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Numerical Modeling of Ocular Dysfunction in SpaceUpon introduction to microgravity, the near-loss of hydrostatic pressure causes a marked cephalic (headward) shift of fluid in an astronaut's body. The fluid shift, along with other factors of spaceflight, induces a cascade of interdependent physiological responses which occur at varying time scales. Long-duration missions carry an increased risk for the development of the Visual Impairment and Intracranial Pressure (VIIP) syndrome, a spectrum of ophthalmic changes including posterior globe flattening, choroidal folds, distension of the optic nerve sheath, kinking of the optic nerve and potentially permanent degradation of visual function. In the cases of VIIP found to date, the initial onset of symptoms occurred after several weeks to several months of spaceflight, by which time the gross bodily fluid distribution is well established. We are developing a suite of numerical models to simulate the effects of fluid shift on the cardiovascular, central nervous and ocular systems. These models calculate the modified mean volumes, flow rates and pressures that are characteristic of the altered quasi-homeostatic state in microgravity, including intracranial and intraocular pressures. The results of the lumped models provide initial and boundary data to a 3D finite element biomechanics simulation of the globe, optic nerve head and retrobulbar subarachnoid space. The integrated set of models will be used to investigate the evolution of the biomechanical stress state in the ocular tissues due to long-term exposure to microgravity.
Document ID
20150002116
Acquisition Source
Glenn Research Center
Document Type
Presentation
Authors
Nelson, Emily S. (NASA Glenn Research Center Cleveland, OH United States)
Mulugeta, Lealem (Universities Space Research Association Houston, TX, United States)
Vera, J. (NASA Glenn Research Center Cleveland, OH United States)
Myers, J. G. (NASA Glenn Research Center Cleveland, OH United States)
Raykin, J. (Georgia Inst. of Tech. Atlanta, GA, United States)
Feola, A. J. (Georgia Inst. of Tech. Atlanta, GA, United States)
Gleason, R. (Georgia Inst. of Tech. Atlanta, GA, United States)
Samuels, B. (Alabama Univ. Birmingham, AL, United States)
Ethier, C. R. (Georgia Inst. of Tech. Atlanta, GA, United States)
Date Acquired
February 25, 2015
Publication Date
October 26, 2014
Subject Category
Aerospace Medicine
Report/Patent Number
GRC-E-DAA-TN18514
Meeting Information
Meeting: American Society for Gravitational and Space Research Annual Meeting
Location: Pasadena, CA
Country: United States
Start Date: October 22, 2014
End Date: October 26, 2014
Sponsors: American Society for Gravitational and Space Research
Funding Number(s)
WBS: WBS 516724.02.02.10
CONTRACT_GRANT: NNJ11HE31A
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
intraocular pressure
aerospace medicine
mathematical models
eye (anatomy)
intracranial pressure

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