How to read a prescription

Knowing how to read a prescription for eyeglasses is essential! You may know whether you are nearsighted, farsighted, or astigmatic, but determining that from your prescription is another matter entirely. That's why we've put together this short guide to help you understand how to read your eyeglass prescription so you can order your new glasses as quickly as possible.

If there is a change in vision after an eye exam, you should consult your optometrist or ophthalmologist to have a new prescription written.

Most online retailers will ask you to read your prescription and fill out an order form, but the process can be complicated if you do not know how to read a prescription.

How to read prescriptions

If you have a previous prescription for an eye exam, you can use it here. The numbers may seem complicated at first, but don't worry, we will explain them in more detail below.

R (OD) & L (OS)

OD = right eye OS = left eye


Spherical power indicates the degree of myopia or hyperopia, with positive values indicating hyperopia and negative values indicating myopia.


The added lens power is for presbyopia and is the lens power required for near-sighted people to adapt to near vision.


Number of corrections required for astigmatism


Axial is the position, in degrees, corresponding to the degree of astigmatism on the lens of the eyeglasses, specifically the angle of rotation of the eye.


The interpupillary distance is the distance between the centers of the pupils of the eyes and is measured during eye examinations.


What is diopter measurement?

Diopter is a scale used to measure the strength of spectacle lenses. The numbers under the prescription "OD" and "OS" measurements are measured in diopters.

What are strong eyes?

The higher the prescription number, the stronger the prescription. A minus sign in front of the number means nearsightedness, and a plus sign or no sign in front of the number means farsightedness. Generally, numbers above 5 are considered to be on the strong side.

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