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Accession Number N20130011122
Title Integrated Biomechanical Model for Microgravity-Induced Visual Impairment.
Publication Date Sep 2012
Media Count 16p
Personal Author E. S. Nelson J. G. Myers L. Mulugeta L. M. Best
Abstract When gravitational unloading occurs upon entry to space, astronauts experience a major shift in the distribution of their bodily fluids, with a net headward movement. Measurements have shown that intraocular pressure spikes, and there is a strong suspicion that intracranial pressure also rises. Some astronauts in both short- and long-duration spaceflight develop visual acuity changes, which may or may not reverse upon return to earth gravity. To date, of the 36 U.S. astronauts who have participated in long-duration space missions on the International Space Station, 15 crew members have developed minor to severe visual decrements and anatomical changes. These ophthalmic changes include hyperopic shift, optic nerve distension, optic disc edema, globe flattening, choroidal folds, and elevated cerebrospinal fluid pressure. In order to understand the physical mechanisms behind these phenomena, NASA is developing an integrated model that appropriately captures whole-body fluids transport through lumped-parameter models for the cerebrospinal and cardiovascular systems. This data feeds into a finite element model for the ocular globe and retrobulbar subarachnoid space through time-dependent boundary conditions. Although tissue models and finite element representations of the corneo-scleral shell, retina, choroid and optic nerve head have been integrated to study pathological conditions such as glaucoma, the retrobulbar subarachnoid space behind the eye has received much less attention. This presentation will describe the development and scientific foundation of our holistic model.
Keywords Aerospace medicine
Boundary conditions
Cardiovascular system
Computational fluid dynamics
Fluid shifts(Biology)
International space station
Intracranial pressure
Intraocular pressure
Long duration space flight
Mathematical models
Systems analysis
Time dependence
Visual acuity

Source Agency National Aeronautics and Space Administration
NTIS Subject Category 84 - Space Technology
57E - Clinical Medicine
Corporate Author National Aeronautics and Space Administration, Cleveland, OH. NASA John H. Glenn Research Center at Lewis Field.
Document Type Technical report
Title Note N/A
NTIS Issue Number 1320
Contract Number N/A

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