The prescription of contact lenses and eyeglasses have a slight difference. It’s mainly because eyeglasses are further from the eye while contact lenses lay directly on the eye. Make sure that you always have a copy of your contact lens prescription, and if something is unclear about it, do not hesitate to ask your eye care specialist.
Keep reading to learn more about your contact lens prescription.
Base curve (BC) pertains to the back curvature of your contact lens and is measured in millimeters. Your prescription will match your cornea’s curvature for the right fit and health of your eye. A person with a steeper curve in their cornea will have a lower number.
Ocular sinister (OS) refers to the left eye, while ocular dexter (OD) refers to the right eye. The prescription is the same measurement in both eyes if there is OU (ocular uterque) in your prescription.
DIA means diameter. It is the distance from one edge of your contacts to the other. It is measured in millimeters as well, and it determines where the edges of the lens will rest on the eye. With a correct measurement, the likelihood of irritation from contact lens wears decreases. Make sure to let your eye doctor know if you feel uncomfortable wearing your lenses.
The color is only included in your prescription if your contacts are colored.
Add power is used with bifocal lenses, and its measured in diopters.
Cylinder or CYL is measured in diopters. It displays the level of your astigmatism. You’ll find a negative sign if you are nearsighted and a plus sign if you’re farsighted.
Axis is measured in degrees and indicates the orientation of the cylinder lens.
For your contact lenses and eyeglasses, turn to your local low vision specialist, Joel H McGahen OD. Call us at (717) 264-4012 or fill out our contact form to make an appointment. We assist patients in Shippensburg and Greencastle, PA.