authors.initials: K
authors.lastname: Ueda
authors.forename: Teruo
authors.initials: T
authors.lastname: Nishida
mesh_terms: D000328:Adult; D003261:Contact Lenses; D015350:Contrast Sensitivity / Q000502:physiology*; D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology* / Q000628:therapy*; D054158:Orthokeratologic Procedures; D011446:Prospective Studies; D014792:Visual Acuity / Q000502:physiology*