A refraction is that part of the eye exam that involves looking through many different lenses so that an optimal prescription can be determined for glasses or contact lenses.  The refraction tells the doctor what your best visual acuity is and what lens prescription is needed to achieve it.  It also provides the prescription that is the starting point for a contact lens fitting and evaluation. For routine eye exams with vision plans, the refraction is bundled together with the health evaluation part of the examination and billed together as one charge. When using medical insurance the refraction is considered a separate procedure and not part of the regular exam. It is almost never covered by medical insurance and is billed to the patient as an additional charge.