If you've looked at a glasses prescription and noticed numbers labeled CYL and AXIS, you may have wondered what they mean.
These two measurements are commonly associated with astigmatism correction.
Quick Answer
Astigmatism is a refractive error caused by an irregular curvature of the eye's cornea or lens. CYL indicates the amount of astigmatism correction needed, while AXIS indicates the orientation of that correction.
What Is Astigmatism?
Astigmatism occurs when the shape of the eye causes light to focus improperly on the retina.
Instead of having a more uniform curvature, the cornea or lens may have different curvatures in different directions.
This can contribute to:
- Blurry vision
- Distorted vision
- Difficulty seeing clearly at certain distances
- Eye discomfort
The National Eye Institute lists astigmatism as one of the common types of refractive error.
What Does CYL Mean on a Prescription?
CYL stands for cylinder.
It represents the amount of lens power used to correct astigmatism.
For example:
CYL -1.00
means the prescription includes a cylinder correction of -1.00 diopters.
The actual prescription format can vary, including whether the prescription is written in plus-cylinder or minus-cylinder form.
What Does AXIS Mean?
AXIS describes the orientation of the cylinder correction.
It is expressed in degrees from:
1° to 180°
For example:
CYL -1.00
AXIS 90
The CYL tells you the amount of astigmatism correction.
The AXIS tells the optical laboratory how that correction should be oriented.
CYL vs. AXIS
| Prescription Term | Meaning |
|---|---|
| SPH | Spherical power |
| CYL | Cylinder power for astigmatism |
| AXIS | Orientation of cylinder correction |
| ADD | Additional near power |
| PD | Pupillary distance |
Can You Have Astigmatism Without CYL?
If your prescription does not contain a cylinder value, it generally means no cylinder correction has been prescribed.
Can Astigmatism Be Corrected With Glasses?
Yes.
Prescription eyeglasses are one of the standard ways to correct refractive errors, including astigmatism.
The lenses are manufactured according to the prescription's spherical, cylinder, and axis values.
Can Astigmatism Cause Blurry Vision?
Yes.
Blurred or distorted vision is one of the common symptoms associated with refractive errors.
If your vision changes unexpectedly, an eye examination can determine whether your prescription needs to be updated.
Can You Buy Glasses Online With Astigmatism?
Yes, provided the retailer supports your prescription parameters.
When ordering prescription glasses online, you may need to enter:
- SPH
- CYL
- AXIS
- PD
- ADD, if applicable
Always enter your prescription exactly as written.
Why Is AXIS Important?
AXIS isn't an amount of lens power.
Instead, it tells the lens manufacturer the direction in which the cylinder correction needs to be positioned.
An incorrect axis can therefore result in a lens that doesn't match the prescribed correction.
What Happens If You Enter CYL or AXIS Incorrectly?
Prescription accuracy matters.
If you aren't sure how to interpret your prescription, don't guess.
Contact your eye-care provider or the retailer's prescription support team before ordering.
Frequently Asked Questions
Is CYL the same as astigmatism?
CYL is the cylinder power used to correct astigmatism on a prescription.
What does AXIS 90 mean?
It indicates the orientation of the cylinder correction at 90 degrees.
Is higher CYL worse?
A larger cylinder value means a greater amount of astigmatic correction is prescribed, but the number itself should not be interpreted as a simple measure of eye health.
Can glasses fix astigmatism?
Prescription glasses can correct the refractive effects of astigmatism and improve clarity while worn.
Do I need CYL and AXIS for astigmatism glasses?
If your prescription includes cylinder correction, the corresponding CYL and AXIS information is generally needed to manufacture the lenses accurately.
Final Takeaway
The easiest way to remember these prescription terms is:
CYL = How much astigmatism correction
AXIS = Which direction the correction is positioned
If your prescription includes CYL and AXIS, enter both values exactly as provided.
Trusted External Sources
- National Eye Institute — Refractive Errors
- National Eye Institute — Eyeglasses for Refractive Errors
Suggested Internal Links
- How to Read Your Glasses Prescription
- What Is Pupillary Distance?
- Prescription Glasses
- How to Order Prescription Glasses