Study Finds Cause of Visual Impairment in Astronauts

New research presented today at RSNA 2016 shows the strong positive relationships between globe deformations and cerebrospinal fluid (CSF) volume increases without changes to brain volumes, indicating CSF has a direct role in spaceflight-induced ocular changes. Vascular fluid shift has a lesser role than CSF in microgravity diced visual impairments and ocular changes syndrome.

Ocular and vision changes known as visual impairment intracranial pressure (VIIP) syndrome have been reported in nearly two thirds of long-duration mission International Space Station (ISS) astronauts.

Noam Alperin, PhD, of the University of Miami Miller School of Medicine, and colleagues measured and compared high-resolution orbit and brain MRI scans before and shortly after spaceflights for seven long-duration mission ISS astronauts and nine short-duration mission Space Shuttle astronauts.

Post flight increases in globe flattening and nerve protrusion were tested for association with increases in intra-orbital CSF volume, ventricular CSF volume, and brain tissue interstitial fluid volume.

Compared to short-duration astronauts, long-duration astronauts had significantly greater post-flight increases in globe flattening indices and optic nerve protrusion indices. Long-duration astronauts also had significantly greater post flight increases in orbital CSF volume and ventricular CSF volume.

“Identifying the origin for the space-induced ocular changes is necessary for the development of countermeasure to protect the crew from the ill effects of long-duration exposure to microgravity,” the authors write.