The article “Refractive Error and Ethnicity in Children”1 provides a unique set of longitudinal data regarding cycloplegic refractive error in American children. The cumulative distribution of spherical equivalent refractive error allows us to establish norms for refractive error in children, which has not been done in a robust manner in the United States before.
The definition of refractive error used in this study, however, is bothersome. The authors chose +1.0-diopter (D) and +1.25-D hypermetropia in each meridian to be the outcome measure for hyperopia. Accomodative amplitudes of children typically exceed 12 D,2,3 and therefore the choice of such an outcome value in the absence of strabismus or other symptoms is suspect. Providing the 95% cumulative distribution4 (ie, the value of hyperopia exceeded by 5% of children) and a table indicating the 90% and 98% cumulative distributions (ie, 10% and 2% of children) would probably be a better method of determining what is abnormal. The authors provide a cumulative distribution figure, but it is difficult to interpret from the figure.
Donahue SP, Baker J. Hyperopia: How Do We Define Abnormal?. Arch Ophthalmol. 2005;123(1):124-125. doi:10.1001/archopht.123.1.124-b