Spaceflight not an eye‐popping experience for astronauts

Modelling large scale artery haemodynamics from the heart to the eye in response to simulated microgravity

“…From a database of 14 astronauts, they found an average increase in velocity of 36.1% combined across the left and right eyes from pre-flight values to inflight values, similar to the increases in CRA peak velocity calculated in our study (30-31%). The slightly lower relative changes in velocities in our study may be explained by the assumption of rigid geometry, as Sirek et al also observed an 11% increase in optic nerve sheath diameter, which may compress the CRA, decreasing its diameter resulting in increases in velocity 55 ; this was not accounted for in our model. Interestingly, ground-based experiments have found even greater increases in retinal blood flow, with Laurie et al 56 measuring CRA velocity increases of 43–48% in HDT and HDT with hypercapnia compared to seated measures.…”

Homo sapiens—A Species Not Designed for Space Flight: Health Risks in Low Earth Orbit and Beyond, Including Potential Risks When Traveling beyond the Geomagnetic Field of Earth

“…As the vascular adaptations to microgravity involve the redistribution of fluids, there can be increased cerebral fluid [ 53 , 59 ] and increased fluid pressures in organs such as the eyes of both astronauts [ 60 , 61 , 62 ] and preclinical models, such as mice [ 63 ]. This can lead to visual disturbances [ 64 ], possibly related to effects on the eye itself [ 65 ], or the optic nerve [ 66 ].…”