title: Effect of dual-focus soft contact lens wear on axial myopia progression in children.
abstract: OBJECTIVE
  To test the efficacy of an experimental Dual-Focus (DF) soft contact lens in reducing myopia progression.
  
  
  METHODS
  Prospective, randomized, paired-eye control, investigator-masked trial with cross-over.
  
  
  METHODS
  Forty children, 11-14 years old, with mean spherical equivalent refraction (SER) of -2.71 ± 1.10 diopters (D).
  
  
  METHODS
  Dual-Focus lenses had a central zone that corrected refractive error and concentric treatment zones that created 2.00 D of simultaneous myopic retinal defocus during distance and near viewing. Control was a single vision distance (SVD) lens with the same parameters but without treatment zones. Children wore a DF lens in 1 randomly assigned eye and an SVD lens in the fellow eye for 10 months (period 1). Lens assignment was then swapped between eyes, and lenses were worn for a further 10 months (period 2).
  
  
  METHODS
  Primary outcome was change in SER measured by cycloplegic autorefraction over 10 months. Secondary outcome was a change in axial eye length (AXL) measured by partial coherence interferometry over 10 months. Accommodation wearing DF lenses was assessed using an open-field autorefractor.
  
  
  RESULTS
  In period 1, the mean change in SER with DF lenses (-0.44 ± 0.33 D) was less than with SVD lenses (-0.69 ± 0.38 D; P < 0.001); mean increase in AXL was also less with DF lenses (0.11 ± 0.09 mm) than with SVD lenses (0.22 ± 0.10 mm; P < 0.001). In 70% of the children, myopia progression was reduced by 30% or more in the eye wearing the DF lens relative to that wearing the SVD lens. Similar reductions in myopia progression and axial eye elongation were also observed with DF lens wear during period 2. Visual acuity and contrast sensitivity with DF lenses were not significantly different than with SVD lenses. Accommodation to a target at 40 cm was driven through the central distance-correction zone of the DF lens.
  
  
  CONCLUSIONS
  Dual-Focus lenses provided normal acuity and contrast sensitivity and allowed accommodation to near targets. Myopia progression and eye elongation were reduced significantly in eyes wearing DF lenses. The data suggest that sustained myopic defocus, even when presented to the retina simultaneously with a clear image, can act to slow myopia progression without compromising visual function.
  
  
  BACKGROUND
  Proprietary or commercial disclosure may be found after the references.
authors.affiliation: Department of Optometry and Vision Science, New Zealand National Eye Centre, The University of Auckland, New Zealand.
authors.forename: Nicola S
authors.initials: NS
authors.lastname: Anstice
authors.forename: John R
authors.initials: JR
authors.lastname: Phillips
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D000293:Adolescent; D002648:Child; D003263:Contact Lenses, Hydrophilic; D018592:Cross-Over Studies; D018450:Disease Progression; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000628:therapy*; D011446:Prospective Studies; D012029:Refraction, Ocular; D016896:Treatment Outcome; D014792:Visual Acuity