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Prospective Observational Study of Ocular Health in International Space Station Crews (Ocular_Health)
Principal Investigator
Research Area:
Biomedical countermeasures
Cardiovascular physiology
Ocular physiological phenomena
Species Studied
Scientific Name: Homo sapiens Species: Human

The International Space Station (ISS) Ocular Surveillance protocol aims to systematically gather physiological data to characterize the Risk of Microgravity-Induced Visual Impairment and Intracranial Pressure (VIIP) on crewmembers assigned to a six month ISS Increment. The data collected will mirror Medical Requirements Integration Documents (MRID) requirements and testing performed during annual medical exams. The frequency of in-flight and post flight testing will be increased to more accurately assess changes that occur in the visual, vascular, and central nervous systems upon exposure to microgravity and induction of fluid shifting. Monitoring in-flight changes, in addition to post flight recovery, which is the main focus of this protocol.

The overall objectives of this study include the following:

  1. Characterize the nature of in-flight visual, vascular, and central nervous system changes during six months of exposure to microgravity.
  2. Document changes from pre- to post flight.
  3. Document changes post-flight, including the post flight time course for recovery to baseline.

This investigation hypothesizes that some crewmembers will experience meaningful and detectable changes before, during, and after space flight in at least one or more of the following measurements: visual acuity, intraocular pressure, optic disc edema, choroidal folds, optic nerve sheath distention, optic nerve tortuosity, optic nerve to sheath ratio, globe flattening, and retinal “cotton-wool spots.” Moreover, it is expected that crewmembers will have changes before and after in the Cerebrospinal fluid (CSF) velocity through the aqueduct of Sylvius and the retinal nerve fiber layer. It is further anticipated that measures observed during and after space flight will deviate from the baseline measurements, which may prolonged the recovery period to return to the baseline values.

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Giovanni T, Cromwell RL, Zanello SB, Yarbough PO, Ploutz-Snyder RJ, Bernard F. Godley BF, and Vizzeri G. Ocular outcomes comparison between 14- and 70-day head-down-tilt bed rest. Investigative Ophthalmology and Visual Science. 2016. February; 57(2): 495–501. [DOI]

Mader TH, Gibson CR, Otto CA, Sargsyan AE, Miller NR, Subramanian PS, et al. Persistent Asymmetric Optic Disc Swelling After Long-duration Space Flight: Implications for Pathogenesis. Journal of Neuro-ophthalmology. 2017. June 1; 37(2):133–9.

Blood pressure
Intracranial pressure
Intraocular pressure

Photo Gallery
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Data Information
Data Availability
Archiving in Progress. Some restricted access data exist for this experiment.
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Amsler grid
Aqueductal cross-sectional area
Average minimum rim width, global
Average peripappillary choroidal thickness, global
Blood pressure, diastolic
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Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 36 05/13/2013 09/10/2013 166 days
Expedition 37 09/10/2013 11/10/2013 61 days
Expedition 38 11/10/2013 03/10/2014 120 days
Expedition 39 03/10/2014 05/13/2014 64 days
Expedition 40 05/13/2014 09/10/2014 133 days
Expedition 41 09/10/2014 11/09/2014 29 days
Expedition 42 11/10/2014 03/11/2015 121 days
Expedition 43 03/11/2015 06/10/2015 91 days
Expedition 44 06/10/2015 09/11/2015 93 days
Expedition 45 09/11/2015 12/11/2015 91 days
Expedition 46 12/11/2015 03/02/2016 82 days
Expedition 47 03/02/2016 06/18/2016 108 days

Human Research Program (HRP) Human Research Roadmap (HRR) Information
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:

+ Click here for information of how this experiment is contributing to the HRP's path for risk reduction.

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Institutional Support
National Aeronautics and Space Administration (NASA)
Alternate Experiment Name
Proposal Date
Proposal Source