What Does My Glasses Prescription Mean?Monday, April 4th, 2016, 2:21 pm
What Does My Glasses Prescription Mean?
The Academy of Ophthalmology states that over 150 million Americans use corrective eyewear to correct their refractive errors. When you visit your eye doctor to get a new eyeglasses prescription, you are given a prescription that looks something like this:
So, you ask, what do all of these words and numbers mean? Here is a primer to help you decode your eyeglasses prescription.
Right and Left Eyes
There are 2 rows on an eyeglasses prescription. Your eye doctor determines the prescription for each eye individually. Some people (like our pretend patient above) have the same prescription in both eyes, but many people have a different prescription in each eye.
Sphere: This dimension of an eyeglass prescription is measured in diopters and tells you about the amount of lens power needed to correct your nearsightedness or farsightedness. If the number in the spherical column on your prescription is negative (there is a minus (-) sign) then you are nearsighted. If the number in the spherical column on your prescription is positive (there is a plus (+) sign) then you are farsighted.
Cylinder: This dimension of an eyeglass prescription tell you how much lens power is needed to correct your astigmatism. If there is no number in the cylinder column, you either do not have astigmatism or your astigmatism is insignificant enough that you do not need correction in your glasses for it. Astigmatism is an imperfection of the cornea and may occur in conjunction with nearsightedness or farsightedness. About 1 in 3 Americans have astigmatism.
Axis: This dimension helps define the degree of astigmatism in a glasses prescription. The axis is always a number between 1 and 180.
Add: The add is the additional magnification power used to correct reading distance vision for patients who have presbyopia. Add powers always have a plus (+) sign and is measured in diopters.