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Scientist Makes Strides in Preserving Vision for Astronauts

Brian Samuels, MD, PhD, Assistant Professor in the UAB Department of Ophthalmology, and his collaborators recently received a grant to study computational modeling as a method of determining why astronauts who are in space for extended amounts of time are experiencing eye pathologies. Many astronauts who come back from space experience poorer vision after flight, some even years later. The project is being led by C. Ross Ethier, PhD, Professor and Interim Chair of the Wallace H. Coulter Department of Biomedical Engineering at Georgia Institute of Technology and Emory University School of Medicine. Drs. Ethier and Samuels are collaborating with scientists at the NASA Glenn Research Center, and others, to help identify the cause of the pathologies and determine if there is a way to intervene and prevent these types of vision complications in the future.

“We know that if astronauts are in space for extended amounts of time they have a higher propensity for developing pathologies similar to increased intracranial pressure,” says Samuels. “We are trying to incorporate all of the existing clinical and research data into functional computational models of the eye itself, the central nervous system, and the cardiovascular system to determine how they are interacting. These computational models should answer some of the questions as to why this is happening to our astronauts.”

The length of time astronauts stayed in space changed in the mid-2000s when the International Space Station started being used. Space shuttle missions typically lasted two weeks, but now the ISS missions may last six months or longer. Astronauts were no longer going up to space and quickly coming back down to Earth. It was around this time the scientific community noticed that longer durations in space, in microgravity, caused a larger propensity for changes in the eye.

Many astronauts who experience these vision issues are encountering a hyperopic shift in their vision, meaning they gradually become farsighted. Astronauts can get folds in the retina, experience swelling of the optic disc, and also have distention of the optic nerve sheath behind the eye. Some astronauts who have returned from a mission are still experiencing vision issues five years later, so Dr. Samuels and his colleagues believe there may be some permanent remodeling changes in the eye after extended periods of time in space.

“Given that one of NASA’s primary goals is to send an astronaut to Mars, this will be the longest amount of time humans have spent in space thus far,” says Samuels. “If we are able to identify risk factors that might predispose someone to these types of health issues in space, the computational models could become a screening tool for future astronauts. We also want to find the direct cause behind these eye pathologies in an effort to develop tools to halt this process for astronauts in space. If an astronaut is six months from coming home and is already experiencing vision-related issues, we want to temporize any further damage that may occur.”

Samuels’ role in this project is to interpret clinical and research data that informs the computational modeling and relay back to the other investigators whether the output data obtained from the models is realistic. In other words, he is a clinical litmus test for the project. Samuels splits his time between the laboratory and the clinic. As a clinician-scientist, he can take information that is gathered from research studies, clinical studies, and computational modeling in the lab, and compare it to real-world scenarios in a clinic.

“Dr. Samuels is our point person for clinical calibration,” says Ethier. “We are trying to understand a complex pathophysiologic process, and the research inevitably requires that we make certain assumptions about how organs and tissues are responding to microgravity. Dr. Samuels helps ground us in clinical reality by relating effects in space to clinical conditions on earth, detailing pathophysiologic processes at the cellular level to clinical outcomes. He is an incredible resource for our team and the broader space physiology community.”