Can you be an astronaut if you're nearsighted?

NASA's vision requirement isn't about flawless eyes, but about outcome: distant visual acuity correctable to 20/20 in each eye, measured separately. Glasses, contact lenses, and corrective lenses worn inside the helmet are all compatible with the job, and a good share of the astronaut corps uses them. Alongside vision, candidates are also assessed on blood pressure, height — constrained by the dimensions of seats and suits — and a full medical exam, with standards roughly comparable to those applied to a military pilot.

For years, having had vision correction surgery disqualified a candidate outright, out of concern that the cornea might behave unpredictably under pressure changes. Today the surgery is accepted: anyone who has undergone PRK or LASIK can apply as long as at least one year has passed since the procedure, the refraction is stable, and there are no remaining complications. It's the same path air forces had already cleared for their pilots, and ESA applied an equivalent standard in its 2021 selection round, where corrected myopia likewise excluded no one.

The limit isn't myopia itself, but whatever can't be corrected: acuity that doesn't reach 20/20 even with correction, retinal disease, glaucoma, or conditions that worsen in flight. On top of that, there's a phenomenon that affects people once they're already up there: microgravity shifts fluids toward the head and flattens the back of the eyeball in many long-duration crew members, who return with altered near vision. That's why vision is monitored before, during, and after every flight — and wearing glasses is a minor detail next to that risk.