Looking at your prescription for eyeglasses, you will see two headings labeled
- OD: Latin oculus dexter, meaning “right eye"
- OS: Latin oculus sinister, meaning “left eye”
If you have a heading labeled “OU,” which is Latin for oculus uterque, it pertains to “both eyes.”
Other headings that your eyeglass prescription may have include
- SPH (Sphere): The number indicates the diopter (abbreviated as “D") required to correct your vision. The farther it is from 0, the more vision correction you need. A minus sign (-) in front of the number indicates myopia (i.e. you are nearsightedness). A plus sign (+) in front of the number indicates hyperopia (i.e. you are farsightedness).
- CYL (Cylinder): This number indicates the diopter required to correct your astigmatism. It can have a minus (-) or plus (+) sign in front of it. The further it is from 0, the more astigmatism you have. If the cell is blank, it means your doctor has determined you don’t have or don’t need to correct your astigmatism.
- Axis: This number ranges from 0 to 180 and shows the orientation of your astigmatism corresponding to the curvature of your eye. Please note that Cylinder and Axis numbers must exist together. Sometimes, the Axis value is separated from the Cylinder value by an “x” (especially in handwritten prescriptions).