Spaceflight associated neuro-ocular syndrome

His eyes had physically changed shape.

This condition is called vision impairment and intracranial pressure, or VIIP.

It happens because fluids rush upward when gravity disappears.

The increased intracranial pressure pushes on the optic nerve and flattens the eye.

Then there is the vision problem.

NASA identified a condition now called Space Flight Associated Neuro-Ocular Syndrome, or SANS, after discovering that a significant percentage of astronauts returning from long-duration missions had measurable changes to their eyes.

Globe flattening, optic disc swelling, shifts in visual acuity.

The leading hypothesis is that the headward fluid shift in microgravity increases intracranial pressure pressing on the optic nerve and altering the shape of the eyeball.