Dual-Index Aspherical Lenslets deliver on myopia control in Singaporean kids

Wearing spectacle lenses with Dual-Index Aspherical Lenslets (DIAL) appears to be more efficacious at slowing myopia progression in children when compared with single-vision spectacle lenses (SVLs), as shown in a study from Singapore.

Over a 1-year follow-up, children who wore DIAL-embedded spectacle lenses showed significantly less change in axial length (0.04 vs 0.22 mm; mean difference, −0.18 mm, 95 percent confidence interval [CI], −0.26 to −0.10; p<0.001) and spherical equivalent refraction (−0.13 vs −0.39 D; mean difference, 0.26 D, 95 percent CI, 0.06–0.46; p=0.01) compared with those who wore SVLs. [Ophthalmol Sci 2025;5:100766]

Notably, DIAL showed a more pronounced effect on myopia control for younger children (8 to <11 years) than for older children (11–13 years). Specifically, axial elongation in the DIAL group was 0.29-mm less for younger children and 0.09-mm less for older children relative to those in the SVL group (p=0.004 for interaction).

No significant between-group differences were observed for distance best-corrected visual acuity (BCVA) (p=0.36) and near BCVA (p=0.88). Mean daily wearing time was 12.8 hr/day in the DIAL group and 13.3 hr/day in the SVL group (p=0.53), with all children adapting to their spectacle lenses within 3 to 4 days.

In terms of safety, 12 adverse events (AEs) occurred during the study, including mild discomfort upon wearing the spectacle lenses. Most of these events were mild and unrelated to the study device. None of the children had severe AEs.

“The absence of treatment-related AEs indicates safety and comfort of DIAL spectacle lenses for myopia control in children,” according to the investigators.

How DIAL works

DIAL was developed based on the principles of the highly aspherical lenslets (HAL), they said. It works by delivering two distinct optical signals: one to correct vision directly on the retina, and a second to actively manage myopia progression. But unlike HALs, DIALs are embedded within the lens.

The array of contiguous aspherical lenslets, formed at the interface of the front and back layers of the spectacle lenses, is arranged in a hexagonal mesh, the investigators explained. “This array creates an average envelope parallel to the front lens surface curvature.

“Our data showed that the cumulative absolute reduction in axial elongation of the DIAL spectacle lenses at 0.18 mm was not significantly different from that of the HAL spectacle lenses at 0.21 mm after 1 year, showing comparable myopia control efficacies between the DIAL and HAL spectacle lenses,” they noted. [Br J Ophthalmol 2022;106:1171-1176]

In the study, the investigators enrolled 80 myopic children (52.5 percent male, 87.5 percent Chinese) between 8 and 13 years of age (mean 10.8 years). Half of them were randomly assigned to wear DIAL-embedded spectacle lenses and the other half, to wear SVLs. A total of 76 children completed the 1-year follow-up, including 38 in each group.

Subjective refraction was used to determine the distance prescription of the spectacle lenses. The spectacles were replaced at each 6-month follow-up visit regardless of change in prescription.