How to Read an Eyeglass Prescription
Spherical error, or the overall lens power, is the basic part of your prescription. You’ll notice (+) and (-) signs on your prescription. When there’s a (+), it means you have trouble seeing near, and when there’s a (-), it means you have trouble seeing far away.
CYL (Cylinder) & Axis
A cylinder value indicates astigmatisms, or perpetually blurry vision. The axis — measured between 1° and 180°— tells us the orientation of the astigmatism.
The ADD number is sometimes written NV for near vision, and is used for multifocal lenses and readers.