Pediatric patients who wore Defocus Incorporated Multiple Segments spectacle lenses appeared to maintain slower axial elongation through late adolescence during a follow-up of nearly 10 years. The findings suggested a sustained biological effect on eye growth, although the long-term effect on refractive error was less consistent.
Researchers conducted an observational posttrial follow-up of participants from the original clinical trial in which patients were randomly assigned to receive Defocus Incorporated Multiple Segments (DIMS) spectacle lenses or single-vision spectacle lenses. The analysis included 60 patients who completed a final examination at a mean follow-up of 9.4 years from the original baseline, when participants had been aged 8 to 13 years. Longitudinal changes in axial length and spherical equivalent refraction (SER) were analyzed using linear mixed-effects models that compared periods of DIMS wear with modeled periods of single-vision spectacle wear.
The primary outcomes were cumulative changes in cycloplegic SER and axial length. The researchers evaluated whether the treatment effects varied with age and compared modeled axial elongation with published normative data from untreated Asian children.
The researchers showed that DIMS wear was associated with sustained slowing of axial elongation. The model predicted cumulative axial elongation of 0.44 mm among hypothetical continuous DIMS wearers compared with 1.27 mm among hypothetical continuous single-vision wearers, representing an estimated 65% reduction in axial elongation over the study period. The treatment effect was greatest at younger ages, particularly prior to 18 years.
When compared with published normative data from untreated Asian children, the modeled cumulative axial elongation among continuous DIMS wearers was approximately 76% lower. The researchers emphasized that this comparison provided contextual benchmarking rather than a direct control group comparison.
The findings for refractive error were less definitive. Although the model predicted less cumulative myopia progression with continuous DIMS wear (−0.57 diopters vs. −2.17 diopters with modeled single-vision wear), the primary longitudinal analysis did not identify a statistically significant treatment effect on SER. The researchers suggested that variability in long-term autorefraction measurements and the absence of a contemporaneous untreated control group may have limited the model's ability to detect differences in refractive outcomes.
The researchers acknowledged several limitations. Because the study was an observational follow-up, it lacked a contemporaneous untreated or continuous single-vision control group, as all participants had previous exposure to DIMS lenses. Attrition over nearly a decade reduced the study population from the original trial and may have introduced survivor bias. In addition, variable follow-up intervals required statistical modeling rather than direct comparisons across study visits.
Overall, the findings suggested that DIMS spectacle lenses may provide durable long-term control of axial elongation through late adolescence. The researchers noted that additional studies with appropriate long-term control groups are needed to better understand the apparent difference between sustained control of axial length and the less consistent findings for refractive error.
"[T]his long-term follow-up study provides robust evidence that the effects of DIMS wear on slowing axial elongation are sustained through late adolescence," wrote lead study author Tsz Wing Leung, of the Centre for Myopia Research at the School of Optometry at The Hong Kong Polytechnic University, and colleagues.
The study was funded by HOYA Holdings. Co–study author Natalia Vlasak is an employee of HOYA Vision Care and senior study author Carly Siu-yin Lam is a patent holder for DIMS Technology. The study authors reported no other conflicts of interest.
Source: BMJ Open Ophthalmology