Space missions may damage eyes
Key points
- Astronauts experience bone and muscle loss in the weightlessness of space, and now the first study of returning space travelers' eyes suggests that prolonged amounts of time in orbit can take a significant toll on vision, although the long-term effects aren't clear.
- Retrospective, observational examination of ophthalmic findings in 7 astronauts and analysis of postflight questionnaires regarding in-flight vision changes in approximately 300 additional astronauts.
- Seven astronauts with ophthalmic anomalies upon return from long-duration space missions to the International Space Station and 300 additional astronauts who completed postflight questionnaires regarding in-flight vision changes.
- Before and after long-duration space flight, all 7 subjects underwent complete eye examinations, including cycloplegic and/or manifest refraction and fundus photography.
Astronauts experience bone and muscle loss in the weightlessness of space, and now the first study of returning space travelers' eyes suggests that prolonged amounts of time in orbit can take a significant toll on vision, although the long-term effects aren't clear.
The new study, of more than 300 astronauts in the U.S. space program, found that almost 50 percent of those who served on long missions - six months or more - reported experiencing new problems with their ability to see objects near to them while in space and for some time after returning to Earth. Roughly 23 percent of astronauts who spent shorter periods in orbit reported problems with their near vision during their missions and after getting home.
The NASA-funded researchers also did physical exams on seven male astronauts who complained of vision problems after returning from six-month tours in space. They found several signs of eye stress in all of them, including a buildup of fluid around the optic nerve, the development of folds in the bed of vessels that supply blood to the retina, flattening of the eyeball and more.
"People have been flying in space for 50 years and nobody has gone blind yet," said Dr. Tom Mader, an ophthalmologist at the Alaska Native Medical Center, in Anchorage, who led the study. "But it's still something to be concerned about," he told Reuters Health.
Mader said the effects may be due to increased pressure of the fluid surrounding the brain - the result of less gravity than on Earth - that fails to drain well back into the body. But the precise mechanism is unclear.
Purpose To describe the history, clinical findings, and possible etiologies of ophthalmic findings discovered in 7 astronauts after long-duration space flight, and document vision changes in approximately 300 additional astronauts.
Design
Retrospective, observational examination of ophthalmic findings in 7 astronauts and analysis of postflight questionnaires regarding in-flight vision changes in approximately 300 additional astronauts.
Participants
Seven astronauts with ophthalmic anomalies upon return from long-duration space missions to the International Space Station and 300 additional astronauts who completed postflight questionnaires regarding in-flight vision changes.
Methods
Before and after long-duration space flight, all 7 subjects underwent complete eye examinations, including cycloplegic and/or manifest refraction and fundus photography. Six underwent postmission optical coherence tomography (OCT) and magnetic resonance imaging (MRI); 4 had lumbar punctures (LP). Approximately 300 astronauts were queried regarding visual changes during space missions.
Main Outcome Measures
Written and revised by
David Cohen, M.D.
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