Buying eyeglasses online on the basis of a sale or JPEG is as foolish as picking a pair of eyeglasses at random from the drugstore. Only buy eye glasses online or in the drug store if you know your diopter strength. One size does not fit all when it comes to eye glasses. You definitely don't want to risk getting the wrong pair. Invest in your eyes, see your eye doctor, and you can be assured that your glasses will fit you to an “I” (eye).