title: Effect of progressive addition lenses on myopia progression in Japanese children: a prospective, randomized, double-masked, crossover trial.
abstract: OBJECTIVE
  This prospective, randomized, double-masked, crossover trial was conducted to evaluate the clinical effectiveness of progressive addition lenses (PALs) compared with single-vision lenses (SVLs) on myopia progression in Japanese children.
  
  
  METHODS
  Ninety-two children fulfilling the inclusion criteria (age: 6-12 years, spherical equivalent refractive errors: -1.25 to -6.00 D) were randomly allocated to either 18 months of wearing PALs (near addition: +1.50 D) followed by 18 months of SVLs (group 1), or 18 months of wearing SVLs followed by 18 months of wearing PALs (group 2), and were followed up for 3 years (two-stage crossover design). The primary outcome measure was myopia progression, as determined by cycloplegic autorefraction.
  
  
  RESULTS
  Eighty-six (93%) children completed both treatment periods. A mixed-model, two-way analysis of variance (ANOVA) performed using 3-year data identified a significant treatment effect of PALs compared with SVLs (P = 0.0007), with a mean 18-month difference of 0.17 D (95% CI: 0.07-0.26 D). This analysis also indicated a significant period effect (P = 0.0040) and a significant treatment-by-period interaction (P = 0.0223): Group 1 showed a slower myopia progression than did group 2.
  
  
  CONCLUSIONS
  The use of PALs slowed myopia progression, although the treatment effect was small, as previously reported in ethnically diverse children in the United States. The significant treatment-by-period interaction suggests that early application of PALs would probably be more beneficial for these age and refraction ranges (isrctn.org number, 28611140).
authors.affiliation: Department of Ophthalmology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan. shasebe@md.okayama-u.ac.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hasebe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohtsuki
authors.forename: Takafumi
authors.initials: T
authors.lastname: Nonaka
authors.forename: Chiaki
authors.initials: C
authors.lastname: Nakatsuka
authors.forename: Manabu
authors.initials: M
authors.lastname: Miyata
authors.forename: Ichiro
authors.initials: I
authors.lastname: Hamasaki
authors.forename: Shuhei
authors.initials: S
authors.lastname: Kimura
mesh_terms: D044466:Asian People; D002648:Child; D018592:Cross-Over Studies; D018450:Disease Progression; D004311:Double-Blind Method; D004867:Equipment Design; D005139:Eyeglasses; D005260:Female; D006801:Humans; D008297:Male; D009216:Myopia / Q000208:ethnology / Q000503:physiopathology* / Q000534:rehabilitation*; D010349:Patient Compliance; D012029:Refraction, Ocular; D011795:Surveys and Questionnaires; D016896:Treatment Outcome