title: Defocus Incorporated Soft Contact (DISC) lens slows myopia progression in Hong Kong Chinese schoolchildren: a 2-year randomised clinical trial.
abstract: OBJECTIVE
  To determine if 'Defocus Incorporated Soft Contact' (DISC) lens wear slows childhood myopia progression.
  
  
  METHODS
  A 2-year double-blind randomised controlled trial was carried out in 221 children aged 8-13 years, with myopia between -1.00 and -5.00 Dioptres (D) and astigmatism ≤1.00 D. Subjects were randomly assigned to the DISC (n=111) or single vision (SV; n=110) contact lens group. DISC lenses incorporated concentric rings, which provided an addition of +2.50 D, alternating with the normal distance correction. Refractive error (cycloplegic autorefraction) and axial length were measured at 6-month intervals. Differences between groups were analysed using unpaired t test.
  
  
  RESULTS
  In total, 128 children completed the study, n=65 in the DISC group and n=63 in the SV group. Myopia progressed 25% more slowly for children in the DISC group compared with those in the control group (0.30 D/year; 95% CI -0.71 to -0.47 vs 0.4 D/year; 95% CI -0.93 to -0.65, p=0.031). Likewise, there was less axial elongation for children in the DISC versus SV groups (0.13 mm/year; 95% CI 0.20 to 0.31 vs 0.18 mm/year; 95% CI 0.30 to 0.43, p=0.009). Treatment effect correlated positively with DISC lens wearing time (r=0.342; p=0.005). Indeed, myopia in children who wore the DISC lenses for five or more hours/day progressed 46% (mean difference=-0.382 D, p=0.001; 95% CI -0.59 to -0.17) less than those in the SV group.
  
  
  CONCLUSIONS
  The daily wearing of DISC lens significantly slowed myopia progression and axial elongation in Hong Kong schoolchildren. The findings demonstrated that simultaneous clear vision with constant myopic defocus can retard myopia progression.
authors.affiliation: Centre for Myopia Research, School of Optometry, The Hong Kong Polytechnic University, , Hung Hom, Kowloon, Hong Kong.
authors.forename: Carly Siu Yin
authors.initials: CS
authors.lastname: Lam
authors.forename: Wing Chun
authors.initials: WC
authors.lastname: Tang
authors.forename: Dennis Yan-Yin
authors.initials: DY
authors.lastname: Tse
authors.forename: Ying Yung
authors.initials: YY
authors.lastname: Tang
authors.forename: Chi Ho
authors.initials: CH
authors.lastname: To
mesh_terms: D000293:Adolescent; D058452:Axial Length, Eye / Q000502:physiology; D002648:Child; D003263:Contact Lenses, Hydrophilic; D018450:Disease Progression; D004311:Double-Blind Method; D005260:Female; D006723:Hong Kong; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000517:prevention & control*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology
keywords: Child Health (Paediatrics); Clinical Trial; Contact Lens; Optics and Refraction