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D. Robaei, A. Kifley, S.C. Huynh, J.M. Ip, K.A. Rose, P. Mitchell, Sydney Myopia Study, Sydney Childhood Eye Study; Correctable and Non–Correctable Visual Impairment in Two Representative Samples of Australian Children Aged 6 and 12 years . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1552.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the patterns of visual impairment in two population–based samples of Australian children aged 6 and 12 years, examined in 2003–5.
Logarithm of the minimum angle of resolution (logMAR) visual acuity was measured in both eyes unaided, with spectacles if worn, and after subjective refraction if required in 1740 younger (6–year–old) children and 2000 older (12–year–old) children. Cycloplegic autorefraction (with cyclopentolate) and detailed dilated fundus examination were performed. Using a cut–off of 0.3 logMAR units (<20/40), unaided and presenting visual impairment were defined by uncorrected and spectacle–corrected visual acuities, respectively. Myopia was defined as spherical equivalent refraction (SER) ≤–0.50 diopters (D), hyperopia as SER ≥+2.0D, anisometropia as SER difference ≥1.00D, and astigmatism as cylinder ≥1.0D. Amblyopia was defined as corrected visual acuity <0.3 logMAR not attributable to an underlying structural eye or visual pathway abnormality, together with a 2 logMAR–line difference between eyes.
Presenting visual impairment was found in the worse eye of 3.1% of younger children and comprised correctable (72%) and non–correctable impairment (28%). Correctable impairment was due to myopia in 6%, hyperopia in 31% and astigmatism in 63%. Non–correctable impairment was due to amblyopia in 87%, Coats’ disease in 13% and absent foveal pits in 13%. The corresponding rate of presenting impairment was 4.8% in the older age group, being 80% correctable and 20% non–correctable. Correctable visual impairment was due to myopia in 51%, hyperopia in 4%, astigmatism in 36%, and inappropriate spectacle prescription in 9%. Non–correctable impairment was due to amblyopia in 69%, congenital glaucoma in 13%, optic nerve hypoplasia in 13%, and cortical blindness in 6%. Prevalence of presenting impairment in the better eye was 0.9% and 1.1% for the younger and older groups, respectively, while unaided visual impairment in the worse eye was found in 4.1% of younger and 11.1% of older children. Corresponding rates in the better eye were 1.3% and 7.3%, respectively.
The prevalence of presenting visual impairment was similar in the two age groups, although the correctable proportion was slightly greater in the older than the younger age group, due to increasing myopia.
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