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Joseph M. Miller, Ryan G. Seltzer, Duane l. Sherrill, Erin M. Harvey, J.Daniel Twelker, Dawn H. Messer; Stability of Refractive Astigmatism in a Large Longitudinal Sample of Tohono O'odham Children. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2830.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the relative stability of refractive error components in a longitudinal sample of Native American pre-school and school-aged children belonging to a tribe (the Tohono O'odham) having a high prevalence of corneal astigmatism.
We combined data from three studies (NEI/NIH EY11155 (JMM), NEI/NIH 13153 (EMH) and NEI/NIH EY08893 (JDT) that examined 3387 children 3 years or older using an identical cycloplegic autorefraction protocol (Retinomax K-Plus, Nikon, now Right Mfg). This longitudinal database was stratified into subjects having no/low (<1D) and high (≥ 1D) refractive astigmatism in the right eye at baseline. A mixed-model program (Stata Corp, Version 11 analysis routine xtmixed) was applied to this data to determine the comparative predictors of slope, indicating stability of refraction.
At least one follow up examination was obtained on 2447 children. A total of 8481 refractions were obtained, with an average follow up of 2.65 years (SD 2.38, range = 0.23 to 11.25 years.) Dates of entry into the study ranged from 8/14/1997 - 5/17/2010. Average age at first measurement was 6.58 years (SD = 3.16, range = 3.00 - 16.3 yrs.) Average age at last follow-up measurement was 9.09 years (SD = 3.33, range = 3.49 - 17.07 yrs). Non-astigmatic children tended to remain non-astigmatic. The baseline refractive astigmatism of less than 1D decreased at a rate of -0.059 D/ Yr (p<0.0001). Astigmatism tended to decrease in the astigmatic children at a rate of -0.196 D/ Yr (p<0.001). The difference in rates between the two groups is statistically significant (p<0.0001).
A clinically small but statistically significant decrease in refractive astigmatism, averaging about 0.2 D/Yr, was observed among children having ≥ 1D refractive astigmatism at baseline. These data suggest that if a preschool or school-age Tohono O’odham child is screened and found to have little or no astigmatism they are likely to remain non-astigmatic. Conversely, if a child is found to require glasses for astigmatism, it is likely that they will continue to require eye care, for the rate of astigmatism regression is low.
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