Prevalence of Amblyopia in School-Aged Children and Variations by Age, Gender, and Ethnicity in a Multi-Country Refractive Error Study.
OBJECTIVE
To estimate the age-, gender-, and ethnicity-specific prevalence of amblyopia in children aged 5 to 15 years using data from the multi-country Refractive Error Study in Children (RESC).


METHODS
Population-based, cross-sectional study.


METHODS
Among 46 260 children aged 5 to 15 years who were enumerated from 8 sites in the RESC study, 39 551 had a detailed ocular examination and a reliable visual acuity (VA) measurement in 1 or both eyes. Information on ethnicity was available for 39 321 of these participants. This study focused on findings from the 39 321 children.


METHODS
The examination included VA measurements, evaluation of ocular alignment and refractive error under cycloplegia, and examination of the external eye, anterior segment, media, and fundus.


METHODS
The proportion of children aged 5 to 15 years with amblyopia in different ethnic cohorts. Amblyopia was defined as best-corrected visual acuity (BCVA) of ≤20/40 in either eye, with tropia, anisometropia (≥2 spherical equivalent diopters [D]), or hyperopia (≥+6 spherical equivalent D), after excluding children with fundus or anterior segment abnormalities.


RESULTS
The overall prevalence of amblyopia was 0.74% (95% confidence interval, 0.64-0.83) with significant (P < 0.001) variation across ethnic groups: 1.43% in Hispanic, 0.93% in Chinese, 0.62% in Indian, 0.52% in Malay, 0.35% in Nepali, and 0.28% in African children. Amblyopia was not associated with age or gender. The most common cause of amblyopia was anisometropia.


CONCLUSIONS
In this study, the prevalence of amblyopia varied with ethnicity and was highest in Hispanic children and lowest in African children. Most cases were unilateral and developed before the age of 5 years. The impact of changes of definitions on prevalence estimates is discussed.
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Ou
O
Xiao
ARC Centre of Excellence in Vision Science and Research School of Biology, Australian National University, Canberra, Australia.
Ian G
IG
Morgan
National Eye Institute, National Institute of Health, Bethesda, Maryland.
Leon B
LB
Ellwein
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China; Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia. Electronic address: mingguang_he@yahoo.com.
Mingguang
M
He
D000293:Adolescent; D017677:Age Distribution; D000550:Amblyopia / Q000175:diagnosis / Q000208:ethnology*; D044466:Asian People / Q000208:ethnology; D044383:Black People / Q000208:ethnology; D002648:Child; D002675:Child, Preschool; D002677:Chile / Q000208:ethnology; D003430:Cross-Sectional Studies; D005006:Ethnicity; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D012029:Refraction, Ocular / Q000502:physiology; D017678:Sex Distribution; D014792:Visual Acuity / Q000502:physiology