STS-41 crewmembers conduct Detailed Supplementary Objective (DSO) 472, Intraocular<unk>  on the middeck of Discovery, Orbiter Vehicle (OV) 103. Mission Specialist (MS) William M. Shepherd rests his head on the stowed treadmill while Pilot Robert D. Cabana, holding Shepherd's eye open, prepares to measure Shepherd's intraocular<unk>  using a tonometer (in his right hand). Spaceflight-induced<unk><unk>  is hypothesized to be a result of increased<unk><unk> . The study of<unk>  changes and<unk><unk>  (ICP) in astronauts on long-duration flights is a relatively recent topic of interest to Space Medicine professionals. Although reported signs and symptoms have not appeared to be severe enough to cause blindness in the near term, long term consequences of chronically elevated<unk><unk>  is unknown. NASA has reported that fifteen long-duration male astronauts (45–55 years of age) have experienced confirmed<unk>  and anatomical changes during or after long-duration flights. Optic disc edema, globe flattening, choroidal folds, hyperopic shifts and an increased<unk><unk>  have been documented in these astronauts. Some individuals experienced transient changes post-flight while others have reported persistent changes with varying degrees of severity. Although the exact cause is not known, it is suspected that microgravity-induced cephalad fluid shift and comparable physiological changes play a significant role in these changes. Other contributing factors may include pockets of increased CO2 and an increase in sodium intake. It seems unlikely that resistive or aerobic exercise are contributing factors, but they may be potential countermeasures to reduce intraocular<unk>  (IOP) or<unk><unk>  (ICP) in-flight.
Visual impairment due to intracranial pressure
Acute visual loss
Eye injuries during general anaesthesia
Recurrent painful ophthalmoplegic neuropathy
Infectious intracranial aneurysm
Brain ischemia
Blast-related ocular trauma
Intraoperative floppy iris syndrome