Myopia control with cylindrical annular refractive element (CARE) spectacle lenses: one year results

Paper title: One-year myopia control efficacy of cylindrical annular refractive element spectacle lenses

Authors: Xinting Liu (1), Pengqi Wang (1), Zhu Xie (1), Muhan Sun (1), Minfeng Chen (1), Jiefang Wang (1), Jing Huang (1), Siyun Chen (1), Zhaohe Chen (1), Yanli Wang (1), Yiyu Li (1), Jia Qu (1), Xinjie Mao (1)

1. School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China

Date: 31 January 2023

Reference: Liu X, Wang P, Xie Z, Sun M, Chen M, Wang J, Huang J, Chen S, Chen Z, Wang Y, Li Y, Qu J, Mao X. One-year myopia control efficacy of cylindrical annular refractive element spectacle lenses. Acta Ophthalmol. 2023 Sep;101(6):651-657.

A new innovation in myopia controlling spectacle lens technology employs micro-cylinders arranged in concentric circles with a central clear zone of full correction. 

• Each micro-cylinder has a radial interval of 1.2mm and brings +8.00D of cylinder power.  
• The micro-cylinders create high-order aberrations (HOAs) to achieve a blur signal on the retina. The central clear zone is 9.4mm in diameter. 
• The lens design is based on the higher order aberrations theory whereby it is proposed that certain optical imperfections in the eye (HOAs) may play a role in myopia development and progression.

This randomized control trial involved Chinese children (n=118) aged 8 to 12 years old with myopia of -1.00D to -4.00D and astigmatism of <-1.50DC and were randomly assigned cylindrical annular refractive element (CARE) spectacle lenses (n=61) or SV lenses (n=57). 1-year results indicate myopia progression was slower with CARE lenses (−0.56D) compared to SV lenses (−0.71D), with a 0.14D difference in progression (a 21% reduction), which was not significantly different. Axial length progression was also less with CARE (0.27mm) compared to single vision (0.35mm), showing a 0.09mm difference (95% confidence interval: 0.02 to 0.15mm myopia control effect), representing a significant 23% reduction in progression.

This one-year data shows a myopia control effect with the new CARE lenses, and that these lenses are safe, well tolerated and provide acceptable visual acuity. However, its efficacy is perhaps slightly less than other myopia control spectacle lens options on the market: 1-year axial length differences between treatment and control groups were 0.21mm for DIMS,¹ 0.23mm for the HAL lens² and 0.15mm for the DOT lens,³ each representing a minimum 50% myopia slowing effect compared to the single vision control group.³  It is important to note that only a direct comparison in a study would support indication of differential efficacy. 

While these are only 1-year results, it is unlikely that long-term data will provide different insights given myopia control strategies tend to demonstrate their highest effectiveness during the early phase of treatment.⁴

The study notably reports a better myopia control effect in the latter half of the treatment year with CARE lenses, which is at odds with previous studies.^1-2,6 The authors surmise this may be due to increased compliance to full-time wear by the participants. Hence, it is worthwhile awaiting 2-year results of the trial.

Ultimately, some myopia control treatment is better than no myopia control treatment and CARE lenses therefore remain an important tool in the myopia control toolkit, especially if there is a scarcity of available options.

• The applicability of the findings related to the myopia control benefits of CARE lenses may primarily pertain to Chinese children, necessitating further studies in diverse ethnic populations. However, this should not be a barrier when prescribing as research shows that the benefit of myopia control treatment appears similar regardless of ethnicity.⁷
• The study authors plan to refine the patented lens design further for the upcoming final year of the study, hence new outcomes will be reported.
• Due to the noted non-compliance with full-time wear in some of the study’s participants, it is important to see how the outcomes are affected in the 2^nd phase of the trial with improved adherence to full-time wear.

Title: One-year myopia control efficacy of cylindrical annular refractive element spectacle lenses

Authors: Xinting Liu, Pengqi Wan, Zhu Xie, Muhan Sun, Minfeng Chen, Jiefang Wang, Jing Huang, Siyun Chen, Zhaohe Chen, Yanli Wang, Yiyu Li, Jia Qu, Xinjie Mao

Purpose: To evaluate the 1-year myopia control efficacy of a spectacle lens with annular cylindrical microstructures.

Methods: A total of 118 consecutive eligible children aged 8–12years with −1.00 D to −4.00 D of spherical component myopia and<1.50 D astigmatism were enrolled between August 2020 and November 2020 at the Eye Hospital of Wenzhou Medical University. Participants were randomly assigned to wear cylindrical an-nular refractive element (CARE) (n=61) or single-vision (n=57) spectacle lenses. Cycloplegic autorefraction (spherical equivalent refraction [SER]) and axial length (AL) were measured at baseline and 6-month intervals. Adaptation and compliance questionnaires were administered during all visits.

Results: Among 118 randomized participants, 96 (81.4%) were included in the analyses (mean [SE] age, 10.4 [0.6] years; 49 [51.0%] were female; mean [SE] spherical equivalent refractive error, −2.67 [0.66]D; mean [SE] axial length, 24.75 [0.77]mm). Adjusted 1-year myopia progression was −0.56 D for CARE and −0.71 D for single-vision spectacle lenses. The difference in progression was 0.14 D (95% CI,−0.04 to 0.32) for CARE vs single vision. Adjusted 1-year eye growth was 0.27mm for CARE and 0.35mm for single vision. The difference in eye growth was 0.09mm(95% CI, −0.15 to −0.02) for CARE vs single vision. All groups adapted to their lenses with no reported adverse events, complaints, or discomfort.

Conclusions: Among children with myopia, treatment with cylindrical annular refractive element spectacle lenses significantly reduced the rate of axial elongation over 1 year compared with single-vision spectacle lenses.