what does cylinder mean for glasses
On an eyeglass prescription, “cylinder” (often written as CYL) tells you how much astigmatism your eye has and how strong the correction needs to be for it.
What “cylinder” actually means
- The cylinder value is the extra lens power built into your glasses to correct an astigmatism , which is an irregular shape of the cornea or lens that makes light focus unevenly.
- If your prescription has no cylinder number , it usually means you don’t have significant astigmatism.
How it appears on your prescription
- You’ll see CYL (or “Cylinder”) next to a number like –1.00, +1.50, etc., measured in diopters.
- A minus cylinder (e.g., –0.75) typically corrects nearsighted astigmatism; a plus cylinder (e.g., +1.25) corrects farsighted astigmatism, depending on the notation your optometrist uses.
Cylinder plus axis
- Cylinder always comes paired with an axis number (from 0 to 180 degrees), which shows the direction the cylinder power is placed in the lens to match the odd curve of your eye.
- Together, CYL + axis let the lab make lenses that smooth out your astigmatism so your vision looks clearer and less blurry or distorted.
| Term | Role in glasses prescription |
|---|---|
| Sphere (SPH) | Basic power for nearsightedness or farsightedness (spherical correction). | [4][9]
| Cylinder (CYL) | Extra power needed to correct astigmatism; higher number = stronger astigmatism. | [7][3][9]
| Axis | Angle (0–180°) showing where the cylinder power is oriented in the lens. | [5][3]