The burgeoning era of space travel brings with it a host of new challenges, not least of which is the impact of altered gravity on the human body. One research team at Texas A&M University, led by Dr. Ana Diaz Artiles, has turned its attention to the potential effects on our eyes.
In the realm of space, the gravitational forces we’re used to on Earth are disrupted. This can cause a shift in bodily fluids, leading to changes in the cardiovascular system, which includes the blood vessels in and around our eyes. With the prospect of commercial space flights on the horizon, understanding these changes becomes even more critical. After all, the passengers on such flights may not be as physically prepared as astronauts, making them potentially more susceptible to these shifts in fluid balance.
Dr. Diaz Artiles explains, “In microgravity, the usual downward pull of gravity on our body fluids is absent. On Earth, when we’re upright, a large portion of our fluids is stored in our legs. In space, these fluids are redistributed into our upper body.”
This fluid displacement may be linked to a condition known as Spaceflight Associated Neuro-ocular Syndrome (SANS), which can result in changes to the eye’s shape and other ocular issues, including changes in ocular perfusion pressure (OPP). The exact cause of SANS is not yet entirely clear, but Diaz Artiles’ research aims to uncover the underlying mechanisms.
To combat the fluid shifts associated with SANS, Diaz Artiles and her team are exploring potential countermeasures. They’ve recently investigated the use of lower body negative pressure (LBNP) as a possible solution. LBNP could potentially counteract the microgravity effects by drawing fluid back into the lower body.
The team hypothesized that exposure to microgravity could cause a slight but sustained increase in OPP, which might play a role in the development of SANS. However, their recent study found that while LBNP effectively induced fluid shift back to the lower body, it did not effectively reduce OPP. If a definitive link between elevated OPP and SANS is established, LBNP might not be a successful countermeasure. The team emphasizes the need for further research to fully understand the relationship between OPP and SANS and assess the impact of LBNP on ocular responses.
Dr. Diaz Artiles explains, “This is just one part of a three-part study aimed at understanding the effects of fluid shift on the body and its potential link to SANS.” Previous experiments included the use of a tilt table to study the cardiovascular effects of fluid shifts under different gravity conditions.
Future research will investigate using a centrifuge to counteract the fluid shift. The team will collect data on cardiovascular responses to each countermeasure and compare their effects on OPP and other cardiovascular functions potentially affected by microgravity. Since these studies are carried out on Earth, the results may differ in real microgravity conditions, such as those experienced during space travel. Therefore, the team hopes to carry out future studies in true microgravity conditions, like parabolic flights.
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