The efficacy of positive and negative power lenslets in slowing myopia progression

Paper title: Novel Lenslet-Array-Integrated Spectacle Lenses for Myopia Control: A 1-Year Randomized, Double-Masked, Controlled Trial 

Authors: Su, Binbin (1), Cho, Pauline (2), Vincent, Stephen J (3), Zheng, Jingwei (1), Chen, Jiaojie (1), Ye, Cong (1), Wang, Tengfei (1), Zhang, Jingwei (1), Zhang, Kou (1), Lu, Fan (4), Jiang, Jun (5)

1. School of Optometry, Wenzhou Medical University, Wenzhou, China
2. School of Optometry, The Hong Kong Polytechnic University, Hong Kong, China
3. School of Optometry and Vision Science, Queensland University of Technology, Brisbane, Australia
4. Department of Ophthalmology, Peking University Third Hospital, Beijing, China
5. Eye Hospital, Wenzhou Medical University, Wenzhou, China 

Date: Published online July 6, 2024 

Reference: Su B, Cho P, Vincent SJ, Zheng J, Chen J, Ye C, Wang T, Zhang J, Zhang K, Lu F, Jiang J. Novel lenslet-array-integrated spectacle lenses for myopia control: a 1-year randomized, double-masked, controlled trial. Ophthalmology. 2024 Dec;131(12):1389-1397. doi: 10.1016/j.ophtha.2024.07.002.

[Link to abstract]

Current myopia control optical interventions such as orthokeratology, multifocal contact lenses, and spectacle lenses with positive power lenslets are believed to work by providing peripheral myopic defocus to the retina

To understand how other mechanisms, such as wavefront modulation and retinal contrast alteration may influence myopia progression, two designs of Lenslet-Array-Integrated (LARI) spectacle lenses were developed to alter higher-order wavefront aberrations. Both contain a clear central optic zone and incorporate a hexagonal array pattern with lenslets of +3D additional power (PLARI) or -3D additional power (NLARI). 

The purpose of this study was to compare myopia control efficacy of the positive and negative power lenslets and assess whether negative lenslets could also reduce myopia progression in children.

This was a randomized, double-masked, controlled clinical trial with 231 children aged 6 to 12 years with myopia between -1 and -4D. They were assigned to wear PLARI, NLARI, or single-vision (SV) control lenses after eye examinations which included cycloplegic auto-refraction and AL measurement. Outcomes included changes in spherical equivalent refraction (SER) and axial length (AL) measured at baseline, 6 months, and 12 months.

After 12 months, both PLARI and NLARI lenses demonstrated significantly less SER progression and axial elongation compared to SV lenses, with no significant differences found between PLARI and NLARI groups for SER and AE at 6 or 12 months.

• PLARI and NLARI slowed SER and AE progression by 55% and 68% and 44% and 50% respectively.
• One-third of participants in PLARI and NLARI groups showed no myopia progression over 1 year, compared to 7.7% in the SV group.

Age was significantly correlated with faster SER progression and axial elongation in the SV and PLARI groups but not in the NLARI group.

Adaptation rates were high across all groups, with most participants fully adapting within 2 weeks. No significant adverse events were reported across the three groups.

This study was able to demonstrate that both lens types were able to reduce myopia progression in children and were well tolerated. 

• Although there was no significant difference in lens performance over the study duration, faster progression was seen in younger children wearing the PLARI lens, but not NLARI.
• This suggests that the NLARI design could provide efficacy across a range of age groups and may have a stronger effect on younger children who typically progress faster. 

Both lens types demonstrate potential for being myopia control spectacle lenses eyecare practitioners ECPs can consider when formulating personalised treatment plans for their myopic patients. However, understanding how progression rates change with age for young children is an important consideration when choosing any myopia control intervention, where greater efficacy may be achieved for young children with timely intervention. 

The NLARI lens features a novel design which alters higher-order, irregular wavefront aberrations. 

• The non-coaxial array design appears to give low-level blur at all distances, in contrast to the PLARI lenses which alters focal planes by presenting lower-order defocus effects.
• The ‘spatial phase modulation’ with the NLARI design is an exciting new development that may play a key role in myopia control if higher-order aberrations at all distances can reduce progression and could provide us with a different mechanism of myopia control.

While this study confirms that both PLARI and NLARI lenses are effective for slowing myopia progression, several important questions remain:

• What the potential rebound effects may be on ceasing wear.
• How the lens efficacy might differ for children younger than 6yrs and older than 12yrs and for myopia stronger than -4D
• What the precise underlying mechanism is for the NLARI lens and what insights into the development and management of myopia it can offer
• Further research will clarify how the NLRAI lens could be utilised in individualised treatment plans

Limitations to this study include

The study was limited to Chinese children, which may mean the results cannot be generalised to children from other ethnic backgrounds with different patterns of myopia progression. Future research should explore the efficacy of these lenses in more diverse populations.

The trial duration was only one year. Longer-term studies are needed to confirm whether the myopia control effects of PLARI and NLARI lenses are sustained throughout childhood. These would also confirm long-term acceptance of wear.

Title: Novel Lenslet-ARray-Integrated Spectacle Lenses for Myopia Control

Purpose: To investigate the myopia control efficacy of novel Lenslet-ARray-Integrated (LARI) spectacle lenses with positive power lenslets (PLARI) and negative power lenslets (NLARI) worn for 1 year in myopic children.

Design: Randomized, double-masked, controlled clinical trial.

Participants: A total of 240 children 6 to 12 years of age with spherical equivalent refraction (SER) between -4.00 and -1.00 diopters (D), astigmatism of ≤ 1.50 D, and anisometropia of ≤ 1.00 D.

Methods: Participants were assigned randomly in a 1:1:1 ratio to PLARI, NLARI, and control (single-vision [SV]) groups. Cycloplegic autorefraction and axial length were measured at baseline and 6-month intervals after lens wear.

Main Outcomes measures: Changes in SER, axial elongation (AE), and differences between groups.

Results: After 1 year, SER changes and AE in the PLARI and NLARI groups were significantly less than those in the SV group (SER: -0.30 ± 0.48 D, -0.21 ± 0.35 D, and -0.66 ± 0.40 D, respectively; AE: 0.19 ± 0.20 mm, 0.17 ± 0.14 mm, 0.34 ± 0.18 mm, respectively; all P < 0.001). No significant differences were found in SER changes and AE between PLARI and NLARI groups (P = 0.54 and P = 1.00, respectively). Younger age was associated with more rapid SER increase and larger AE in the SV group (r = 0.40 [P < 0.001] and r = -0.59 [P < 0.001], respectively) and PLARI group (r = 0.46 [P < 0.001] and r = -0.52 [P < 0.001], respectively), but not in the NLARI group (r = -0.002 [P = 0.98] and r = -0.08 [P = 0.48], respectively).

Conclusions: Compared with the SV group, both PLARI and NARI groups showed significantly slower myopia progression in terms of SER and AE. Faster myopia progression, in terms of both SER and AE, was associated with younger age in the SV and PLARI groups but not the NLARI group.

[Link to abstract]