School-based vision screening in Quetta, Pakistan: a qualitative study of experiences of teachers and eye care providers.

School-based vision screening by teachers is a cost-effective strategy to detect and treat children's vision impairment early on. In the programme reviewed here however, a significant number of teachers over referred children to ophthalmic services, overwhelming their capacity and undermining the efficiency of the approach. To maximise the effectiveness and efficiency of school-based screening, future initiatives should give sufficient attention to the duration of the teacher training, experience of trainers, support supervision, refresher trainings, regular use of the screening guidelines, and the workload and motivation of those trained.