Myopia control efficacy over three years with highly aspherical lenslet (HAL) spectacle lenses

Paper title: Myopia Control Efficacy of Spectacle Lenses with Aspherical Lenslets: Results of a 3-year Follow-up Study

Authors: Xue Li (1,2,3), Yingying Huang (1,2,3), Ziang Yin (1,2), Chenyao Liu (1,2), Siqi Zhang (1,2), Adeline Yang (3,4), Björn Drobe (3,4), Hao Chen (1,2), Jinhua Bao (1,2,3)

1. Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
2. National Engineering Research Center of Ophthalmology & Optometry, Wenzhou, Zhejiang, China
3. Wenzhou Medical University-Essilor International Research Center (WEIRC), Wenzhou Medical University, Wenzhou, Zhejiang, China

Date: Apr 2023

Reference: Li X, Huang Y, Yin Z, Liu C, Zhang S, Yang A, Drobe B, Chen H, Bao J. Myopia Control Efficacy of Spectacle Lenses with Aspherical Lenslets: Results of a 3-year Follow-up Study. Am J Ophthalmol. 2023 Apr 9: S0002-9394(23)00147-2.

[Link to open access paper]

This study is an extension of a previous randomised clinical trial in China by the same authors.¹ Lenses with highly aspherical (HAL) and slightly aspherical (SAL) lenslet designs were found to slow myopia progression compared to single vision lenses over 2-years of wear. Read our Myopia Profile Science Summary on this paper here.

The study aim was to determine if HAL lenses could sustain myopia control for a further year of wear and to assess long-term efficacy of continued treatment. Further aims were to assess myopia control efficacy of HAL lenses for myopic children switching from wearing SAL or single vision lens designs for 2yrs.

• Previous HAL wearers continuing to wear HAL were labelled as HAL1 group (n = 51). The original SAL and single vision lens wearers switching to HAL were now in HAL2 (n = 50) and HAL3 (n = 42) groups, respectively.
• A new control group (nSVL, n = 48) was recruited to the study and matched for sex, age, spherical equivalent refractive error (SER) and axial length (AL). Their data was combined with the original control group to assess myopia control efficacy over 3yrs. SER and AL were measured 6-monthly in the 3^rd year.
• A total of 191 children across all the groups completed the extension study, with an age range of between 8 and 13yrs (mean age 10.4yrs).

Myopia progression and axial elongation were similar across all 3 HAL groups in the 3^rd year. After one year of wearing HAL lenses, the mean SER progression was -0.38D, -0.36D and -0.33D in the HAL1, HAL2 and HAL3 groups, respectively compared to -0.56D mean progression in the nSVL group.

Mean changes in AL over the year were 0.17mm, 0.18mm and 0.14mm for HAL1, HAL2 and HAL3, respectively compared to the mean change in AL for nSVL group being 0.28mm.

The proportion of those with 0.50D or more progression and those who didn't progress at all, was 25% and 20% in HAL1, 26% and 18% in HAL2, 26% and 24% in HAL3 and 46% and 6% in nSVL.

Over the 3yrs, mean myopic progression and AL growth was shown to be -0.99D and 0.49mm in the HAL/HAL1 group and -2.05D and 0.98mm in the combined control groups.

• Compared to single vision lenses, HAL design spectacle lenses were able to maintain myopia control effect over 3yrs for those who had previously worn them.
• Children swapping from single vision or SAL design lenses experienced a significant slowing of their myopia progression and axial elongation compared to the control group. This is good news for older children starting myopia management after wearing single vision lenses.
• There were no adverse responses to wearing HAL lenses.

Similar results were found across all the HAL groups for the 3^rd year.

• This reflects results from other studies where participants had switched myopia management treatment mid-trial. Chamberlain et al² found that children swapping from a single vision contact lens to a dual focus design experienced a similar treatment effect to those who had worn them continuously in the same period. Lam et al³ recorded similar when children swapped to wearing DIMS spectacle lenses after wearing single vision.
• The results from this study suggest myopia control efficacy of HAL lenses may not be influenced by prior treatment options (or no treatment). Further study will confirm if this holds true for prior treatments such as contact lenses or atropine.

This study did not aim to examine rebound effects, although a recent cross-over trial⁴ showed no myopia rebound for children wearing HAL. The authors report the HAL/HAL1 group will be followed for a further 2yrs in order to assess long-term efficacy over a 5yr period. Further research could confirm long-term efficacy is retained once wear is ceased.

Title: Myopia Control Efficacy of Spectacle Lenses with Aspherical Lenslets: Results of a 3-year Follow-up Study

Authors: Xue Li, Yingying Huang, Ziang Yin, Chenyao, Siqi Zhang, Adeline Yang, Björn Drobe, Hao Chen, Jinhua Bao

Purpose: To investigate myopia control efficacy in children who continued wearing spectacle lenses with highly aspherical lenslets (HAL) or switched from spectacle lenses with slightly aspherical lenslets (SAL) and single-vision spectacle lenses (SVL) to HAL for one year following a 2-year myopia control trial.

Methods: This was a one-year extension from a randomized clinical trial. Of the 54 children who had worn HAL for two years, 52 continued wearing HAL (HAL1 group), and of the 53 and 51 children who had originally worn SAL or SVL, 51 and 48 switched to wearing HAL (HAL2 and HAL3 groups) in the 3rd year, respectively. A new SVL (nSVL) group of 56 children was recruited, matched for age, sex, cycloplegic spherical equivalent refraction (SER), and axial length (AL) of the HAL3 group at extension baseline, and used for a comparison of third-year changes. SER and AL were measured every 6 months in the 3rd year.

Results: During the 3rd year, the mean (SE) myopia progression in the nSVL group was -0.56 (0.05) D. Compared with nSVL, the changes in SER were less in HAL1 (-0.38[0.05] D, P=0.02), HAL2 (-0.36[0.06] D, P=0.01) and HAL3 (-0.33[0.06] D, P=0.005). The mean (SE) AL elongation in the nSVL group was 0.28(0.02) mm. Compared with nSVL, the elongation in AL was less in HAL1 (0.17[0.02] mm, P<0.001), HAL2 (0.18[0.02] mm, P<0.001) and HAL3 (0.14[0.02] mm, P<0.001). Myopia progression and axial elongation were comparable in all 3 HAL groups (all P>0.05) in the third year.

Conclusions: Myopia control efficacy has remained in children who wore HAL in the previous 2 years. Children who switched from SAL or SVL to HAL in the 3rd year had slower myopia progression and axial elongation than that in control group.

[Link to open access paper]