Adam Torkildson
If you wear glasses or contact lenses, then you must have a prescription that specifies your vision correction needs. However, understanding the terms and numbers in your prescription can be confusing. Therefore, we will break down the components of how to read eye prescription and help you understand what they mean.
What is an Eye Prescription?
An eye prescription is a written order from an optometrist or ophthalmologist that specifies the type and amount of corrective lenses needed to improve your vision. It typically includes a range of numbers and abbreviations that can be difficult to decipher.
Getting an eye prescription is an important step in ensuring that you have clear and comfortable vision. Whether you are getting glasses or contact lenses for the first time, or you need to update your prescription, understanding the components of your eye prescription is crucial.
Understanding the Components of Your Eye Prescription
Eye prescriptions consist of several components, each of which provides specific information about your visual needs. Here are the key components that you will find in your prescription:
OD and OS
OD and OS are abbreviations for the Latin terms “oculus dexter” and “oculus sinister,” which mean “right eye” and “left eye,” respectively. These abbreviations indicate which eye each component of the prescription applies to.
It’s important to note that the order in which the numbers appear in your prescription may vary. However, the OD and OS values will always be clearly labeled to indicate which eye each component applies to.
Sphere (SPH)
The sphere value in your prescription indicates the amount of lens power needed to correct your nearsightedness or farsightedness. A negative number (-) represents nearsightedness, while a positive number (+) indicates farsightedness. The higher the number, the stronger the lens power required.
The sphere value is the most important number in your prescription as it indicates the amount of correction needed for your vision. It’s important to note that while a higher number indicates a stronger lens power, it does not necessarily mean that your vision is worse.
Cylinder (CYL)
The cylinder value in your prescription indicates the amount of lens power needed to correct astigmatism, which is a condition that causes blurry or distorted vision. A negative cylinder value corrects nearsighted astigmatism, while a positive value corrects farsighted astigmatism.
If your cylinder value is zero, it means that you do not have astigmatism. If you do have astigmatism, the cylinder value will indicate the amount of correction needed to improve your vision.
Axis
The axis value in your prescription indicates the orientation of the cylinder component needed to correct your astigmatism. It is measured in degrees from 1 to 180.
The axis value is important as it indicates the direction in which the lens needs to be oriented in order to correct your astigmatism. It’s important to note that the axis value is only relevant if you have a cylinder value in your prescription.
Prism
The prism value in your prescription indicates the amount of lens power needed to correct eye alignment problems, such as double vision. It is measured in prism diopters (p.d.).
The prism value is only included in your prescription if you have eye alignment issues that require correction. If you do have a prism value, it is important to provide this information to your eyewear provider to ensure that your lenses are made to the correct specifications.
Add
The add value in your prescription indicates the additional lens power needed to correct presbyopia, which is a condition that affects near vision in people over the age of 40. It is usually a positive number and is added to the sphere value for reading glasses or bifocals.
The add value is only included in your prescription if you have presbyopia. If you do need reading glasses or bifocals, the add value will indicate the amount of additional correction needed for near vision.
How to Read Your Eye Prescription
Now that you know the key components of your eye prescription, here’s how to read it:
- Start with the OD and OS values to determine which eye each component applies to.
- Look for the sphere value, which indicates whether you are nearsighted or farsighted.
- If you have astigmatism, look for the cylinder and axis values.
- If you have eye alignment problems, look for the prism value.
- If you need reading glasses or bifocals, look for the add value.
It’s important to note that your prescription may include additional information, such as a base curve or pupillary distance. These values are important for ensuring that your lenses are properly fitted to your eyes.
Here is an example of how to read an eye prescription:
OD: -2.50 -1.00 x 180
OS: -2.25 -0.75 x 170
In this example, the patient has nearsightedness with astigmatism in both eyes. The sphere values (-2.50 and -2.25) indicate the lens power needed to correct the nearsightedness, while the cylinder values (-1.00 and -0.75) and axis values (180 and 170) indicate the lens power needed to correct the astigmatism.
What to Do with Your Eye Prescription
Once you have your eye prescription, you can use it to order glasses or contact lenses. Be sure to provide the correct information to your eyewear provider to ensure that your lenses are made to the correct specifications.
It’s also important to note that your eye prescription may change over time, so be sure to have your eyes checked regularly by an optometrist or ophthalmologist.n needs.
