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John Twelker, Joseph Miller, Dawn Messer, Erin Harvey; The Magnitude and Symmetry of Refractive and Corneal Astigmatism in Children. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5962.
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© ARVO (1962-2015); The Authors (2016-present)
To describe the magnitude and symmetry of corneal and refractive astigmatism in a group of Native American children.
Subjects were 1717 participants in one or more NIH/NEI funded studies of visual development in Tohono O’odham children (“Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error”(CLEERE, Tucson Site), “Astigmatism and Amblyopia Among Native American Children”, “Amblyopia in Astigmatic Children: Development and Treatment”). Previous research has documented a high prevalence of with-the-rule astigmatism in this population. A baseline exam was conducted and follow-up exams were attempted at least yearly for each study, and data was combined across studies. Cycloplegic autorefraction and autokeratometry (RetinomaxAutorefractor (KPlus or KPlus2, Nikon Inc., Tokyo Japan) were conducted at each study exam. Subject exams that met the following criteria were included in analyses: follow-up of at least one year, right and left eye autorefraction confidence ≥ 8, and only data from each child’s baseline and final study exams. The corneal and refraction measurements were converted to M, J0, and J45 Fourier-transformed vectors for data analysis.
The mean age at the baseline exam was 6.07 years, and at the last examination was 10.48 years. The mean follow-up time was 4.42 years, with a minimum of 1.00 and maximum of 14.42 years. At baseline, in the right eye, 636 (37%) had refractive J0 astigmatism of 0.50 or greater and 337 (19.6%) had J0 astigmatism 1.00 or greater. At baseline, mean refractive astigmatism for the right eye was J0=0.53 and J45=0.03, and for the left eye was J0=0.54 and J45=-0.04. For the right eye, change per year was statistically significant for refractive astigmatism J0 and J45, and for corneal astigmatism J0 and J45. However, in all cases, mean change was very small (< 0.02D/year) and not clinically significant. When refractive astigmatism was present (J0≥0.50), 245 (46.0%) showed a V-pattern symmetry in axis, and 108 (19.5%) showed an A-pattern symmetry in axis, with similar results for corneal astigmatism.
In this Native American group of children, moderate to high astigmatism was common. The refractive and corneal astigmatism was stable over time. When astigmatism was present, almost two-thirds showed symmetry in axis between eyes.
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