This is part of our annual comprehensive eye exam. It is the procedure in which we determine the best corrected visual acuity of each eye for purposes of medical evaluation or for prescribing corrective eyeglasses, contact lenses, or corrective surgery. A change in refraction can be the first sign of eye diseases such as cataracts. Most medical insurance plans, including Medicare, do NOT cover refractions. Medicare allows that we charge separately for that portion of the examination, since it is not a covered service.