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Parabolas? Glasses use lenses...which I guess have a sort of mathematical connection with parabolas.

Reading glasses use convex lenses, the shape of which causes light to converge to a focal point. They compensate for a lack of refractive power in the natural lens of the eye.

The light is actually "bent" as it passes through the lens. The bending occurs as a result of changes in the speed of light as it passes from air into the lens material and back into air again. A convex lens is like a radially arranged set of many prisms which refract (bend) light towards a single point. When the light enters the surface of the lens at an angle, different parts of the wavefront are slowed down at different times. This differential delay across the wavefront results in a changed direction of light as it travels through the lens. The light is bent again as it emerges into air on the other side.

A concave lens does the opposite. Concave lenses are used for nearsightedness.