If your eye doctor told you that you have astigmatism, you're in good company. It's one of the most common vision conditions, and glasses correct it easily.
What astigmatism is
In a perfectly round eye, light focuses to a single point. With astigmatism, the cornea (the clear front of the eye) or the lens inside is shaped more like a football than a basketball. Light focuses differently in different directions, which can make things look blurry or stretched at any distance and can cause eye strain or headaches.
Where it shows up on your prescription
Astigmatism correction appears in two boxes:
- CYL (cylinder): the amount of astigmatism correction, in diopters, like -0.75.
- Axis: the direction of the correction, a number from 1 to 180.
CYL and Axis always go together. If CYL is blank, 0.00, "DS" or "SPH," there's no astigmatism correction for that eye, and Axis will be blank too.
Minus or plus cylinder?
Some doctors write CYL as a minus number and some as a plus number. They're two ways of writing the same correction, and the Axis changes to match. Copy your prescription exactly as written. Don't convert it yourself.
What the axis number means
Axis is measured in degrees, like a protractor. 90 is vertical and 180 is horizontal. The number doesn't mean better or worse; it just tells the lab which way to rotate the correction in the lens. A small copying error in the axis can make glasses feel off, so double-check it.
Can you buy glasses online with astigmatism?
Yes. Single vision lenses correct astigmatism using the CYL and Axis values, and you can order them online like any other prescription. At Fast Eyeglasses, enter your CYL and Axis at checkout. The Axis box turns on as soon as you choose a CYL. You can also upload a photo of your prescription.
Tips
- Copy CYL and Axis for the right eye (OD) and left eye (OS) separately. They're often different.
- A CYL of 4.00 or more is uncommon. Our checkout flags it so you can double-check.
- If your astigmatism is new or has changed a lot, give yourself a few days to adjust to new glasses.
Read the full guide to reading your prescription, or shop frames.
