Spectacles with highly aspherical lenslets for pre-myopia

Paper title: Spectacle lenses with highly aspherical lenslets for slowing axial elongation and refractive change in low-hyperopic Chinese children: a randomized controlled trial

Authors: Zhang, Zhe (1, 3, 4), Zeng, Li (1, 3, 4), Gu, Dantong (2), Wang, Bingjie (5), Kang, Pauline (5), Watt, Kathleen (5), Zhou, Jiaqi (1, 3, 4), Zhou, Xueyi (1, 3, 4), Chen, Zhuoyi (1, 3, 4), Yang, Danjuan (1, 3, 4), Chen, Can (1, 3, 4), Wang, Xiaoying (1, 3, 4), Zhou, Xingtao (1, 3, 4), Chen, Zhi (1, 3, 4)

1. Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, China
2. Clinical Research and Achievement Translation Center, Eye & ENT Hospital, Fudan University, Shanghai, China
3. NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
4. Shanghai Research Center of Ophthalmology and Optometry, Shanghai, China
5. School of Optometry and Vision Science, University of New South Wales, Sydney, Australia

Date: Aug 2024

Reference: Zhang Z, Zeng L, Gu D, Wang B, Kang P, Watt K, Zhou J, Zhou X, Chen Z, Yang D, Chen C, Wang X, Zhou X, Chen Z. Spectacle Lenses With Highly Aspherical Lenslets for Slowing Axial Elongation and Refractive Change in Low-Hyperopic Chinese Children: A Randomized Controlled Trial. Am J Ophthalmol. 2024 Aug 27;269:60-68.

[Link to open access paper]

There are a number of myopia control interventions which have demonstrated efficacy for reducing myopia progression in children. However, there is limited research into methods to delay the onset of myopia in children at high risk of becoming myopic. It is known that the biggest risk factor for developing myopia is being less hyperopic than age-normal,¹ which in the current paper is termed ‘hyperopic reserve’. The impact of preventing myopia in children with low hyperopic reserve is significant, with the reduction in the final level of myopia being potentially greater when delaying myopia onset by one year, compared to the effect of 2-3 years of myopia control treatment in already myopic children.² As for preventive measures for pre-myopic children, the options are limited - with only outdoor time and low-dose atropine (0.01%, 0.025% and 0.05%) previously explored in controlled clinical trials.^3-7

This study investigated the efficacy of spectacle lenses with highly aspherical lenslets (HAL) as an intervention for slowing axial elongation and myopia development in children with low hyperopic reserve. 108 Chinese children aged 6 to less than 10 years, with spherical equivalent refractive error 0.00 to +2.00 D, were randomly assigned either HAL or single vision lens (SVL) spectacles to wear at least 5 days per week and at least 4 hours per day. All lenses were prescribed with 0.00 dioptres. Cycloplegic refraction, axial length (AL), and uncorrected visual acuity were measured at baseline, 6 and 12 months after dispensing. The results were as follows.

HAL spectacles utilise a novel optical design that has been established to be effective in controlling axial elongation and myopic progression in already myopic children.⁸ This data shows that children with low ‘hyperopic reserve’, or pre-myopia, who are therefore at higher risk of developing myopia, can also potentially benefit from this treatment, provided longer wearing hours (at least 30 hours/week) are achieved. HAL spectacles could potentially be a safer alternative to atropine due to the lack of side effects, although the long-term effect in attempting to delay myopia onset is not yet known.

This study is the first to explore the use of optical interventions to delay myopia onset, therefore providing valuable insight into the viability of myopia control in pre-myopic children. This raises questions as to whether other myopic control spectacle or even contact lens designs, can achieve a similar treatment efficacy.

This study was undertaken in Chinese children, aged 6 to less than 10 years, with cycloplegic refractions from plano to +2.00D. A previous study in this population has shown that a ‘hyperopic reserve’ of at least +1.50D was required to offset myopia onset risk within a mean 1.3 years of follow up, regardless of age.⁹ Another recent Chinese study cited the ‘mean hyperopic reserve’ as 2.08D at 6 years, 1.49D at 8 years and 1.04D at 10 years.¹⁰

By contrast, the well-known CLEERE study in North America (36% White, 22% Hispanic) cited +0.75D as the cut-off for myopia risk in children aged 6 years, with lower ‘hyperopic reserve’ for older children.¹ This raises the question of what level of ‘hyperopic reserve’ is required to reduce myopia onset risk, based on age and ethnicity – fine-tuning the definition of pre-myopia.

While this is promising for the utility of HAL spectacles, longer studies are required to determine whether the treatment shows sustained efficacy and even whether the development of myopia can be prevented. Similar investigations should be conducted in other regions of the world, and studies consisting of multiple centers and larger study populations are warranted to improve the generalizability of results to other populations.

Title: Spectacle lenses with highly aspherical lenslets for slowing axial elongation and refractive change in low-hyperopic Chinese children: a randomized controlled trial

Authors: Zhang, Zhe, Zeng, Li, Gu, Dantong, Wang, Bingjie, Kang, Pauline, Watt, Kathleen, Zhou, Jiaqi, Zhou, Xueyi, Chen, Zhuoyi, Yang, Danjuan, Chen, Can, Wang, Xiaoying, Zhou, Xingtao, Chen, Zhi

Purpose: Spectacle lenses with highly aspherical lenslets (HAL) have been shown to effectively retard myopia progression in myopic children. This study aimed to investigate the impact of spectacle lenses with HAL on refractive and axial length (AL) changes in Chinese children with low amount of hyperopia.

Methods: A total of 108 Chinese children aged 6.0 to 9.9 years and spherical equivalent refractive error (SERE) from 0.00 to +2.00 D were randomly allocated into two groups: the HAL group and the single vision spectacle lens (SVL) group. Cycloplegic refraction, AL, and uncorrected visual acuity were measured at baseline, 6 and 12 months after lens dispensing. The duration of spectacle lens wear was monitored using a wearable device attached to the spectacle frame and by questionnaire logs provided by participants at each follow-up visit.

Results: The 1-year SERE change was -0.19 (-0.32, 0.03) D and -0.23 (-0.36, 0.05) D in the SVL and HAL groups (P = .883). The 1-year AL elongation was 0.24 (0.18, 0.34) mm and 0.19 (0.12, 0.27) mm in the SVL and HAL groups (P = .057). In the HAL group, changes in AL and SERE were significantly correlated to lens wearing time (P < .001 and P = .024, respectively). Participants in the HAL group who wore their lenses for more than 30 hours per week had significantly slower AL elongation (0.11 [0.05, 0.17] mm) compared to their SVL counterparts (0.27 [0.21, 0.33] mm) (P < .001).

Conclusions: Spectacle lenses with HAL significantly reduced AL elongation in low hyperopic children who wore lenses for over 30 hours per week. A dose-response relationship was evident with longer lens wearing time associated with less AL change.

[Link to open access paper]