You just had your eyes examined by an optometrist and at the end he/she gives you a record of your spectacle prescription(s). The doctor probably mentioned that you are either nearsighted or farsighted. Or perhaps even told you that you have a little bit of astigmatism or presbyopia. Have you ever wondered what all the numbers and letters mean on your prescription?
OD: Oculus Dexter (latin) or Right eye
OS: Oculus Sinister (latin) or Left eye
Sphere: It’s the amount of lens power that is measured in diopters. If you have a (-), it means you are nearsighted or myopic. If you have a (+), it means you are farsighted or hyperopic
Cylinder: this tells you the amount of astigmatism you have. This means your eyeball is oval shape like an egg.
Axis: This describes the angle of the astigmatism. It can be measured from 0 degrees to 180 degrees. If you have astigmatism, your eyeball is not round and has an oval shape. So all astigmatism will require the axis in the prescription.
Add: This is the magnifying power you need to correct presbyopia (a condition where your eyes are not able to focus up close) Usually this is prescribed at the age of 40 and over.
Prism: This is used for patients that are suffering from double vision. The prism is also measured in diopters and also needs to have a specified direction of the base (in, out, up or down).
Note: An eyeglass prescription is not the same as a contact lens prescription. Contact lens prescriptions need to include base curve, lens diameter and the specific manufacturer and brand name of lenses. The power of your contacts may also be different than your glasses (sphere, cylinder, axis)
If you have any questions, feel free to contact us at Avenue Eyecare.
Vancouver Kerrisdale Optometrist
Contact Avenue Eyecare to book your appointment today.