Optic Nerve Length before and after Spaceflight

PurposeThe spaceflight-associated neuro–ocular syndrome (SANS) affects astronauts on missions to the International Space Station (ISS). The SANS has blurred vision and ocular changes as typical features. objective of this study was investigate if microgravity can create deformations or movements eye optic nerve, such could be linked SANS.DesignCohort study.ParticipantsTwenty-two (age 48 ± 4 years).MethodsThe intervention consisted time in at ISS. We co-registered pre- postspaceflight magnetic resonance imaging (MRI) scans generated centerline representations nerve. coordinates for nerve head (ONH) chiasm (OC) ends were recorded along with entire path.Main Outcome MeasuresOptic length, ONH movement, OC movement after microgravity.ResultsOptic length increased (0.80 0.74 mm, P < 0.001), primarily reflecting forward displacement (0.63 0.53 0.001). positively related mission duration, preflight body weight, clinical manifestations SANS. also detected upward (0.39 0.50 = 0.002), indicative brain but observation not SANS.ConclusionsThe spaceflight-induced lengthening anterior support that is caused by an altered pressure difference between eye, leading a push posterior eye. Body weight potential contributing risk factor. Direct assessment intracranial space required verify implicated mechanism behind findings Cohort study. Twenty-two years). path. Optic microgravity.