NASA’s Space Medicine Operations Division has given a name to the ocular responses which arise after long space journeys: space-flight associated neuro-ocular syndrome, or SANS.

The causes of SANS remain unknown, but NASA’s doctors have found that astronauts experienced unilateral and bilateral optic disc edema, globe flattening, choroidal and retinal folds, hyperopic refractive error shifts, and nerve fiber layer infarcts among other symptoms.

NASA’s study of SANS is ongoing, with further manned missions into space including both in-flight and post-flight intracranial magnetic resonance and imaging ocular optical coherence tomography.

In one study of long-duration space flights on the International Space Station (ISS), 12% of crewmembers reported decreased distant visual acuity, while 48% report decreased near visual acuity. Some of these refractive changed endured for years after the space flight.

Understanding the cause and developing countermeasures for SANS will be necessary for making longer duration manned trips, such as to the asteroid belt or Mars, NASA says.

Read the Special Communication at JAMA Ophthalmology HERE.