Prevalence and associations of anisometropia and aniso-astigmatism in a population based sample of 6 year old children
- 1Centre for Vision Research, Department of Ophthalmology and Westmead Millennium Institute, University of Sydney, Sydney, Australia
- 2School of Applied Vision Sciences, Faculty of Health Sciences, University of Sydney, Sydney, Australia
- 3Vision Cooperative Research Centre, School of Optometry, University of New South Wales, Sydney, Australia
- Correspondence to: Paul Mitchell MD, PhD, FRCOphth, Centre for Vision Research, Department of Ophthalmology, University of Sydney, Hawkesbury Road, Westmead, NSW 2145, Australia; paul_mitchell{at}wmi.usyd.edu.au
- Accepted 4 January 2006
Abstract
Aim: To study the distribution of anisometropia and aniso-astigmatism in young Australian children, together with clinical and ocular biometry relations.
Method: The Sydney Myopia Study examined 1765 predominantly 6 year old children from 34 randomly selected Sydney schools during 2003–4. Keratometry, cycloplegic autorefraction, and questionnaire data were collected.
Results: Spherical equivalent (SE) anisometropia (≥1 dioptre) prevalence was 1.6% (95% confidence interval (CI) 1.1% to 2.4%). Aniso-astigmatism (≥1D) prevalence was 1.0% (CI: 0.6% to 1.6%). Both conditions were significantly more prevalent among moderately hyperopic (SE ≥2.0D) than mildly hyperopic (SE 0.5–1.9D) children. Myopic children (SE ≤−0.5D) had higher anisometropia prevalence. Neither condition varied by age, sex, or ethnicity. In multivariate analyses, anisometropia was significantly associated with amblyopia, odds ratio (OR) 29, (CI: 8.7 to 99), exotropia (OR 7.7, CI: 1.2 to 50), and neonatal intensive care unit (NICU) admission (OR 3.6, CI: 1.1 to 12.6). Aniso-astigmatism was significantly associated with amblyopia (OR 8.2, CI: 1.4 to 47), maternal age >35 years (OR 4.0, CI: 1.3 to 11.9), and NICU admission (OR 4.6, CI: 1.2 to 17.2). Anisometropia resulted from relatively large interocular differences in axial length (p<0.0001) and anterior chamber depth (p = 0.0009). Aniso-astigmatism resulted from differences in corneal astigmatism (p<0.0001).
Conclusion: In this predominantly 6 year old population, anisometropia and aniso-astigmatism were uncommon, had important birth and biometry associations, and were strongly related to amblyopia and strabismus.
- ACD, anterior chamber depth
- AL, axial length
- NICU, neonatal intensive care unit
- RA, refractive astigmatism
- SE, spherical equivalent
- VA, visual acuity
- population
- prevalence
- anisometropia
- Sydney Myopia Study
- Sydney Childhood Eye Study
- ACD, anterior chamber depth
- AL, axial length
- NICU, neonatal intensive care unit
- RA, refractive astigmatism
- SE, spherical equivalent
- VA, visual acuity
- population
- prevalence
- anisometropia
- Sydney Myopia Study
- Sydney Childhood Eye Study
Notes
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Competing interests: The authors have no financial interest in any materials used in this study.







