Aspherical lenslets are designed with 11 concentric rings engineered unnoticeably into eyeglass lenses to create “defocused” light in front of the retina, matching its curve. These rays may signal a young eye not to grow longer, according to 1-year interim results of a clinical trial, published in the British Journal of Ophthalmology. In fact, 26% of children wearing spectacles with highly aspherical lenslets (HAL) and 5% of those using slightly aspherical lenslets (SAL) experienced decreased axial length (AL), compared with 0% in a control group wearing single vision lenses (SVL).
The multi-year study began in 2018 and continues at Eye Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, China. Of 170 children 8 years to 13 years old who began the trial, 161 completed study protocols. At baseline and 6-month intervals, cycloplegic autorefraction for spherical equivalent refraction (SER), AL, and best-corrected visual acuity were assessed. Participants displayed myopia from -0.75 D to -4.75 D, and astigmatism 1.50 D or lower, but had no ocular disease. The patients were randomized 1:1:1 to receive polycarbonate eyeglasses with HAL, SAL, or SVL.
At 12 months, HAL reduced AL elongation 0.23 mm more than controls, and SAL 0.11 mm more than SVL (both P <.001). After adjusting for factors such as baseline age, and age of myopia onset, the mean changes in AL translated to a 61% reduction in AL lengthening for HAL and 31% less elongation for SAL when compared with SVL wearers. Notably, younger children at baseline were more likely to experience significantly increased AL change in SAL and SVL cohorts (both P <.001), but not with HAL.
Participants displayed 0.53 D more stable SER in the HAL group and 0.33 D less SER progression with SAL, than with SVL (P <.001). Model-adjusted data showed slowing of myopia by 0.50 D for those wearing HAL and by 0.32 D for children in SAL lenses, compared with controls. Younger patients exhibited significantly faster progression of myopia in the SVL set, but not in the HAL cohort (P =.20), or SAL group (P =.11). Interestingly, 20% of those wearing HAL, 4% with SAL, and 0% of SVL wearers showed a hyperopic shift, the study adds.
Mean time spent wearing eyeglasses daily ranged from 12.9 to 13.6 hours and did not differ significantly between cohorts (P =.35). Also, the 3 groups adjusted comparably to their spectacles; in 3 days 90% of those wearing HAL adapted, 100% in SAL, and 94% in SVL. All patients fully adapted within 1 week, with no complaints reported in phone interviews and 6-month surveys. No adverse events were noted.
The sample included children of Chinese descent. No other ethnic populations participated, representing a limitation of this study relating to generalizability. In addition, phone and in-person surveys comprised subjective methods to tally hours that spectacles were worn.
Investigators explain that aspherical lenses bend light rays in a non-linear contour before the retina — the constant 3-dimensional signal is known as volume of myopic defocus (VoMD). “HAL induced a larger VoMD in front of the retina than SAL based on optical modeling; hence, we hypothesize that a larger VoMD will be more effective at controlling myopia progression.”
Disclosure: Several study authors declared affiliations with the biotech or pharmaceutical industries. Please see the original reference for a full list of authors’ disclosures.
Bao J, Yang A, Huang Y, et al. One-year myopia control efficacy of spectacle lenses with aspherical lenslets. Bri J Ophthalmol. Published online April 2, 2021. doi:10.1136/bjophthalmol-2020-318367