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Refractive errors in 3-6 year-old Chinese children: a very low prevalence of myopia?
Weizhong Lan1, Feng Zhao, Lixia Lin
1State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, Guangdong, China.
Insights
This study found low myopia prevalence (≤2.5%) and high hyperopia prevalence (>20%) in Chinese children aged 3-6 years. Refractive error showed minimal age-related changes, suggesting a consistent early refractive development pattern.
Area of Science:
- Ophthalmology
- Pediatric Optometry
- Public Health
Background:
- Refractive errors are common in children and can impact visual development.
- Accurate measurement of refractive error in young children requires effective cycloplegia.
- Previous studies may have underestimated hyperopia and overestimated myopia due to inadequate cycloplegia.
Purpose of the Study:
- To determine the prevalence of myopia, hyperopia, and astigmatism in Chinese children aged 3-6 years.
- To analyze age-related changes in refractive error within this age group.
- To provide accurate data on early refractive development in a large pediatric cohort.
Main Methods:
- Cycloplegic refractions were performed on 2480 children aged 3-6 years in Guangzhou preschools.
- Refractions were measured using autorefraction and retinoscopy after administering 3-4 drops of 1% cyclopentolate.
- Standard definitions for myopia (≥-0.50 D), hyperopia (≥+2.00 D), and astigmatism (≥1.50 D) were applied.
Main Results:
- The mean spherical equivalent refractive error was +1.22 D.
- Prevalence of myopia was low (≤2.5%), while hyperopia prevalence exceeded 20% and slightly decreased with age.
- Astigmatism prevalence ranged from 6% to 11%, with minimal refractive error changes observed across the studied age range.
Conclusions:
- Adequate cycloplegia, potentially requiring up to 4 drops of cyclopentolate, is crucial for accurate pediatric refractive error assessment, especially in children with dark irises.
- The findings suggest a consistent pattern of early refractive development across ethnic groups, characterized by minimal myopia and a hyperopic mean spherical equivalent.
- These results provide a reliable baseline for understanding refractive error progression in early childhood.
Purpose:
To examine the prevalence of refractive errors in children aged 3-6 years in China.
Methods:
Children were recruited for a trial of a home-based amblyopia screening kit in Guangzhou preschools, during which cycloplegic refractions were measured in both eyes of 2480 children. Cycloplegic refraction (from 3 to 4 drops of 1% cyclopentolate to ensure abolition of the light reflex) was measured by both autorefraction and retinoscopy. Refractive errors were defined as followed: myopia (at least -0.50 D in the worse eye), hyperopia (at least +2.00 D in the worse eye) and astigmatism (at least 1.50 D in the worse eye). Different definitions, as specified in the text, were also used to facilitate comparison with other studies.
Results:
The mean spherical equivalent refractive error was at least +1.22 D for all ages and both genders. The prevalence of myopia for any definition at any age was at most 2.5%, and lower in most cases. In contrast, the prevalence of hyperopia was generally over 20%, and declined slightly with age. The prevalence of astigmatism was between 6% and 11%. There was very little change in refractive error with age over this age range.
Conclusions:
Previous reports of less hyperopic mean spherical equivalent refractive error, and more myopia and less hyperopia in children of this age may be due to problems with achieving adequate cycloplegia in children with dark irises. Using up to 4 drops of 1% cyclopentolate may be necessary to accurately measure refractive error in paediatric studies of such children. Our results suggest that children from all ethnic groups may follow a similar pattern of early refractive development, with little myopia and a hyperopic mean spherical equivalent over +1.00 D up to the age of 5-6 years in most conditions.
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