You just finished up your routine eye exam, but feel confused about your new glasses prescription. What are all those numbers and symbols? What does "axis" mean?
Key Takeaways
- "Axis" refers to a value in a glasses prescription. It is a value between 0 and 180 degrees.
- The axis value measures the orientation of the cylindrical power of the lenses that is needed to correct astigmatism.
- Cylinder power indicates the amount of lens power needed to correct nearsightedness or farsightedness.
See Related: Can You Get Prescription Sunglasses?
What Is an Eye Prescription?
Before we dive into what "axis" means, let's quickly review what an eye prescription is.
An eye prescription is a written order provided by an eye care professional that contains the necessary details for vision correction. It can include information such as the type of lenses, specific measurements, and other metrics, like the axis.
What Does "Axis" Mean in a Glasses Prescription?
In essence, the "axis" value in your eyeglass prescription refers to the orientation of the cylindrical power of the lenses.
But what does that really mean?
Axis tells you the position of astigmatism, but doesn't indicate the severity of astigmatism. It is there to orient the cylindrical power of the lenses that is needed to correct astigmatism.
Axis is always a value between 0 and 180 degrees. 90-axis refers to the vertical meridian, which is from top to bottom. 180-axis refers to the horizontal meridian, which is from side to side.
What About "Cylinder" and "Sphere"?
As we've established, the axis value is what orients the cylinder power for your corrective lenses. An axis value and cylinder power go hand-in-hand. If your glasses prescription includes a cylinder power, it must also include an axis value indicating the orientation of that cylinder power.
But what is a "cylinder power"? Denoted as "CYL", the cylinder power indicates the amount of lens power required for astigmatism correction, and represents the difference between the greatest and weakest powers of the eye. CYL power is usually separated by 90 degrees.
Since we're discussing axis and CYL values, we should also touch on SPH. Sphere power, or SPH, refers to astigmatism correction that is spherical in all meridians of the eye. SPH is measured in diopters, and usually corrects nearsightedness or farsightedness.
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What Is the Normal Eye Axis?
A normal eye axis just means that you either don't have astigmatism, or the astigmatism you have isn't severe or substantial enough to require corrective eyewear.
According to the American Academy of Ophthalmology, most people have an astigmatism of 0.5 to 0.75 diopters. You need corrective eyewear, such as eyeglasses or contact lenses, if you have an astigmatism of over 1.5.
The Bottom Line
Now, the next time you try reading your eye prescription, you'll understand what that curious value under the axis and cylinder column means.
If you're ready to update your prescription as well as your daily look, stop by our Seattle boutique and clinic. After your eye exam, you can take your pick of frames, from sleek, stylish cat-eye frames to bold, limited-edition Jacques Marie Mage eyeglasses.
Keep Reading: What Are Blue-Light Glasses, and What Do They Do?
People Also Ask
Is an Axis of 180 Good or Bad?
A 180-axis is not inherently "bad", since it doesn't tell you the severity of the astigmatism, only the orientation. If you have blurry or distorted vision, your optometrist can help pair you with corrective eyewear that helps you live comfortably and confidently.
Is a 150 Axis Bad?
A 150-axis can be considered normal and doesn't indicate a severe case of astigmatism. If you have issues with blurred vision or seeing clearly, visit your eye doctor for a diagnosis.
What Happens if the Axis on Glasses Is Wrong?
If your glasses have the wrong axis, it could cause things like blurry vision, wavy images, eye strain, or headaches. If you think your glasses have the wrong eyeglass prescription, stop by your eye doc for an updated eyeglass prescription.
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