their eyeglasses prescription. Accordingly, each optical shop must be prepared to determine the prescription from the eyeglasses themselves. A machine, called a "lensometer", is customarily used in optical shops
Prescription eyeglass lenses are curved in such a way that light is correctly focused onto the retina of a patient's eye, improving vision. Such lenses are formed from glass or plastic lens “blanks” having certain desired properties to provide the correct prescription for the patient. The blan...