High corneal astigmatism in Navajo school children and its effect on classroom performance.

809 unselected Navajo school children from kindergarten to sixth grade received visual acuities and keratometry readings. The information obtained was directed at statistical analysis of the degree of corneal curvature of two diopters or more and the distribution of its ranges, grade distribution, sex distribution, unilateral percentage and eye dominancy, uncorrected visual acuities of the high uncorrected astigmat, the mean corneal astigmatism, and the relationship between uncorrected high astigmatism and classroom performance.