Visual acuity testing in young children.

Various tests are in common use for determining the visual acuity (VA) in children, and this paper reports the results of an investigation into some of them in regard to their accuracy, acceptability, and comparability. Early assessment of the VA is desirable in order to detect any abnormality, but through lack of co-operation and comprehension, it cannot usually be carried out until the age of 31 years. Visual tests used for children younger than this are based on the responses elicited by an object that can just be perceived, such as small white balls on a black background (Sheridan, I969), sugar balls, "hundreds and thousands" (Keith, I968), or opticokinetic nystagmus (Lewkonia, I969), but such tests are not comparable with acuity tests because they measure a much lower degree of vision; the former are testing only the minimum visible while the latter may not be testing the foveal vision at all. Extensive studies have been carried out by Pugmire and Shexidan (1957, i960) and Sheridan (i960, i963, I969) on visual tests suitable for young children and retarded children, and as a result they developed the Stycar vision tests, the single letter part of which has been included in this survey.