7. Project Summary Approximately 3.6 million concussions occur every year in the United States. The largest affected group is 11- to 18-year-olds, and the diagnosis of concussion in that age group is increasing. Children and adolescents are particularly vulnerable to the harmful effects of concussion because their higher-level cognitive functions are still developing. Although many adolescents fully recover from their concussion within four weeks, a significant number of adolescents have a prolonged recovery that may last weeks or even months. Common symptoms reported during the recovery from concussion are difficulty concentrating, blurred and/or double vision, losing one?s place when reading, and headaches. At least one vision disorder is reported to be present in 40-70% of adolescents with concussion. Persistent vision disorders during the recovery period are associated with decreased cognitive function and may be associated with prolonged concussion recovery. Despite the reported frequency of vision disorders in adolescents with concussion and the clear overlap in non-visual symptoms for concussion and vision disorders, it is still unclear what role vision disorders may play in the recovery process and their longer-term impact. Through two specific aims we will: 1) Demonstrate feasibility of high participant accrual and retention rates at 10-day, one-month, and three-month visits in concussed adolescents and in a concurrent group of non-concussed adolescents for comparative purposes; and 2) Optimize our vision test battery and develop a comprehensive manual of procedures for our natural history study on vision disorders in adolescents with concussion. Our long-term goal is to conduct a future multi-center, multidisciplinary natural history study to inform the healthcare community about vision disorders and their association with cognitive abilities throughout the recovery process.