Improving astronaut vision in long-haul spaceflights

Western Australian researchers have developed a breakthrough method to measure the brain fluid pressure in humans, which may reduce vision damage experienced by astronauts on long-haul space flights.

A cross-disciplinary team from the Lions Eye Institute and the International Space Centre (ISC) at The University of Western Australia has developed a clever technique to measure the pressure in brain fluid. This breakthrough study has been published by Nature in njp Microgravity.

Co-author Danail Obreschkow, Associate Professor at the International Centre for Radio Astronomy Research and ISC Director, said “These results may prove crucial to overcoming a type of blindness that frequently develops in astronauts on long-duration space flights.”

“The so-called Space Associated Neuro-ocular Syndrome (SANS) is one of the most serious risks for astronauts on long-duration flights,” elaborated Lions Eye Institute Managing Director and lead author Professor Bill Morgan. “NASA has identified SANS as a significant challenge on future crewed missions to Mars, and our study may help overcome this challenge.”

Pictured (L-R): Associate Professor Danail Obreschkow, Professor Bill Morgan

Our bodies evolved to counter the effects of gravity by pushing blood upwards into the head. In microgravity, this can lead to an increased average pressure in the cerebrospinal fluid, which adversely affects the retina. This deteriorates vision and other important functions. Until recently, cerebrospinal fluid pressure could only be detected through invasive methods such as a lumbar puncture or skull burr hole. Both techniques are painful, risky, and cannot be performed well in microgravity.

The researchers have now developed a space-safe and non-invasive method to measure cerebrospinal fluid pressure changes.

“All blood vessels experience tiny pulsations coming from the heartbeat. The strength of these pulsations in the tiny veins of the retina should, in principle, depend on the cerebrospinal fluid pressure,” said Professor Morgan.

In the study published in early April 2023, the researchers succeeded at measuring these tiny pulsation changes in human subjects. They used a special eye camera to measure the vein pulsations while the subjects were put into different positions on a tilt-table. This approached allowed the scientists to mimic the effects of variable gravity on the cerebrospinal fluid pressure.

Tilt table experiments on Earth are the only way of controllably altering the gravitational force upon the human body and allow researchers to alter the cerebrospinal fluid pressure in small definite increments. This allows us to test systems for measuring that incremental change. It also forces us to develop systems which can be used in any postural position necessitating portable, small handheld devices which are essential if such systems are to be used in space.

The new findings provide a basis for the use of a handheld portable non-invasive device in microgravity conditions that can monitor intracranial pressure.

Better monitoring and testing in space of SANS progression will improve astronaut health in long-haul flights.

Article originally posted by the International Space Centre.

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