title: Recovery of corneal irregular astigmatism, ocular higher-order aberrations, and contrast sensitivity after discontinuation of overnight orthokeratology.
abstract: OBJECTIVE
  To examine prospectively the recovery of various parameters after discontinuation of overnight orthokeratology.
  
  
  METHODS
  Seventeen subjects undergoing orthokeratology for 12 months were examined. Refraction, corneal topography, wavefront aberrometry, a visual acuity test and a contrast sensitivity test were performed at baseline, 12 months after commencement of the procedure, and 1 week and 1 month after discontinuation of the treatment. Asymmetry and higher-order irregularity components were calculated using a Fourier analysis of the corneal topography data. Contrast sensitivity was assessed at four spatial frequencies, and the area under the log contrast sensitivity function (AULCSF) was calculated.
  
  
  RESULTS
  Orthokeratology significantly reduced manifest refraction (p<0.0001, Dunnett test) and significantly improved uncorrected visual acuity (UCVA) at 12 months after commencement of the procedure (p<0.0001). Asymmetry and higher-order irregularity components increased significantly (p<0.0001, p = 0.0032, respectively), and third- and fourth-order aberrations also increased significantly (p<0.0001). The treatment resulted in significant decreases in AULCSF (p = 0.0004). After discontinuing lens wear, all parameters, such as refraction, UCVA, asymmetry, higher-order irregularity, third-order aberration, fourth-order aberration and AULCSF, returned to the baseline level at 1 week.
  
  
  CONCLUSIONS
  This study confirmed that the effect of orthokeratology is completely reversible in light of optical quality of the eye and quality of vision as well as refraction and visual acuity.
authors.affiliation: Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki, Japan. thiraoka@md.tsukuba.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Hiraoka
authors.forename: C
authors.initials: C
authors.lastname: Okamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Ishii
authors.forename: F
authors.initials: F
authors.lastname: Okamoto
authors.forename: T
authors.initials: T
authors.lastname: Oshika
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000209:etiology*; D003261:Contact Lenses; D015350:Contrast Sensitivity; D019781:Corneal Topography; D020878:Device Removal; D006801:Humans; D009216:Myopia / Q000523:psychology / Q000628:therapy*; D054158:Orthokeratologic Procedures / Q000009:adverse effects* / Q000379:methods; D011446:Prospective Studies; D020127:Recovery of Function; D012029:Refraction, Ocular; D055815:Young Adult