Abstract
Purpose: :
To determine whether myopic retinal defocus presented simultaneously with a clear retinal image can slow myopia progression in children.
Methods: :
Myopic defocus and a clear retinal image were created simultaneously using dual-focus (DF) soft contact lenses. DF lenses had a central correction zone 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 (same lens form but without treatment zones). Forty children, 11-14 years old with progressing myopia wore a DF lens in one randomly assigned eye and a 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). Spherical Equivalent Refraction (SER) and axial eye length (AXL) were monitored using cycloplegic autorefraction and partial coherence interferometry every 5 months. Accommodation was assessed using an open-field autorefractor.
Results: :
Visual Acuity Rating (VAR) was not significantly different with DF lenses (99.9 ± 3.5) and SVD lenses (100.2 ± 2.9: P = 0.63). Log contrast sensitivity (Pelli-Robson) was not significantly different with DF lenses (1.56 ± 0.97) and SVD lenses (1.58 ± 0.10: P = 0.21) and children accommodated normally to near targets. Myopia progression and eye elongation were significantly less in eyes wearing DF lenses than in those wearing SVD lenses. The mean treatment effects over 10 months (reductions in myopia and eye elongation) were: Period 1 = 0.252 ± 0.273 D and 0.107 ± 0.080 mm: P < 0.0001 and Period 2 = 0.204 ± 0.338 D and 0.115 ± 0.099 mm: P < 0.001). Regression analyses comparing progression in the two eyes of individual children showed that the ratio of progression with DF lenses vs progression with SVD lenses (controls) was approximately 0.55:1 for control progression rates between 0 and -1.50 D in each of the 10 month periods (Period 1 and 2).
Conclusions: :
Myopia progression and eye elongation were significantly reduced in eyes wearing DF lenses, indicating that myopic defocus presented simultaneously with a clear retinal image can slow myopia progression in children, without compromising visual function.
Clinical Trial: :
www.anzctr.org.au 12605000633684
Keywords: myopia • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • refractive error development