OBJECTIVES:
In humans exposed to up to approximately six months of weightlessness, altered visual acuity and structural adaptions of the ocular system have developed, including hyperopic shifts, choroidal folds, and optic disc edema. While the etiology and progression of vision impairment and intracranial pressure (VIIP)/Spaceflight Associated Neuro-ocular Syndrome (SANS) are not yet clearly defined, given the potential implications for mission success and long-term health, potential countermeasures are being investigated in parallel with definition of VIIP/SANS mechanisms. To prepare for future exploration missions, efforts currently are directed to identify factors that contribute to the ocular structural and functional changes in parallel with evaluating possible countermeasures using ground-based analogs of weightlessness. Given that the headward fluid shift associated with weightlessness has been hypothesized to be one of the central contributors to VIIP/SANS, countermeasures that reverse the headward fluid shift, such as those that trap fluid in the legs or lower body, may have the greatest promise. The goal of this project was to determine if venoconstrictive thigh cuffs used during acute head-down tilt (HDT), a space flight analog, mitigate changes in intracranial pressure (ICP), ocular, and intraocular pressure (IOP) associated with a cephalad fluid shift.

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Crew health and performance is critical to successful human exploration beyond low Earth orbit. The Human Research Program (HRP) investigates and mitigates the highest risks to human health and performance, providing essential countermeasures and technologies for human space exploration. Risks include physiological and performance effects from hazards such as radiation, altered gravity, and hostile environments, as well as unique challenges in medical support, human factors, and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify the approach and research activities planned to address these risks, which are assigned to specific Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.

The Human Research Roadmap is located at: https://humanresearchroadmap.nasa.gov/