The astronauts on the Discovery right now are actually quite old! The average age on the shuttle is 48 and many suffer from presbyopia, meaning they need some sort of glasses to help 'em out. Enter Superfocus glasses.
In addition to looking like the glasses Harry Potter wears, Superfocus glasses have the ability to change their focus - fixing nearsightedness or farsightedness - by adjusting a slider.
They are built using a set of front lenses to hold the wearer's distance prescription, while inner lenses contain a clear fluid. Moving a slider on the glasses' bridge adjusts this fluid, allowing people to focus on objects that are nearby or in the middle distance.