Epidemiology of myopia and prevention of myopia progression in children in East Asia: a review

Methodological quality of the review: Low confidence

Author: CY Mak, Jason CS Yam, LJ Chen, SM Lee, Alvin L Young

Region: Hong Kong or East Asia

Sector: Myopia

Subsector: Epidemiology of myopia and prevention

Equity focus:Children

Study population: Children

Type of programme: Therapeutic intervention

Review type: Other review

Quantitative synthesis method: Systematic review

Qualitative synthesis method: Not applicable

Background: Myopia is a refractive disorder in which distant light entering a non-accommodating eye is focused in front of, rather than on, the retina. Myopia is categorised as axial or refractive myopia. Myopia is a prevalent eye disorder in children and adolescents in Hong Kong, which requires the use of spectacles or contact lenses for optimal vision. The complications of high myopia can be vision threatening; therefore, clinicians and parents have great interest in controlling myopia progression in children, which may prevent the complications of myopia that can occur in adulthood.

Objectives: To examine recent publications regarding myopia epidemiology and interventions for controlling myopia progression in children.

Main findings: Regional epidemiology: The current epidemic of myopia is well-known in the developed countries of East Asia. A high prevalence of myopia has been reported by many countries with populations of Chinese ancestry. Additionally, there is a high prevalence of myopia in Hong Kong children: 18.3% at 6 years of age and 61.5% at 12 years of age; the prevalence of high myopia (greater than -6.0 D) in the same cohort of Hong Kong children was 0.7% at 6 years of age and 3.8% at 12 years of age.
Regional population genetics: Genetic loci associated with myopia in the Hong Kong Chinese include PAX6, ZFHX1B, VIPR2, SNTB1, TGIF, 13q12.12, and 5p15. The roles of these genes and loci in myopia pathogenesis and clinical manifestation are not yet known.
Complications of myopia: Myopia is associated with a wide range of complications, many of which are vision-threatening and may cause blindness. Pharmacological agents to control myopia progression: Atropine eye drops and pirenzepine eye gel are highly effective for controlling myopia progression in children. Orthokeratology, peripheral defocus contact lenses, bifocal or progressive addition spectacles and increased involvement in outdoor activities are also effective for controlling myopia progression; however, myopia under-correction and single vision contact lenses are ineffective.

Methodology: Inclusion criteria consisted of: 1) studies involving myopia epidemiology and control of myopia progression were selected; only studies published in English were reviewed. In the selection of representative articles for each therapeutic intervention to control myopia progression, prospective studies were ranked higher than retrospective studies. Among prospective studies, preference was given to randomised and controlled trials, as well as studies conducted in Hong Kong or East Asia. Authors performed a literature search using PubMed from the date of inception through to 25 June 2018.

Applicability/external validity: Not discussed.

Geographic focus: Not discussed.

Summary of quality assessment:

Overall, this review was attributed low confidence, as important limitations were identified. Authors did not provide detailed information on the methods to conduct this review, therefore findings should be analysed with caution.