Long-term wear of Defocus Incorporated Multiple Segments spectacle lenses was associated with slower axial elongation through late adolescence in an observational follow-up of a prior randomized clinical trial cohort, researchers reported.
However, the researchers noted that the follow-up did not include a contemporaneous untreated control group, and the primary longitudinal model did not show a statistically significant treatment effect on spherical equivalent refraction progression.
In the study, researchers evaluated 60 young adults from the original Defocus Incorporated Multiple Segments (DIMS) spectacle lens trial. The original randomized trial enrolled children aged 8 to 13 years with myopia from −1.00 to −5.00 D, astigmatism and anisometropia of 1.50 D or less, and no history of ocular disease or prior myopia-control interventions. In the original trial, participants were randomized to DIMS or single-vision spectacle lenses for 2 years, but the single-vision group switched to DIMS lenses at the beginning of year 3.
The final analysis included participants followed for a mean of 9.4 years, from a mean baseline age of 10.5 years to a mean final age of about 20 years. Of 90 participants who completed the 6-year follow-up, 63 returned for the final visit, representing 39% retention from the original randomized trial baseline cohort of 160 participants. Three were excluded because of other myopia-control intervention use or incomplete lens-wear data, leaving 60 participants in the analysis.
Researchers used linear mixed-effects models to assess annualized changes in axial length and spherical equivalent refraction between visits. The models included age, lens-wear status, and their interaction. Researchers then used bootstrapping to estimate cumulative outcomes under hypothetical continuous DIMS wear vs hypothetical continuous single-vision spectacle lens wear.
For axial length, the model showed slower axial elongation during periods of DIMS wear compared with periods of single-vision wear. The model predicted cumulative axial elongation of 0.44 mm with continuous DIMS wear vs 1.27 mm with continuous single-vision wear, corresponding to a 65% modeled reduction over the follow-up period.
The axial-length effect appeared greater at younger ages, with the treatment effect more pronounced before age 18 years. Researchers also compared the modeled DIMS trajectory with an external untreated Asian normative model from Brennan et al, which predicted 1.85 mm of cumulative axial elongation over the same period. Compared with that external benchmark, continuous DIMS wear was associated with an estimated 76% lower cumulative axial elongation.
The refractive findings were less straightforward. The linear mixed-effects model did not find a statistically significant main effect of DIMS wear or a statistically significant interaction with age for spherical equivalent refraction progression. Still, the researchers described an apparent paradox: cumulative model predictions estimated less myopia progression with continuous DIMS wear than with continuous single-vision wear, and the researchers characterized that cumulative difference as statistically significant based on nonoverlapping confidence intervals.
The researchers suggested this discrepancy may reflect a low signal-to-noise ratio in long-term autorefraction measurements. They reported that the spherical equivalent refraction model had an intraclass correlation coefficient of 0.003, indicating that 99.7% of the variance was unexplained residual noise. They also noted that single-vision wear periods in the long-term model may not represent untreated progression because all analyzed participants had prior DIMS exposure.
The study had several limitations. It was observational and did not provide a new randomized comparison of DIMS vs single-vision lenses over nearly 10 years. Treatment estimates depended on statistical modeling, and attrition may have introduced survivor bias because participants who remained in the study may have had favorable myopia control, high tolerance, or greater satisfaction with DIMS lenses. The reduced sample size also limited statistical power for subgroup analyses, including the RPR cohort. Variable follow-up durations required modeling rather than direct visit-to-visit comparisons.
“These findings support the continuous clinical prescription of DIMS lenses through late adolescence for durable myopia control, while cautioning practitioners that long-term treatment success must be evaluated using cumulative metrics rather than inherently noisy visit-to-visit autorefraction changes,” wrote lead study author Tsz Wing Leung, of The Hong Kong Polytechnic University, and colleagues.
Disclosures: The study was supported by HOYA Holdings NV and the InnoHK initiative of the Innovation and Technology Commission of the Hong Kong Special Administrative Region Government. The researchers thanked the sponsor for assistance reviewing the final manuscript. Natalia Vlasak is a staff member of HOYA Vision Care. Carly Siu-yin Lam is a patent owner of DIMS Technology. The researchers reported that Gemini 2.50 Pro was used to polish the writing and debug the Python code used for statistical analysis.
Source: BMJ Open Ophthalmology