Pre-school vision study.
D002675:Child, Preschool; D005133:Eye Movements; D005260:Female; D005654:Fundus Oculi; D006801:Humans; D008297:Male; D009801:Oculomotor Muscles; D009887:Ophthalmoscopy; D012029:Refraction, Ocular; D012578:Schools, Nursery; D013285:Strabismus / Q000453:epidemiology; D014787:Vision Tests / Q000295:instrumentation*; D014792:Visual Acuity; D014852:Wales