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D. H. Messer, J. M. Miller, V. Dobson, E. M. Harvey; Relation Between Level of Astigmatism and Changes in Refractive and Corneal Astigmatism Over a Period of 2 Years. Invest. Ophthalmol. Vis. Sci. 2009;50(13):3969.
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© ARVO (1962-2015); The Authors (2016-present)
To examine the relation between level of astigmatism and changes over 2 years in refractive and corneal astigmatism in preschool members of a Native American Tribe.
Subjects were 87 children attending the Tohono O’odham Nation’s Head Start program, who had cycloplegic autorefraction and autokeratometry measurements taken with the Nikon Retinomax K-Plus and repeated at least 2 years later. Children were excluded if they had any ocular anomalies or if measurement confidence level was below 8 on the Retinomax at baseline or follow-up. For analysis, only data for the right eye of each subject were used. Subjects with more than 1.50D of refractive astigmatism (RA) at baseline were classified as having high astigmatism, while those with 1.50D or less RA were classified as having low astigmatism.
Mean age of subjects was 4.1 (0.51SD) years at baseline, and 6.5 (0.54SD) years at follow-up, with a range of follow-up from 2.0 to 2.7 years. Mean RA of the entire cohort did not significantly change from baseline (T1) to follow-up (T2), with only 16% of subjects having a change in refractive astigmatism of greater than 0.5D. However, in subjects with high astigmatism, mean RA increased over time, with 25% increasing by more than 0.5D and none decreasing by more than 0.5D. In low astigmats, mean RA decreased, with RA decreasing by more than 0.5D in 10% and only increasing by more than 0.50 in 1 subject. Similarly, mean corneal astigmatism (CA) did not significantly change for the population as a whole, but CA increased in high astigmats and decreased in low astigmats. See Table.
Consistent with other studies, we found the power of both RA and CA to be reasonably stable over time. However, in children with high astigmatism, RA and CA were likely to increase over time, whereas children with low astigmatism were more likely have their astigmatism decrease.
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