New research has found long duration weightlessness in space induces a blood shift leading to larger central volume expansion and lower blood pressure than expected.
A study was published in The Journal of Physiology this week finding a greater shift than previously thought.
Researchers measured the volume of blood ejected by the heart into the blood vessels and monitored the blood pressure of eight astronauts aged between 45-53 years during a 24 hour period with portable equipment.
Dr Peter Norsk, lead author of the study, said: ‘We know that some astronauts experience vision problems some months into spaceflight and this may in fact be caused by the augmented fluid and blood volume shift to the upper body.’
Previous research has shown astronauts to be vulnerable to eye diseases such as cataract, Optician clinical editor Bill Harvey said.
He added: ‘The shifts in perfusion pressure that this research highlights would result from long periods in spaceflight may have implications, not just in visual problems, but long term disease linked with microvascular perfusion compromise and also changes to the ratio of intraocular and systemic vascular pressures.’