title: Decrease in intraocular pressure following orthokeratology measured with a noncontact tonometer.
abstract: OBJECTIVE
  Orthokeratology for correction of myopia reduces corneal power by flattening corneal curvature and thinning central corneal thickness (CCT). Measurement of intraocular pressure (IOP) with a noncontact tonometer is known to be affected by CCT and corneal curvature. We investigated the influence of orthokeratology on such measurements of IOP.
  
  
  METHODS
  This was a prospective, interventional case series derived from a clinical trial of orthokeratology lenses in two hospitals. Both eyes of 45 subjects were fitted with reverse-geometry lenses, worn for more than 4 h overnight for 52 weeks. Uncorrected visual acuity, refraction, IOP (with a noncontact tonometer), CCT, and corneal curvature were measured.
  
  
  RESULTS
  Uncorrected visual acuity, spherical equivalent value, IOP, CCT, and the radius of corneal curvature were 0.93 ± 0.27, -2.87 ± 1.05 D, 13.5 ± 2.5 mmHg, 536.2 ± 39.6 μm, and 7.88 ± 0.25 mm, respectively, before orthokeratology, and 0.17 ± 0.34, -1.05 ± 1.18 D, 12.4 ± 2.7 mmHg, 528.6 ± 40.8 μm, and 8.10 ± 0.31 mm at 52 weeks after treatment. The changes in all parameters were significant, and the change in IOP was significantly correlated with that in CCT at 24 weeks and thereafter.
  
  
  CONCLUSIONS
  Orthokeratology for myopia leads to a decrease in IOP measured with a noncontact tonometer, likely as a result of the associated decrease in CCT.
authors.affiliation: Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Ishida
authors.affiliation: Department of Ocular Pathophysiology, Yamaguchi University School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi, 755-8505, Japan. yanai@yamaguchi-u.ac.jp.
authors.forename: Ryoji
authors.initials: R
authors.lastname: Yanai
authors.affiliation: Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sagara
authors.affiliation: Department of Ophthalmology, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi, 755-8505, Japan.|Department of Ocular Pathophysiology, Yamaguchi University School of Medicine, 1-1-1 Minami-Kogushi, Ube, Yamaguchi, 755-8505, Japan.
authors.forename: Teruo
authors.initials: T
authors.lastname: Nishida
authors.affiliation: Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, 113-8431, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Toshida
authors.affiliation: Department of Ophthalmology, Juntendo University School of Medicine, Tokyo, 113-8431, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Murakami
mesh_terms: D000328:Adult; D003261:Contact Lenses; D003315:Cornea / Q000473:pathology; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000628:therapy*; D054158:Orthokeratologic Procedures; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D014065:Tonometry, Ocular; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult