Space Flight-associated Neuro-ocular Syndrome（SANS）

Abstract

　Astronauts have been reported to experience abnormalities, such as optic disc edema, globe flattening, and associated hyperopia and choroidal folds due to spaceflight. The National Aeronautics and Space Administration（NASA）had confirmed the incidence of intracranial hypertension in addition to eye abnormalities in astronauts; hence, these problems were once collectively referred to as visual impairment and intracranial pressure syndrome（VIIP）. Subsequently, astronauts experiencing ocular abnormalities without intracranial hypertension were confirmed; therefore, NASA has changed the collective term for these spaceflight-related abnormalities from VIIP to space flight-associated neuro-ocular syndrome（SANS）and focused on the search for the cause and treatment of SANS. Recently, astronauts staying in space for a long time have been reported to keep their brains shifted upward after their return from space and the Bruch’s membrane opening of the optic disc is pulled towards the brain.

　In addition, using magnetic resonance imaging, the total volume of the ventricular system has been found to increase after a prolonged stay compared to that at the pre-flight level. This paper introduces the ocular changes due to spaceflight based on various reports.