The problem of screening children for visual defects.

All the cases of squint and amblyopia referred to both hospital and school clinics in one district during one calendar year have been reviewed in order to clarify when, where, and how these cases first present to the ophthalmologist. The types of case at present seen in "hospital" and "school" clinics are quite different, and effective screening methods are unlikely to be developed if these two services continue to be regarded as separate entities. Exotropia is much less frequent than esotropia (only 15% of all cases of squint). The concept of a single peak number of first attendances of children with esotropia at age 3 to 4 years is not substantiated. There is a second peak at age 5 years, when children first go to school. In fact 49% first attended after their fifth birthday. The majority (69%) of cases of amblyopia presented after the age of 5 years. Three-quarters of these (46% of the total) have no clinically detectable squint. Neither they, nor those children who have a strabismic amblyopia, but not a cosmetically noticable squint, will at present be detected until they have a sight test at school. This is a measure of the need to re-examine our long-established methods of screening children for amblyopia. One screening test designed to identify both the "squinter" and the "straight-eyed amblyope" is required.