Trial: 1-Year Results Show Aspherical Lenslets Decrease Axial Elongation

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.

Reference

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