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Astigmatism and its components in 6-year-old children
Son C Huynh1, Annette Kifley, Kathryn A Rose
1Centre for Vision Research, Department of Ophthalmology, and the Westmead Millennium Institute, University of Sydney, Sydney, Australia.
Investigative Ophthalmology & Visual Science
|December 31, 2005
Summary
Refractive astigmatism (RA) and corneal astigmatism (CA) prevalence in 6-year-olds was low but varied by ethnicity. Emmetropization appears to involve a balance between CA and internal astigmatism (IA).
Area of Science:
- Ophthalmology
- Pediatric eye health
- Refractive error research
Background:
- Astigmatism is a common visual impairment affecting refractive development.
- Understanding astigmatism prevalence and types in young children is crucial for early intervention.
- The Sydney Myopia Study investigates refractive and eye health in a pediatric population.
Purpose of the Study:
- To determine the prevalence of refractive astigmatism (RA), corneal astigmatism (CA), and internal astigmatism (IA) in 6-year-old children.
- To analyze how RA, CA, and IA vary with gender, ethnicity, and refractive status.
- To explore the interplay between CA and RA in relation to gender, ethnicity, and spherical equivalent refraction.
Main Methods:
- Population-based survey of 6-year-old children in Sydney, Australia (2003-2004).
- Utilized a random cluster sampling design for participant recruitment.
- Collected data through questionnaires and comprehensive eye examinations, analyzing keratometric and cycloplegic autorefraction data from right eyes.
Main Results:
- Prevalence: RA 4.8%, CA 27.7%, IA 21.1% (≥1.0 diopter).
- Astigmatism axis distribution varied: RA (oblique), CA (with-the-rule), IA (against-the-rule).
- Girls showed slightly higher mean CA and IA. East/South Asian children had higher RA/CA prevalence than European Caucasians. RA and CA increased with myopia and hyperopia; IA increased with hyperopia.
Conclusions:
- Astigmatism prevalence in 6-year-olds is relatively low, with significant ethnic variations observed.
- Emmetropization in refractive astigmatism appears to be a compensatory mechanism between corneal and internal astigmatism.
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