Comprehensive eye exams and vision screenings are two methods used to detect amblyopia and other visual disorders in children. Eye exams are performed by an ophthalmologist or optometrist and are used to diagnose vision problems. Vision screenings are conducted by non-medical volunteers, nurses and pediatricians and used to identify people at risk for vision problems. The goal of the study was to estimate the impact and cost effectiveness of providing comprehensive eye exams to all preschool-age children. We compared the universal provision of eye exams to two interventions: (1) a system in which all preschool-age children receive a vision screening and (2) the eye care that would be provided to children even without the presence of a formal vision screening or eye exam program.