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.
|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.|