Expedition 47 Commander Tim Kopra of NASA participates in the Ocular Health investigation aboard the International Space Station. The study seeks to help researchers better understand microgravity-induced visual impairment and changes believed to arise from elevated intracranial pressure. These tests will help characterize how living in microgravity can affect the visual, vascular and central nervous system. The investigation will also measure how long it takes for astronauts to return to normal after they return to Earth.