Microgravity and Eyesight

Last time, we talked about the effects of mirogravity on brain function.  Today, let's look briefly on microgravity and eyesight.

This has gotten some media attention lately, thanks to a study done by the University of Texas School of Houston, which did MRIs of 27 astronauts and found several of them had abnormalities that resembled intracranial hypertension, which basically means the high pressure of the fluid in the skull.

According to the article on BBC News: 

(The) team examined astronauts who had spent more than 30 days of cumulative time in the weightless environment of space.  The group found evidence for expansion of the cerebral spinal fluid space surrounding the optic nerve of nine of the astronauts, a flattening of the rear of the eyeball in six, a bulging of the optic nerve in four, and changes in the pituitary gland and its connection to the brain in three individuals. The pituitary gland secretes and stores hormones that regulate a variety of important body functions.
Unfortunately, I could not find a copy of the study, so I cannot tell you if this means that 19 of 27 astronauts had symptoms, or if some had multiple symptoms.  The article also did not say how this might compare to a similar group of earth-bound people.  However, another study of 15 astronauts by the National Academy of Sciences said 7 of the 15 had experienced blurry vision as a result of intercranial pressure, and 35 percent of all space station astronauts have experienced blurry vision of some sort.

So, this is a potential problem, especially if the effects are cumulative or damaging if continued in long term.  It's one reason astronauts are usually limited to 6 month tours in space as most.  However, if we ever get moving to Mars, this may be more of an issue.

In October, the ISS got a new ultrasound machine, and have been using it to make studies of the eyes. 

The challenges for getting to Mars are more then technical, it seems.

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