Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression : a 2-year randomised clinical trial

Abstract

Aim: To determine if 'Defocus Incorporated Multiple Segments' (DIMS) spectacle lenses slow childhood myopia progression. Methods: A 2-year double-masked randomised controlled trial was carried out in 183 Chinese children aged 8-13 years, with myopia between -1.00 and -5.00 D and astigmatism <= 1.50 D. Children were randomly assigned to wear DIMS (n=93) or single vision (SV) spectacle lenses (n=90). DIMS lens incorporated multiple segments with myopic defocus of +3.50 D. Refractive error (cycloplegic autorefraction) and axial length were measured at 6month intervals. Results: 160 children completed the study, n=79 in the DIMS group and n=81 in the SV group. Average (SE) myopic progressions over 2 years were -0.41 +/- 0.06 D in the DIMS group and -0.85 +/- 0.08 D in the SV group. Mean (SE) axial elongation was 0.21 +/- 0.02 mm and 0.55 +/- 0.02 mm in the DIMS and SV groups, respectively. Myopia progressed 52% more slowly for children in the DIMS group compared with those in the SV group (mean difference -0.44 +/- 0.09 D, 95% CI -0.73 to -0.37, p<0.0001). Likewise, children in the DIMS group had less axial elongation by 62% than those in the SV group (mean difference 0.34 +/- 0.04 mm, 95% CI 0.22 to 0.37, p<0.0001). 21.5% children who wore DIMS lenses had no myopia progression over 2 years, but only 7.4% for those who wore SV lenses. Conclusions: Daily wear of the DIMS lens significantly retarded myopia progression and axial elongation in myopic children. Our results demonstrated simultaneous clear vision with constant myopic defocus can slow myopia progression.