As the world faces a viral pandemic that has impacted almost every aspect of our lives, we are facing a pandemic of myopia as well. As eyecare professionals consider how to proactively address myopia, a number of controversies surrounding this topic need to be considered.

Efficacy

Currently, there are three evidence-based treatment strategies for myopia progression control (some off-label): overnight corneal reshaping/orthokeratology (ortho-k), daytime wear of distance-center multifocal contact lenses, and topical atropine therapy. Huang et al (2016) evaluated myopia management strategies using a meta-analysis of published randomized controlled trials. The studies cumulatively included 5,422 eyes and compared various treatment strategies, with placebo topical drops or single-vision spectacle lenses as controls. The authors concluded that a range of interventions can significantly reduce myopia progression when compared with single-vision spectacle lenses or placebo. The most effective were muscarinic antagonists such as atropine and pirenzepine. Certain specially designed contact lenses, including ortho-k and peripheral defocus-modifying lenses, had moderate effects, whereas specially designed spectacle lenses had minimal effect.

Sankaridurg et al (2018) looked at comparative efficacy of optical (spectacles, contact lenses, and ortho-k) and pharmaceutical approaches to slow myopia progression. They stated that all approaches can play a role in managing myopia, as needs of individual patients vary based on age, suitability, affordability, safety of the approach, subjective needs, and rate of progression. They also found that traditional spectacle lens approaches were inferior to ortho-k, multifocal contact lenses, and atropine therapy.

Efthymia et al (2019) evaluated 18 eligible studies involving 6,400 children; they found superior efficacy of atropine eye drop therapy, followed by ortho-k and novel multifocal contact lenses. The authors, however, emphasized the lack of long-term follow up in the studies reviewed.

Cheng et al (2019) presented a different perspective on myopia progression control efficacy, stating that it is best described as absolute rather than relative reduction in axial elongation across the progression range. Relative treatment effect slows over time, indicating that quoted percentage treatment estimates based on short-term effects are misleading. From their review and analysis of 56 studies reporting myopia control interventions, the projected best-case treatment effect for any individual undergoing myopia control over a seven-year period was 0.47mm, which is equivalent to little more than 1.00D.

More recent studies have looked at efficacy of specific treatment modalities. The LAMP (Low-Concentration Atropine for Myopia Progression) study reported that over two years, the efficacy of 0.05% atropine was double that observed with 0.01% atropine, and it remained the optimal concentration among the studied atropine concentrations in slowing myopia progression.

The Bifocal Lenses in Nearsighted Kids (BLINK) study compared the efficacy of distance-center multifocal soft contact lenses of +1.50D and +2.50D add powers to single-vision contact lenses (Walline et al, 2020). After three years, only the high-add lenses produced meaningful slowing of axial length. Research that led to the first U.S. Food and Drug Administration (FDA) approval of any treatment modality for myopia progression reported that wear of CooperVision’s MiSight soft multifocal lens produced a change in spherical equivalent refraction of –0.73D (59%) less in the test group than in the control group (P < 0.001), and the mean change in axial length (AL) was 0.32mm (52%) less in the test group than in the control group (P < 0.001) (Chamberlain et al, 2019).

Key new players in myopia management will likely come from novel spectacle lens designs. Lam et al (2020) evaluated the defocus incorporated multiple segments (DIMS) spectacle lens, currently available in Asia and Europe, in a two-year double-masked randomized controlled trial. Myopia progressed 52% more slowly for children in the DIMS group compared with those in the single-vision (SV) group, and the DIMS group had 62% less axial elongation compared to those in the SV group. In addition, 21.5% of children who wore DIMS lenses had no myopia progression over two years compared to only 7.4% of those who wore SV lenses.

