This number indicates the degree of correction needed for nearsightedness or farsightedness.

Negative (-): Corrects nearsightedness (myopia). Positive (+): Corrects farsightedness (hyperopia).

If present, this value addresses astigmatism, a condition caused by an irregularly shaped cornea. The number can be negative or positive and is often accompanied by the Axis.

The Axis (0 to 180 degrees) specifies the orientation of the astigmatism correction. A higher number does not mean more severe astigmatism; it’s simply a directional reference.

Found in prescriptions for bifocals or progressive lenses, ADD indicates additional magnifying power needed for reading or close-up tasks.

1. Select the Right Lenses Based on Your Prescription:

For single vision, you’ll primarily focus on SPH, CYL, and Axis. For multifocal needs, refer to the ADD value. For astigmatism, make sure the retailer offers lenses catering to CYL and Axis corrections.

2. Understand PD (Pupillary Distance):

Your PD measures the distance (in millimeters) between the centers of your pupils. It ensures that the optical center of the lenses aligns with your eyes for clear vision. If your PD is not included in the prescription, you may need to measure it yourself (try our SmartFit technology) or request it from your doctor.