Prescription usually will be provided from your eye doctor at the end of the eye exam. You need to fill in the information from the prescription whenever you are going to order your eyewear online. Please also remind your eye doctor to measure your PD. Your PD number is required in the ordering process.
Here is the definition of each term:
Sph is the amount of Myopia (nearsightedness) or Hyperopia (farsightedness) in your eyes. The sign in front of the number indicates near (-) or far (+) sightedness.
Cyl (Cylinder) is the amount of astigmatism in your eyes.
Axis refers to the angle of the correction for the astigmatism in your eyes. If you have astigmatism, then there must be an axis.
Add is the correction for reading/near vision in your eyes.
The Pupillary Distance (PD) is the distance from one eye to the next. Usually the nearly pupil is 3-4 mm less than far pupil. The purpose of measuring pupil distance is to insure that each lens is aligned with your unique set of eyes. This will also increase the comfort of your new set of eyeglasses. Inaccurate PD measurement may lead to user experiencing vision fatigue, dizziness and nausea. Please be advised that most optometrists do not provide this important information in the prescriptions.