Comparative evaluation of different (peripheral defocus based) spectacle designs in preventing myopia progression: A double-blinded randomised clinical trial.

Purpose: This study aimed to evaluate and compare the efficacy of different peripheral defocus-based spectacle designs [Defocus Induced Multiple Segment (DIMS), Highly Aspherical Lenslets (HALT) and Cylindrical Annular Refractive Elements (CARE)] in controlling myopia progression.

Methods: This was a prospective, interventional, double-blinded, randomised clinical trial. Children aged 5 to 15 years, with myopia ranging from -1 D to -8 D and documented myopia progression of ≥0.5 D/year, were randomly assigned (1:1:1) to wear either DIMS, HALT or CARE spectacles full-time. Cycloplegic refraction and axial length measurements were taken at baseline and after 1 year. The primary outcome was the change in the rate of myopia progression. All analyses were performed based on the intention-to-treat principle.

Results: A total of 120 participants (40 in each group: DIMS, HALT and CARE) with a mean age of 10.1 ± 3.3 years (57% male) were enrolled. At the 1-year follow-up, the rate of myopia progression reduced by 0.38 ± 0.13 D/year (56.7%), 0.36 ± 0.12 D/year (58.1%) and 0.31 ± 0.15 D/year (47%) for the DIMS, HALT and CARE groups, respectively. The respective change in axial length was 0.2 ± 0.11 mm, 0.19 ± 0.12 mm and 0.23 ± 0.14 mm. Inter-group comparisons showed a significant difference in spherical equivalent refractive error changes between HALT and CARE (p = 0.04) and in the rate of myopia progression between DIMS and CARE (p = 0.04). No significant differences were found between HALT and DIMS for any parameter.

Conclusions: Spectacle lenses incorporating peripheral defocus (DIMS, HALT and CARE) were all effective in reducing the rate of myopia progression significantly, with no adverse effects being observed. Among the three designs, DIMS and HALT exhibited comparable and significantly better efficacy than CARE spectacles at 1 year follow-up. However, further long-term studies are required to validate these findings.