Did you know that NASA has a fully equipped eye care clinic at the International Space Station? It’s become a necessity.
We’ve learned that while in space, in addition to bone and muscle density changes, astronauts’ eyes go through visual and physical changes as well.
Astronauts can experience SANS during space travel, Spaceflight Associated Neuro-ocular Syndrome.
While in space, the eye globe experience flattening. This causes a hyperopic shift, making the astronauts become more farsighted.
During their time in micro gravity, an astronaut who’s vision is normally 20/20 on Earth may become up to 20/100 or worse in space. Astronauts are given a pair of “space glasses” before leaving on each trip.
Among other changes, there’s optic nerve swelling in one or both eyes, and nerve fiber layer infarcts. When the nerve swells it can cause visual disturbances, headaches, and nausea. Sometimes nerve swelling can be caused by a build-up of pressure in the brain. Nerve fiber infarcts appear as fluffy white patches on the retina, the back part of the eye. Normally these are caused by damage to the nerve fibers in the eyes. This is concerning as it has the potential of vision loss over time.
Though it is extremely expensive to send equipment into space (it costs close to $10K to send a can of coke), they made it a priority to equip the ISS with a state-of-the-art eye clinic.
The astronauts do eye exams on a continual regular basis. They use eye charts (to check vision), tonopen (to measure eye pressure), OCT (optical coherence tomography to image the back of the eye), A-Scans (to measure the length of the eye) and dopplers (ultrasound of the retina) as often as possible. They take pictures of the inside of their eyes to track the changes.
The good news is most of the blurred vision seem to be temporary and is resolve within around 6 months once back on Earth.
The not so good news is that so far, the structural changes in the eye seem to be more persistent. We are continuing to study and learn more about the impact of space travel on the eyes.
To learn more, tune into this very informative podcast by Fayiz Mahgoub and Nitya Murthy, a 4th year optometry student doing a study in this area.
Photo courtesy of NASAEyes In Space