Cahill

Distance lenses that correct blurry vision for far away objects, while things up close remain clear.

Multifocal lenses that improve your vision for objects both near and far away.

Reader and intermediate lenses for those who have trouble focusing while reading.

Lenses that complement your personal style.

It’s just what it sounds like — the distance in millimeters (mm) between your pupils. An average PD measurement in 63mm, but it varies by person. If your PD number isn’t on your prescription, you can measure it yourself by:

Lens strength needed to correct your vision. Positive (+) means farsighted, negative (-) means nearsighted.

The degree of astigmatism in your eyes, as well as an axis number that indicates the orientation of the astigmatism.

ADD stands for the additional correction that you need for reading. It’s used for multifocal lenses and readers.

Prism is power, measured in diopters, used to correct vision displacement, like double vision or an eye turn. Most eyeglass prescriptions do not have prism correction. A prescription with prism will have two values per eye: a Prism (power) and Base (direction).

Vertical prism correction is for vertical eye misalignments & prescribed upwards in one eye and downwards in the other.

Horizontal prism correction is for lateral eye misalignments & prescribed in the same direction for both eyes.