April 1, 2021
By Dwight Akerman, OD, MBA, FAAO
The Hoya MiyoSmart spectacle lens with DIMS technology is designed to control myopia in children, based on the principle of myopic defocus and simultaneous vision. It is a dual-focus spectacle lens consisting of a 9 mm central optical zone for correcting distance refractive error and about 400 tiny circular segments with a relative positive power of 3.50D equally distributed throughout the mid-peripheral area in a honeycomb pattern.
In 2020, Lam and co-researchers from The Hong Kong Polytechnic University published data from a two-year double-masked randomized controlled trial (RCT.) Chinese schoolchildren wearing DIMS spectacle lenses had myopia progression significantly reduced by 59%, and axial elongation decreased by 60% compared with those wearing single vision (SV) lenses.
The newly published study aims to determine (1) if myopia retardation, as measured by changes in spherical equivalent refraction (SER) and axial length (AL), continues in the third year of DIMS spectacle lens wear and (2) if myopia retardation is exhibited in the first year of DIMS wear by the original SV control group. Both groups were compared with a new historical control group. Ethnic Chinese children who had completed the two-year RCT were invited to participate in the third-year follow-up study.
Myopia progression and axial elongation were less in the subjects wearing DIMS lenses throughout the three years, first compared with the initial control group (which subsequently became the Control-to-DIMS group), and then in the last 12 months compared with the historical control group. In the DIMS group, myopia progression and axial elongation in the third year were similar to those in the first and second years.
The mean changes in SER and AL in the DIMS treatment group over the three years were −0.52±0.69D and 0.31±0.26 mm. These findings are comparable with the corresponding results in the three-year RCT trial with dual power soft contact lenses by Chamberlain et al. (-0.51±0.64D and 0.30±0.27 mm.)
The Control-to-DIMS group subjects showed significant reductions in myopia progression and axial elongation after switching from SV to DIMS lens wear. Their SER and AL changes in the third year were comparable to the first-year changes in the DIMS group, even though these subjects were two years older. In comparison to the historical control group, their myopia progression and axial elongation in the third year, after adjustment, were reduced by 86% and 61%, respectively.
The researchers concluded that the DIMS spectacle lens slowed myopia progression and axial elongation in children throughout the three years of study. The myopia control effect was also demonstrated in the Control-to-DIMS group. These findings provided further evidence that DIMS spectacle lenses slowed myopia progression and axial elongation in children.
Myopia control effect of defocus incorporated multiple segments (DIMS) spectacle lens in Chinese children: results of a 3-year follow-up study
Carly SY Lam, Wing Chun Tang, Paul H Lee, Han Yu Zhang, Hua Qi, Keigo Hasegawa, Chi Ho To
Aims: To determine myopia progression in children who continued to wear the defocus incorporated multiple segments (DIMS) lenses or switched from single vision (SV) to DIMS lenses for a 1-year period following a 2-year myopia control trial.
Methods: 128 children participated in this study. The children who had worn DIMS lenses continued to wear DIMS lenses (DIMS group), and children who had worn SV lenses switched to wear DIMS lenses (Control-to-DIMS group). Cycloplegic spherical equivalent refraction (SER) and axial length (AL) were measured at 6-month interval. Historical controls were age matched to the DIMS group at 24 months and used for comparing the third-year changes.
Results: Over 3 years, SER and AL changes in the DIMS group (n=65) were −0.52±0.69D and 0.31±0.26 mm; these changes were not statistically significant over time (repeated measures analysis of variance, p>0.05). SER (−0.04±0. 38D) and AL (0.08±0.12 mm) changes in the Control-to-DIMS group (n=55) in the third year were less compared with the first (mean difference=0.45 ± 0.30D, 0.21±0.11 mm, p<0.001) and second (0.34±0.30D, 0.12±0.10 mm, p<0.001) years. Changes in SER and AL in both groups over that period were significantly less than in the historical control group (DIMS vs historical control: mean difference=−0.18±0.42D, p=0.012; 0.08±0.15 mm, p=0.001; Control-to-DIMS versus historical control: adjusted mean differences=−0.30±0.42D, p<0.001; 0.12±0.16 mm, p<0.001).
Conclusions: Myopia control effect was sustained in the third year in children who had used the DIMS spectacles in the previous 2 years and was also shown in the children switching from SV to DIMS lenses.
Lam CS, Tang WC, Lee PH, et al. Myopia control effect of defocus incorporated multiple segments (DIMS) spectacle lens in Chinese children: results of a 3-year follow-up study. British Journal of Ophthalmology Published Online First: 17 March 2021.