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Of: TT
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Photo: John Raoux / AP / TT
Before humans are sent to Mars, scientists must take a closer look at how vision can be affected by long stays in weightlessness.
Astronauts are visually impaired when in space. And time in weightlessness is crucial, compounding obstacles before the first trip to Mars.
– This is something you want to understand better, says Professor Anders Eklund, who led the study.
After examining the astronauts, researchers at Umeå University and Dartmouth College in the US believe they have found a connection between elevated brain pressure and an extension of the optic nerve. The new knowledge could be another hurdle in plans to send humans to Mars.
Anders Eklund, professor of medical technology at Umeå University, has led the project together with Jay C Buckley, an astronaut and professor of medicine at Dartmouth College.
Measurements have been made on astronauts before and after they have been in space. They were done with an MRI camera that looked at the optic nerve and brain structures.
– Analysis shows that the optic nerve stretches when you are in space and that this in turn affects the eye and vision, says Anders Eklund.
Vision is affected, especially by affecting myopia, something that is solved in space travel simply by sending with reading glasses. However, visual impairment can last for a long time even after returning to earth. The changes are so great that there are concerns that prolonged space travel could cause vision loss, according to the researchers. The distance to Mars is about 200 times greater than to the Moon.
More clearly for a long time
In the project, the scientists studied two groups of astronauts heading to the International Space Station ISS. Part a group that was in space for six months, part one that was active for two weeks.
– You see the effect in both groups, but it is clearer in those who have been awake for a long time. So it’s a progression, but it’s hard to say exactly what it looks like after this study. Because you are concerned that an extension of the optic nerve could damage the eye, this is something you need to understand better. Especially if you are planning trips to Mars and will be weightless for a long time, says Anders Eklund.
The results indicate that the elongation of the optic nerve is due to an imbalance between intracranial pressure – brain pressure – and pressure in the eye. Therefore, the next step is to measure brain pressure before and after space travel.
– We have equipment for that in Umeå. In addition, we have been in Houston and installed measurement systems there together with researchers from the US We are ready to take such measurements today, says Anders Eklund.
More measures are needed
But to really understand physiology, you need to take measurements on astronauts while they are on a space station, says Anders Eklund.
– I think it will be necessary to take measurements in space to really understand what happens in weightlessness. Some measurements have been made on submersible aircraft, but it is difficult since they are weightless for such a short time, says Anders Eklund.
The knowledge from the study is now used in brain and eye disease research here on earth.
– Above all, we look at diseases of the eye, where elevated brain pressure can be a cause.
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