title: Effects of Myopic Orthokeratology on Visual Performance and Optical Quality.
abstract: OBJECTIVE
  To analyze the changes in visual performance and optical quality after orthokeratology (ortho-k) treatment and its correlation with the magnitude of lens decentration and the diameter of treatment zone (TxZ).
  
  
  METHODS
  A prospective study was conducted in 27 eyes of 27 patients wearing ortho-k contact lens. Area under log contrast sensitivity function (AULCSF), modulation transfer function cutoff values (MTFcutoff), Strehl ratio (SR), and objective scattering index (OSI) were measured and compared before and 1 month after ortho-k lens treatment. Refractive sphere, astigmatism, and diameter and decentration of TxZ were tested against the change in AULCSF, MTFcutoff, SR, and OSI after ortho-k treatment in stepwise multiple linear regression models.
  
  
  RESULTS
  Objective scattering index significantly increased and AULCSF, MTFcutoff, and SR significantly decreased after ortho-k lens wear (all P<0.001). The mean TxZ diameter was 3.61±0.26 mm, and the mean magnitude of TxZ decentration was 0.60±0.16 mm. The amount of lens decentration significantly correlated with the change in AULCSF and MTFcutoff (P=0.027 and P=0.005, respectively). The diameter of TxZ significantly correlated with the change in MTFcutoff and SR (P=0.005 and P=0.024, respectively).
  
  
  CONCLUSIONS
  Visual and optical quality decreases after ortho-k treatment, which can be alleviated by a larger TxZ diameter and a smaller lens decentration.
authors.affiliation: Tianjin Medical University Eye Hospital (G.L., J.L., R.W.), Tianjin Medical University Eye Institute and Tianjin Medical University School of Optometry and Ophthalmology, Tianjin, China; Department of Cornea and Refractive Surgery (G.L., J.L., R.W.), Tianjin Medical University Eye Hospital, Tianjin, China; Department of Ophthalmology and Vision Science (Z.C., F.X., M.T., X.Z.), EYE and ENT Hospital of Fudan University, Shanghai, China; and Key Lab of Myopia (Z.C., F.X., M.T., X.Z.), Ministry of Health, Shanghai, China.
authors.forename: Guihua
authors.initials: G
authors.lastname: Liu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.forename: Feng
authors.initials: F
authors.lastname: Xue
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Mi
authors.initials: M
authors.lastname: Tian
authors.forename: Xingtao
authors.initials: X
authors.lastname: Zhou
authors.forename: Ruihua
authors.initials: R
authors.lastname: Wei
mesh_terms: D000293:Adolescent; D001251:Astigmatism / Q000503:physiopathology; D002648:Child; D003261:Contact Lenses; D015350:Contrast Sensitivity / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000628:therapy*; D054158:Orthokeratologic Procedures / Q000379:methods*; D011446:Prospective Studies; D012029:Refraction, Ocular; D012044:Regression Analysis; D014792:Visual Acuity / Q000502:physiology*