Eyeglass prescription specifies the definite value of the corrective lenses required by the patient, to correct his / her near and / or distant vision. DV or Distance Vision defines the parameters needed for the improvement of the far vision. DV can be defined as the vision for objects placed more than 20 feet from you. Over the times, numerous eye experts have come up, who offer computerized testing of eye, giving exact power of each eye, based on which lenses are made for the patient.