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Section 1

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Although a definitive cause for the symptoms outlined in the Existing Long-Duration Flight Occurrences section is unknown, it is thought that venous congestion in the brain and/or eye, brought about by cephalad-fluid shifts and which may have exacerbated choroidal volume changes, may be a unifying pathologic mechanism. Due to these findings, NASA has initiated an enhanced occupational monitoring program for all mission astronauts with special attention to signs and symptoms related to ICP.

Similar findings have been reported among Russian Cosmonauts who flew long-duration missions on MIR. The findings were published by Myasnikov and Stepanova in 2008.[1]

Section 2

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IOP Measurement

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Intraocular pressure (IOP) is determined by the production, circulation and drainage of ocular aqueous humor and is described by the equation:

 

Where:

F = aqueous fluid formation rate
C = aqueous outflow rate
PV = episcleral venous pressure

In general populations IOP ranges between and 20 mmHg with an average of 15.5 mmHg, aqueous flow averages 2.9 μL/min in young healthy adults and 2.2 μL/min in octogenarians, and episcleral venous pressure ranges from 7 to 14 mmHg with 9 to 10 mmHg being typical.

  1. ^ Mayasnikov, VI (2008). "Features of cerebral hemodynamics in cosmonauts before and after flight on the NIR Orbital Station". Orbital Station MIR. 2. Institute of Biomedical Problems: State Scientific Center of Russian Federation: 300–305. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)