Originally Posted by nemesis
Prescription lenses will not work as they need to be no less than an inch away from your eye for them to function properly.
They need to be that distance to function as corrective vision lenses, i.e in spectacles, but converging lenses (to correct long sight) also function as magnifiers at longer distances. Diverging lenses (to correct short sight) would be as useful as a chocolate teapot in this scenario, just making things look smaller.
This is how you can tell if spectacle wearers have long or short sight (as long as they have a strongish prescription). If their eyes look bigger in the specs they are long-sighted, if they look smaller they are short-sighted.