Your Prescription Explained

What it all means

Once your eye examination is complete and all the necessary tests have been done, the optometrist will give you a copy of your prescription. It can sometimes be difficult to understand the series of abbreviations and numbers used by optometrists when writing a prescription. Here are the explanations of some of the most commonly used terms.

Rx Prescription
R Right eye
L Left eye
SPH (Sphere) Is measured in Dioptres and shows how long or short sighted you are. If you are long sighted, the number in the sphere column will have a plus (+) before it. Conversely, if you are short sighted, the number will have a minus (-) before it. The higher the number the thicker the lenses will be. If the word ‘plano’ or ∞ is used this indicates zero power for this section.
CYL (Cylinder) Is a measure of the amount of Astigmatism that needs to be corrected. Astigmatism is when your eye is irregularly shaped, rather than round. If you see a DS in this box it stands for ‘Dioptre Sphere’and means the Customer has no astigmatism.
AXIS Gives us the direction of the astigmatism and is measured in degrees from 1 to 180. This is only stated if there is astigmatism in the prescription
ADD OR ADDITION This is the power added on to the distance prescription to enable people who need reading glasses to focus on close work. It is always written as a positive number, and is usually in the range +0.75 to +4.00.