Myopia Control With Specialized Spectacles: JAMA
Children aged 8 to 14 years with mild to moderate myopia (-0.75-diopters [D] to-4.75-D spherical equivalent refraction) randomly assigned to wear slightly aspherical lenslet (SAL) or highly aspherical lenslet (HAL) spectacles showed less myopic progression than those who wore single-vision spectacle lenses. In addition, the HAL wearers showed less progression than the SAL wearers.
The authors David C. Musch and team powered their study to detect a 33% reduction in the amount of spherical equivalent refraction and axial length progression, and they enrolled 170 children, 20 more than the 150 (50 per group) required to provide adequate power. They analyzed the 2-year, right-eye findings of 157 children (92.4%) and describe the reasons for lack of follow-up well. After 2 years of follow-up, children who wore the HAL or SAL spectacles had 0.80 D and 0.42 D less myopic progression, respectively, than wearers of single-vision spectacle lenses, with corresponding axial length findings.
Although the authors only analyzed information from the right eye-thus sacrificing the additional statistical power of using both eyes with appropriate treatment of the intereye correlation3-the statistical significance of their findings is clear. What remains to be considered is the clinical relevance of their findings and the feasibility of having children wear spectacles with aspherical lenslets for many years. Given the children's mean (SD) age at enrollment of 10.6 (0.2) years, with much of their period of rapid myopic progression behind them, one wonders how much additional benefit would occur beyond 2 years.
However, would younger children adhere well to wearing spectacles with glare from the edges of the lenslets and degraded vision through the aspheric portion of the lens when the child's gaze wanders away from primary position? Wear time in this study was moderately worse for aspheric lenses, with approximately 58% of the HAL and SAL groups vs 68% of the single-vision spectacle lens group having worn their spectacles for at least 12 hours per day. The fact that the mean daily wear time increased from the first to second year in the HAL and SAL groups suggests that the children adjusted well to these lenses, but this may not be the case for younger children, and therefore, there is a need to study this further. Given that rebound has been an issue after pharmacological methods for myopia control, what would happen should the aspheric spectacles be discontinued requires study as well.
The authors adjusted for baseline age, sex, spherical equivalent refraction, axial length, age at myopia onset, and number of parents with myopia in their linear mixed model, as these are factors that may influence myopic progression, but it would be of interest to see whether, eg, myopic progression in children with more substantial myopic error at baseline (eg, 5.0 D or greater) differed from those with minimal baseline myopia. This may become relevant with longer-term follow-up, as preventing a child from becoming highly myopic in adulthood may be more important than intervening in a child with 1.0 D of myopia to limit progression to 3.0 D in adulthood. This is because many of the more serious complications of myopia, such as retinal detachment and myopic maculopathy, occur especially in adults with high myopia who may be genetically distinct5 from those with low myopia and have a different biological response to myopia control measures.
The clinical relevance of these findings may also be influenced by factors unique to the population being studied. The prevalence of myopia and high myopia among Asian populations is much higher than that in Western populations, which may reflect genetic or environmental differences that could affect the response to wearing spectacles with aspherical lenslets. Differences may exist across populations, as well, in the likelihood of adhering to wearing spectacles, given possible differences across populations in the degree to which parents are reluctant to have their child wear spectacles.
The authors have presented evidence from a well-designed randomized clinical trial that wearing spectacles with aspherical lenslets, particularly those with a higher degree of asphericity, reduces progression of myopia over 2 years of wear time. Although many remaining questions need to be addressed before recommending HAL spectacles for routine use in childhood, conducting such trials is critical to identify interventions that are both effective and feasible to control myopia, which has been aptly termed "the silent epidemic that should not be ignored."
Source: David C. Musch, PhD, MPH; Steven M. Archer, MD; JAMA Ophthalmology
doi:10.1001/jamaophthalmol.2022.0533
