An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient. If an eye examination indicates that corrective lenses are appropriate, the prescriber generally provides the patient with an eyewear prescription at the conclusion of the exam.

Pupillary distance (PD), more correctly known as interpupillary distance (IPD) is the distance in millimeters between the centers of each pupil.