How to read your prescription?

SPH: Sphere, the power of your prescription. If the numbers in this column have a minus (-), this means you are nearsighted (myopia). If it’s a plus (+), you are farsighted (hyperopia). The value is measured in diopters.

CYL: Cylinder. The amount of lens power for astigmatism. A minus before the number in this column is for nearsightedness, a plus for farsightedness. If you have no or very slight astigmatism, nothing will appear in this column. The value is measured in diopters.

Axis.: Or shows up as Ax. Like CYL, it applies to astigmatism, so if there’s not CYL, there will be no number under AX. It’s measured in degrees/angles, and the number will be between 1 and 180.

Add: Only used for multifocals. Added magnifying power to correct presbyopia, which means adding power to the distance Rx in order to create reading-only Rx. Usually, it will range between +0.75 to +3.00. Some prescriptions from a doctor will mention PAL, which means you’ll need a different addition to progressive adjusted lens compared to bifocal multifocal lenses.

Prism: Prismatic power added to compensate for eye alignment problems. A small percentage of prescription glasses include a prism.

PD (pupillary distance) is also an important part of the prescription, referring to the distance between the center of your pupils.

An eyeglasses prescription is not a prescription for contact lenses. Contacts prescriptions are obtained in a contact-lens specific fitting, and they include additional information (base curve, lens diameter and more) and the prescription power is often different because glasses have a small distance from the eye, while contacts sit right on the eye.