Knowing how to read your eyeglass prescription is very important, so that you can order your eyeglasses online as quickly as possible. Here is a group of the most important abbreviations found in eyeglass prescriptions:

- (OS): It is an abbreviation of the Latin term oculus sinister, which means left eye.

- (OD): It is an abbreviation of the Latin term oculus dexter, which means right eye.

- (SPH): It is an abbreviation of the word Sphere, which refers to the pupil of the eye, and the ability of the lens to refract a ray of light. A positive sign (+) indicates farsightedness (difficulty focusing on close objects), while a negative sign (-) indicates myopia (difficulty focusing on distant objects).

- (CYL): It is an abbreviation for the word Cylinder, which is used to measure deviation (astigmatism). This box may be empty, or contain a positive (+) or negative (-) value. If it is empty, you do not suffer from astigmatism (deviation in vision).

- (Axis): It exists only if there is a value in the CYL box that tells us where the astigmatism (skewness) is in the eye.

- (ADD): It is an abbreviation for the word Addition, which is the additional correction required for reading. They can be used to make reading glasses, bifocal glasses,

After knowing all the abbreviations, symbols and letters in your prescription, this will help you order medical glasses online and discuss your prescription with your doctor more easily.