The past two decades have seen an increase in interest and activity in vision screening of preschool children, an effort directed toward the detection of treatable eye defects, especially amblyopia. Articles written for the lay public have recently been challenged for accepting a falsely high incidence of amblyopia, and the value of early detection of amblyopia has been questioned.1
Variations in the reported incidence of amblyopia are traceable to many factors, including the sample screened, the test used in screening, and the criterion adopted for the definition of amblyopia.
Studies of military and clinic populations project a falsely high indication of the incidence of amblyopia at most levels of its definition.2 Studies with isolated letters or characters minimize the difference in acuity between an individual's two eyes in comparison with the same letters or characters arranged in lines on a chart. Small differences detected by single targets are,
INCIDENCE OF AMBLYOPIA. JAMA. 1967;199(3):211. doi:10.1001/jama.1967.03120030115024