You’ve gone to the optometrist, had your eye exam, and now it’s time to get your prescription. When you look at it, though, you’re perplexed—what do all these letters and numbers mean? How do they tell you what kind of glasses you should get? How to Read your Eyeglasses Prescription?
Not to worry. Eye prescriptions can be confusing, but we’ll explain all of their different parts so you know how to read one. Not only will it help you understand your eyewear better, it also makes for an extremely practical party trick.
Your eyeglass prescription includes specific terms and numbers that indicate the corrections needed for your vision:
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OD, OS, and OU
- OD (Oculus Dexter): Information for your right eye.
- OS (Oculus Sinister): Information for your left eye.
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OU (Oculus Uterque): Refers to both eyes.
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SPH (Sphere) Indicates the lens power required to correct your vision:
- Nearsighted (Myopia): Marked with a minus (-) sign. Difficulty focusing on distant objects.
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Farsighted (Hyperopia): Marked with a plus (+) sign. Difficulty focusing on close objects.
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CYL (Cylinder) Specifies the lens power needed to correct astigmatism (difficulty focusing due to irregular cornea shape):
- Nearsighted Astigmatism: Marked with a minus (-) sign.
- Farsighted Astigmatism: Marked with a plus (+) sign.
Note: If your prescription has a CYL, it will always include an AXIS value.
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AXIS Defines the orientation of astigmatism correction:
- Measured in degrees, ranging from 0 to 180.
- This specifies the exact position of the astigmatism on your eye.
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ADD (Addition)
- Indicates additional lens power for reading or bifocal/varifocal glasses:
- Shows how much magnification is needed for close-up tasks or intermediate distances.
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PRISM Used to correct conditions like a lazy eye or squint:
- This adjustment shifts the focus of the lens to align the image properly on the retina.
- Included in prescriptions for special vision needs.
Eye Prescription Scale
Diopters: Any numbers you see in the “Sphere” or “Cyl” column of your eye prescription stand for diopters. A diopter is a unit of measurement, like a gram or an ounce. Instead of measuring mass, however, diopters measure the refractive power of a lens. You’ll see larger numbers (more optical power!) if your prescription is higher and lower numbers if your vision doesn’t need as much help from glasses or contacts.
It’s important to note that these numbers proceed in either direction on a number line—they can be positive or negative, based on the type of refractive error in your eye. If you don’t need glasses at all, you wouldn’t need any optical power from lenses: 0 diopters.
Negative Numbers: If you see a minus sign in front of a number, that indicates nearsightedness, or myopia. Someone with -3 diopters of nearsightedness, for example, might have trouble reading words on a chalkboard from far away.
Positive Numbers: If you see a plus sign in front of a number, that indicates diopters that will correct farsightedness, or hyperopia. Someone with +3 diopters of farsightedness, for example, might struggle to read text that’s very close to their face.
Expiration Date: Your eye prescription probably won’t be the same forever—it’s important to have your eyes examined regularly to make sure they’re seeing as best as they possibly can.
Eye prescriptions are normally valid for a year or two before they expire (the exact time period can vary depending on state laws). After that, you’ll need to renew it by scheduling an eye exam. Hope this will help you learn How to Read your Eyeglasses Prescription?
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