While orthokeratology and soft multifocal lenses are excellent choices for managing myopia, contact lens options are not the only optical interventions that have shown promise for slowing myopia progression. While no U.S. Food and Drug Administration (FDA)-approved spectacle lenses are currently available for myopia control in the United States, it is important to understand the existing knowledge base and become familiar with developing technologies that may be available in the future.

BIFOCALS AND PROGRESSIVE ADDITION LENSES

Several studies have evaluated the use of bifocal or progressive addition lenses (PALs) for slowing childhood myopia progression. A randomized controlled trial of 135 Chinese-Canadian children found that those who wore +1.50D add executive bifocals experienced significantly less myopia progression and axial elongation over three years (Cheng et al, 2014). Children who have lower lag of accommodation experienced even greater treatment effects when the segment incorporated 3 Δ base-in per eye (Cheng et al, 2014).

Children wearing PALs have also been found to experience less myopia progression over 12 months (Varnas et al, 2021). While the reported myopia control treatment effects of bifocals and PALs are often less than those reported with orthokeratology and soft multifocal lenses, these spectacle designs do represent one option in an eyecare practitioner’s toolkit.

PERIPHERAL DEFOCUS LENSES

Multiple spectacle lenses specifically designed to slow myopia progression are in development and some are already available outside the U.S. Defocus Incorporated Multiple Segments (DIMS) and Highly Aspherical Lenslet Target (HALT) technologies incorporate relative peripheral plus power while maintaining unimpeded central vision (Lam et al, 2020; Bao et al, 2022).

DIMS technology employs around 400 individual peripheral lenslets of +3.50D, whereas HALT technology uses concentric rings of lenslets with varying powers (Lam et al, 2020; Bao et al, 2022). In contrast, Diffusion Optics Technology (DOT) lenses employ reduced peripheral contrast rather than relative plus power (Rappon et al, 2022). DOT lenses also incorporate a clear, unimpeded zone of central vision.

Although none of these technologies are available in the U.S., they have been shown to significantly slow myopia progression and axial elongation relative to untreated controls (Lam et al, 2020; Bao et al, 2022; Rappon et al, 2022).

ACTIVE STIMULATION LENSES

Outdoor illumination is both brighter and broader spectrum compared to indoor lighting, and spending more time outdoors is known to exert a protective effect against myopia (Dharani et al, 2021; Xiong et al, 2017). While the peripheral defocus designs described above all modify the retinal image shell of wearers, the brightness and spectral composition of retinal illumination remains unchanged.

In addition to peripheral defocus, active stimulation spectacle devices incorporate modified retinal illumination while maintaining clear central vision (Kubota, 2022). One active illuminated device that projects +4.00D defocused light at 1,600 cd/m2 and 5,700K was recently reported to significantly slow myopia progression and axial elongation in children over six months after only 1.5 hours of wear, five days per week (Kubota, 2022). It is possible that retinal defocus and modified retinal illumination act via different pathways.

THE FUTURE

There are many exciting technologies that may be available to our patients in the near future for myopia management. By staying abreast of these technologies, practitioners will be well-positioned to incorporate them into clinical practice when the next myopia control option becomes available. CLS

REFERENCES:

1. Cheng D, Woo GC, Drobe B, Schmid KL. Effect of Bifocal and Prismatic Bifocal Spectacles on Myopia Progression in Children: Three-Year Results of a Randomized Clinical Trial. JAMA Ophthalmol. 2014 Mar;132:258–264.
2. Varnas S, Gu X, Metcalfe A. Bayesian Meta-Analysis of Myopia Control with Multifocal Lenses. J Clin Med. 2021 Feb;10:730.
3. Lam CSY, Tang WC, Tse DY, et al. Defocus Incorporated Multiple Segments (DIMS) spectacle lenses slow myopia progression: a 2-year randomised clinical trial. Br J Ophthalmol. 2020 Mar;104:363-368.
4. Bao J, Yang A, Huang Y, et al. One-year myopia control efficacy of spectacle lenses with aspherical lenslets. Br J Ophthalmol. 2022 Aug;106:1171-1176.
5. Rappon J, Chung C, Young G, et al. Control of myopia using diffusion optics spectacle lenses: 12-month results of a randomised controlled, efficacy and safety study (CYPRESS). Br J Ophthalmol. 2022 Sep 1:bjophthalmol-2021-321005. [Online ahead of print]
6. Dharani R, Lee CF, Theng Z. et al. Comparison of measurements of time outdoors and light levels as risk factors for myopia in young Singapore children. Eye (Lond). 2012 Jul;26:911-918.
7. Xiong S, Sankaridurg P, Naduvilath T, et al. Time spent in outdoor activities in relation to myopia prevention and control: A meta-analysis and systematic review. Acta Ophthalmol. 2017 Sep;95:551-566.
8. Kubota R, Joshi N, Samandarova I, et al. Biometric changes associated with active stimulation of the peripheral retina with myopically defocused images in humans. Abstract from International Myopia Conference; 2022 Sep 4-7; Rotterdam, Netherlands.