ABSTRACT
The UK Amblyopia Treatment Trial (ATT) is a randomised single blind controlled trial of treatment for unilateral visual acuity deficit detected at pre school vision screening (PVS). Screening is the testing of apparently well people in order to uncover those at increased risk of having a disease or disorder. Vision screening of schoolchildren started in the UK in 1908 as it was thought that defective vision impeded education. The sensitive period for visual development was identified in animal experiments and since then there has been an emphasis on early detection and treatment of amblyopia. A year later a systematic review of PVS reported a poor evidence base for the success of treatment and recommended that a RCT of treatment versus no treatment be undertaken. The ATT was developed to address the issue of treatment versus deferred treatment for the main screening target condition ‘straight-eyed amblyopia’.
