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How to Read Contact Lens Prescriptions

How to Read Contact Lens Prescriptions

If you need vision correction, you might be torn between choosing eyeglasses or contact lenses. While both of these items are designed to help you see things more clearly, the prescriptions are completely different since they work in different ways. Read on to learn how to read your contact lens prescription so you know exactly what all of those numbers and letters mean.

Prescription Abbreviations

When you receive a written prescription for contact lenses from your eye doctor, you'll notice a bunch of different letters or abbreviations. Here is what each of these abbreviations stands for, but make note that your specific prescription may not contain all of them or have all of the sections filled out:

  • EYE: The eye section shows which eye your prescription line item is for. OD stands for the right eye, OS stands for the left eye, and OU means both eyes.
  • SPH: These letters stand for sphere, but you may also see the letters PWR for power here (both mean the same thing).
  • BC: The BC or base curve is usually listed as a number between 8 and 10 on your contact lens prescription.
  • DIA: This stands for the diameter, which is typically listed as a number between 13 and 15.
  • Brand: In this section, your eye doctor may fill out the brand of the contact lenses you're going to receive. This section is typically only filled out if you get fitted for your contacts during the exam visit.

Astigmatism Contact Lens Prescriptions

Toric contact lenses are specifically designed for correcting the vision of patients with astigmatism. You may notice different numbers and letters here since you'll need a few tweaks in order to see clearly. Two numbers separate by the letter X are usually listed and include CYL - the cylinder, and AX - the axis. The cylinder is usually accompanied by a number between -4.00 and +4.00, and the axis will show a number between 0 and 180.

Bifocal Contact Prescriptions

While it's rare, some people may require bifocal contact lenses or multifocal lenses. If this applies to you, your prescription will show an extra number and abbreviation. If you're getting bifocal or multifocal lenses, you will see the letters ADD, which stands for extra power, or extra strength.

Contact Lens Prescription Facts

Here are a few crucial facts to keep in mind when getting or reading a contact lens prescription:

  • Prescriptions for glasses and contacts are not the same, so you should never rely on your contact lens prescription if you decide to get glasses instead. Contacts usually require more information, and most of this relates to the size of the lens.
  • Your contacts sit on the surface of your eye while glasses sit a few millimeters in front of them. That's why the power of your lenses will be different than it is for your glasses.
  • Standard soft contacts cannot correct astigmatism. Your eye doctor will change the power of the lens in order to give you a prescription that will work for you.
  • Look for the expiration date on your contact lens prescription, which is usually about one year from the date you have the lenses fitted.
  • Your eye doctor will fit your lenses with the curvature that's most appropriate for each individual eye. This is known as the BC, or base curve.

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The material provided on this site is for informational purposes only and does not constitute medical or optometric advice. The information provided is not intended for the diagnosis of medical condition and should not substitute for the advice of a qualified health provider.

Please make sure you get your eyes examined regularly and always follow your eye care professional's instructions for the proper use and care of your contact lenses. It's important to note that if you experience any pain or discomfort from your contact lens, discontinue use immediately and consult your eye care professional. WARNING: IF YOU ARE HAVING ANY UNEXPLAINED EYE DISCOMFORT, WATERING, VISION CHANGE, REDNESS, OR LIGHT SENSITIVITY, REMOVE YOUR LENSES IMMEDIATELY AND CONSULT YOUR EYE CARE PRACTITIONER BEFORE WEARING YOUR LENSES AGAIN.

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