In 1994, the Visual Health Program of the State Social Enterprise, MetroSalud, created in 1991, accomplished its goal of performing complete optometric exams on all students 5-14 years of age (almost 350,000 children) enrolled in the public schools of Medellín and providing treatment to those children who needed it. In order to estimate the prevalence of visual disorders in this population group, a sample of 17,697 records from the Visual Health Program's database was selected randomly and analyzed. The sample represented 20% of the 88,485 children examined in 1993. The results indicated that 48% of the students in Medellín had refraction defects, which were slight in 8 out of 10 cases. The study also showed a 1.2% prevalence of amblyopia associated with more serious refraction defects, especially astigmatism. Rates of cataracts and glaucoma were 8.3 and 1.2 per 10,000, respectively.