AAPOS is the American Association for Pediatric Ophthalmology and Strabismus. To be an active member of AAPOS, a Pediatric Ophthalmologist has to complete one or two additional years of approved fellowship training following a three-year residency in comprehensive ophthalmology. Members are certified by the American Board of Ophthalmology.  A pediatric ophthalmologist devotes at least 75% of his/her practice to the treatment of children, and of adults with strabismus.