Rappon et al (2020) presented, as an abstract, results from a multi-center randomized controlled double-masked clinical trial of a novel spectacle correction for myopia management utilizing reduced retinal contrast at the 2020 American Academy of Optometry meeting. At 12 months, the novel spectacle design significantly reduced cycloplegic refraction and AL progression (74% reduction in spherical equivalent refraction, 0.15mm reduction AL versus controls), and the investigational lenses were well-tolerated, both visually and cosmetically.

Interim findings of a study of a new spectacle lens for myopia management were reported at a recent virtual pediatric eye meeting (Essilor, 2020). At the one-year point of the three-year study, test subjects progressed 60% less versus controls.

Safety

When performing myopia management, risk management and balancing risks and benefits to patients are key. Bullimore et al (2013) evaluated the risk of microbial keratitis (MK) in ortho-k/corneal reshaping compared to other modalities of contact lens wear. This retrospective survey study concluded that the risk of MK with overnight corneal reshaping lenses is similar to that with other overnight modalities.

Liu and Xie (2016) published a more generalized look at multiple potential complications of ortho-k based on a review of the literature that incorporated 170 publications. The authors similarly found that the risk of MK in overnight ortho-k was similar to that of other overnight contact lens modalities. The most common complication was corneal staining. Other clinically insignificant side effects included epithelial iron deposit, prominent fibrillary lines, and transient changes of corneal biomechanical properties. There was no long-term effect of ortho-k on the corneal endothelium. They concluded that ortho-k is a safe option for myopia correction and retardation.

The safety of daytime soft multifocal lens wear would be the same as with wear of any daytime soft lenses. A literature review paper on the safety of soft contact lens wear in children reported that MK is rare; its incidence in children is not higher than it is in the adult population, and corneal infiltrative events in children are no higher than in adults. In the youngest age range of 8 to 11 years, corneal infiltrative events may be markedly lower (Bullimore, 2017). Additionally, Chamberlain et al (2019) reported no cases of serious ocular adverse events with daytime soft multifocal wear.

Regarding atropine therapy, it is well known that mydriasis and cycloplegia are concentration dependent. No key studies have reported any serious systemic or ocular side effects from topical atropine. Evidence supports the safety and efficacy of atropine therapy at concentrations of 1.0% and lower (Galvis et al, 2016). In the LAMP study, visual acuity and vision-related quality of life measurements remained unaffected with 0.05% atropine. Although photochromic lenses were needed for 30% of participants, no progressive lenses were necessary (Lam et al, 2020).

Safety was not a concern in the Rappon et al (2020) study of spectacle lenses for myopia management.

Gifford (2020) looked at the comparative lifetime risk of vision impairment with contact lens wear versus that from high myopia. She found that the comparative lifetime risks of lens wear initiated at age 8 for myopia control are less compared to the lifetime risks of vision impairment from myopia of more than 6.00D or axial length of more than 26mm.

Measuring Axial Length

As more eyecare practitioners embrace myopia management, the question arises as to which technologies are needed. The most common question is whether AL measurement should be required. For research studies, AL measurement is essential because it is a more accurate indicator of myopia progression and control (Wolffsohn et al, 2019). However, refractive myopia progression and AL elongation are significantly correlated (Chamberlain et al, 2019). If eyecare practitioners are to commit to measuring AL, then they need to use instrumentation with high accuracy and reliability. Wolffsohn et al (2020) reported that ultrasonography is limited in resolution to about 0.30D, compared to interferometry measurements, which have a resolution of around 0.03D. Obtaining multiple AL measurements reduces variability outcomes. Dillehay et al (2018) found that with the IOLMaster (software 5.0 or later, Zeiss), 20 measurements (versus five, 10, or 15) met the measurement error criteria of < 0.04mm or 0.125D. They felt that this protocol would provide clinicians with a sensitive method to assess whether observed refractive error changes present with concurrent AL changes. CLS

The authors acknowledge Kate Gifford, PhD, BAppSc(Optom)Hons, and Jeffrey Walline, OD, PhD, for their contribution to this article.

For references, please visit www.clspectrum.com/references and click on document #301.