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What does axis mean on my prescription?Medically reviewed by Alastair Lockwood, Eye Health Advisor, Ophthalmologist and Eye Surgeon at Feel Good Contacts.
The axis number on your contact lenses prescription or glasses prescription helps them know how to place the cylindrical power correctly in your lenses. Think of it as a direction indicator ranging from 1 to 180 degrees.
What is a normal eye axis?
It's important to note that there isn't a fixed ‘normal’ axis. This is because the eyeball is not perfectly round, and astigmatism (which is an irregular shape of the eye) can cause variations. To illustrate, if someone has a spherical (round-shaped) eye, there won't be a specific axis mentioned in their prescription because there's no irregularity in the shape requiring adjustment along a particular axis.
Is astigmatism 180 axis bad?
No, an astigmatism axis of 180 degrees just indicates the direction the astigmatism is at and has nothing to do with a person’s degree of nearsightedness or farsightedness.
What does CYL or cylinder mean on my prescription?
The CYL (or cylinder) on your prescription shows the extra strength needed at a specific angle to correct the vision of an eye with an uneven curve. This is only required for people with astigmatism.
Please note: Those without astigmatism won't find any figures written in their prescription cylinder or axis columns.
What does SPH or sphere mean on my prescription?
The term SPH or "sphere" in your prescription essentially tells you how strong the corrective lens needs to be for your eyes. This strength is measured in dioptres. If there's a minus sign before the number, it means you are nearsighted, implying difficulty seeing objects at a distance. On the other hand, a plus sign indicates farsightedness, where nearby objects may appear blurry.
If your eyesight doesn't fall into either category, you might come across an infinity symbol or the term "Plano" in the sphere column of your prescription. These essentially mean zero strength, suggesting that you don't require correction for nearsightedness or farsightedness.
What is the normal eye SPH, CYL, and axis value?
A ‘perfect’ eye, without any astigmatism, has both dioptric sphere power and cylinder power at 0.00. So, in summary, if everything is at 0.00, it's considered ideal.
What does it mean when your eye test says 0.50 in each eye?
When your eye test result reads 0.50 for each eye, it means you have a very mild prescription. This number can relate to different aspects of your vision correction. The three most common components are sphere, cylinder, and axis.
Sphere: This measures the overall strength of your prescription. A 0.50 in the sphere indicates a low level of nearsightedness or farsightedness.
Cylinder: If the 0.50 is found in the cylinder, it suggests a mild correction for astigmatism. Astigmatism occurs when the cornea or lens of your eye is not perfectly rounded/spherical in shape, causing blurry or distorted vision.
Axis: The axis is a number associated with the angle of astigmatism correction. In essence, the 0.50 measurement indicates a subtle need for correction in your vision. It's important to note that the higher these numbers go, the more significant the vision correction required. So, a 0.50 is considered very mild, and you may not experience severe visual disturbances.
Are Toric contact lenses the best for astigmatism?
Toric contact lenses are tailored for people with astigmatism, a condition where the eye has an irregular shape, causing blurry vision. Unlike regular contact lenses, toric lenses have a specific design, incorporating a cylinder and an axis. These details, mentioned on the packaging and your prescription, ensure a precise fit to address the unique shape of your eye. Essentially, toric lenses are like personalised tools crafted to correct astigmatism and provide clear vision.