Expanding myopia epidemic likely to result in increasing prevalence of pathologic myopia
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The expanding myopia epidemic and the increasing number of children who develop myopia at a young age will likely result in increased prevalence of pathologic myopia in the future.
“A key feature of the current myopia epidemic is a younger age at onset. This could result in a longer time for progression prior to stabilization in adulthood and in an even higher prevalence of high myopia in the future,” Timothy Y.Y. Lai, MD, and Danny S.C. Ng, MPH, wrote in an invited commentary published in JAMA Ophthalmology.
The expanding myopia epidemic and the increasing number of children who develop myopia at a young age will likely result in increased prevalence of pathologic myopia in the future.
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High myopia is linked to pathologic myopia, a leading cause of visual impairment in East Asian countries and now a growing concern in other parts of the world, including the United States and Europe. In a cross-sectional study, Haarman and co-authors reported the prevalence of myopic macular features in individuals of European ancestry with high myopia included in the Rotterdam Study and the Dutch Myopia Study. The frequency of myopic macular degeneration in the pooled cohort was 25.9%. Prevalence increased with age, but also in younger people, myopic macular degeneration was not rare. It occurred in 9.2% of individuals with high myopia in the 20 to 29 years age group, in 10.6% of those aged 30 to 39 years, and 25% of those aged 40 to 49 years.
Consequences of axial elongation
Several theories have been advanced to explain the mechanisms that drives the onset of pathological changes in eyes with high myopia.
“The most important is the mechanical theory, in which axial elongation of the globe can lead to breaks in the retinal pigment epithelium-Bruch’s membrane-choriocapillaris complex and thinning of the choriocapillaris, causing myopic chorioretinal atrophy and choroidal neovascularization. Moreover, axial elongation with posterior staphyloma can lead to vitreomacular interface abnormalities causing myopic traction maculopathy,” Lai told Healio/OSN.
Axial length continues to increase in adults with high myopia, and it is therefore important to regularly monitor highly myopic eyes to detect changes as early as possible and promptly provide treatment, he said.
Fundus photography, OCT, OCT angiography (OCTA), fluorescein angiography (FA) and indocyanine green angiography (ICGA) are useful multimodal imaging tools to detect the changes associated with pathologic myopia.
“For example, thinned choroid and myopic traction maculopathy can be evaluated by OCT. Myopic CNV can be evaluated by OCT, OCTA and FA, while changes like lacquer cracks can be documented by fundus photography and ICGA. Imaging can also be used to assess the development of glaucoma in high myopic eyes,” Lai said.
In cases with myopic choroidal neovascularization (CNV), intravitreal anti-VEGF injection is the standard of care. For cases with progressive myopic traction maculopathy, including myopic foveoschisis with foveal detachment and myopic macular hole, vitrectomy with internal limiting membrane peeling surgery is required.
Prevention is priority
The rapid surge of high myopia and its complications could result in a significant health care burden in future years. Prevention should therefore become a priority through frequent, regular screening programs for the detection and monitoring of refractive error in school-aged children and teenagers. In case of visual problems, they should be promptly referred to an eye care professional for treatment.
“In addition, since increased time spent indoors, near work and screen time have been linked with younger age of onset in myopia and myopia progression, interventions should include lifestyle changes, such as more time spent outdoors during school hours,” Lai said.
Unpreserved low-dose atropine and optical defocus treatment have both been shown to be effective strategies to reduce the progression of myopia and should be considered in high-risk children in order to prevent the development of pathological changes associated with high myopia.
The COVID-19 pandemic has led to prolonged periods of school closure in many countries. Children have been spending less time outdoors, and online learning has further increased the time they spend on screens.
“Multiple studies, including studies in Hong Kong, mainland China and India, have shown that the incidence of myopia has increased considerably during the COVID pandemic, with faster rates of axial length elongation,” Lai said.
It will be important in future years to raise awareness on the importance of myopia control and implement interventions.
“School screening programs and clinical trials will help identify additional risk factors and potential new interventions for myopia development and progression, which hopefully will lead to the development of more effective preventative and treatment strategies,” Lai and Ng wrote in their commentary.
References:
- Haarman AEG, et al. JAMA Ophthalmol. 2022;doi:10.1001/jamaophthalmol.2021.5346.
- Ng DSC, et al. JAMA Ophthalmol. 2022;doi:10.1001/jamaophthalmol.2021.5347.
For more information:
Timothy Y.Y. Lai, MD, can be reached at the Chinese University of Hong Kong, Hong Kong Eye Hospital Department of Ophthalmology & Visual Sciences, 147K Argyle St., Kowloon, Hong Kong, People’s Republic of China; email: tyylai@cuhk.edu.hk.
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