Abstract

The purpose of the study was to measure the distribution of phorias among children. Vertical and horizontal phorias were measured at far and at near among (N = 2048) 6-13-yr old children. Kolmogorov-Smirnov goodness of fit tests showed that horizontal phoria at near (D = 6.76) and at far (D = 9.84) and vertical phoria at near (D = 20.59) and at far (D = 17.81) were not distributed normally. Results also showed that the data were not skewed. Sign tests gave identical results. The sample was divided into nine groups according to age. Krus- kall-Wallis one-way ANOVAs showed that horizontal phoria at near (X² = 8.52) and at far (X² = 14.78) and vertical phoria at near (X² = 3.78) and at far (X² = 17.52) did not vary with age. Scheffe's S ANOVAs also showed that horizontal phoria at near (F = 1.24) and at far (F = 1.28) and vertical phoria at near (F = 1.39) and at far (F = 2.17) did not vary with age. Orthophorization of vertical phoria appears at least at age 6 and no variation of phoria with age seems to appear before puberty. Comparisons of any individual findings with the general distribution curve should take the nonGaussian distribution of phorias into account. Moreover, nonparametric methods would be more appropriate since the distribution of phorias is non-Gaussian at least among children.

© 1989 Optical Society of America