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Ophthalmic and Intracranial Structural Changes in Head-down Tilt Bedrest: Potential Countermeasures and Comparison to SANS Findings in Astronauts (OPTICS Study) (80NSSC20K0920)
Principal Investigator
Research Area:
Biomedical countermeasures
Ocular physiological phenomena
Species Studied
Scientific Name: Homo sapiens Species: Human

Space flight associated neuro-ocular syndrome (SANS) is a combination of pathological ophthalmic findings that have been documented in a subset of astronauts that participated in long-duration missions (6+ months) to the International Space Station (ISS). The leading hypothesis for SANS is that the lack of a gravitational vector acting on the body results in a headward body fluid shift that can lead to damage to the eye. Recent research has revealed multiple structural changes in the eye and brain that occur in astronauts with SANS. To help mitigate these structural changes, it is imperative to validate a ground-based analog for spaceflight which can reproduce the structural and physiological changes observed in astronauts.

This experiment will use non-invasive magnetic resonance imaging (MRI) and optical coherence tomography (OCT) to quantify structural and physiologic changes in the brain and eye that occur in prolonged six-degree head-down tilt (HDT) and examine if these alterations can be mitigated using countermeasures.

The experiment includes three specific aims.
(1) Quantify ophthalmic and intracranial alterations in HDT bed rest subjects and postural control subjects compared to pre-bed rest.
(2) Determine if countermeasures can prevent and/or reduce HDT bed rest-induced cerebral and ocular alterations.
(3) Compare alterations in HDT subjects to those already quantified in astronauts that developed SANS.

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Optic nerve
Retinal vessels
Cerebrospinal fluid

Data Information
Data Availability
Archiving in progress. Data is not yet available for this experiment.

Jugular venous outflow
Aqueduct of Sylvius stroke volume
Blood flow volume
Brain tissue volume, gray matter
Brain tissue volume, white matter
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Ground 05/01/2009 In Progress

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Institutional Support
National Aeronautics and Space Administration (NASA)
Proposal Date
Proposal Source
2018-2019 HERO 80JSC018N0001-SANS: Spaceflight Associated Neuro-ocular Syndrome Countermeasures. Appendix C