Can You Buy Contacts with a Glasses Prescription?

When it comes to vision correction, many people wonder if they can use their glasses prescription to buy contact lenses. Let’s delve into this topic to understand the relationship between glasses and contact lens prescriptions.


Photo by Pavel Danilyuk

Understanding Prescription Differences

Glasses and contact lenses serve the same purpose of correcting vision, but the prescriptions for each are different.

  • Glasses Prescription: A glasses prescription is typically written to correct vision at a specific distance from the eyes. It includes values for Sphere (SPH), Cylinder (CYL), and Axis. Sometimes there will also be an add power or prism correction.
  • Contact Lens Prescription: Contact lenses sit directly on the eye’s surface, so their prescription includes additional factors like base curve (BC) and diameter (DIA), which are crucial for proper fit and comfort. Contact lens prescriptions also adjust for the distance between the cornea and the lens.


Photo by Karolina Kaboompics

Can You Use a Glasses Prescription for Contacts?

In general, you cannot directly use a glasses prescription to buy contact lenses. Here’s why:

  • Different Measurements: Contact lenses require specific measurements like base curve and diameter, which are not included in a glasses prescription.
  • Eye Health Considerations: Contact lenses sit directly on the eye, so their fit is crucial for eye health and comfort. An accurate contact lens prescription ensures proper fit and reduces the risk of complications.
  • Vision Needs: The way light refracts through glasses versus contact lenses differs due to their placement relative to the eye. Therefore, the prescriptions are tailored accordingly.

Getting a Contact Lens Prescription

To get contact lenses, you will need a contact lens exam. Your eye care professional will conduct this specialized exam to ensure that a specific brand of contact lenses fits properly on your eye. During the exam, they will assess factors such as the curvature of your eye and the prescription strength needed to correct your vision. This thorough evaluation is essential for determining the right type of contact lenses that will provide clear vision, comfort, and maintain your eye health.

Can You Convert Your Glasses Prescription?

While you can’t use a glasses prescription directly for contacts, your optometrist can use your glasses prescription as a starting point. They will perform additional tests to determine your contact lens prescription accurately.

Importance of Regular Eye Exams

Whether you wear glasses or contact lenses, regular eye exams are crucial. They ensure your prescription is up-to-date and your eye health is monitored. Eye conditions can change over time, affecting your prescription needs.


Photo by Antoni Shkraba


While glasses and contact lenses both correct vision, their prescriptions are not interchangeable. Contact lenses require specific measurements and considerations for proper fit and eye health. If you don’t have a contact lens prescription, we recommend scheduling a contact lens appointment with your eye doctor.

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Ivan Yong

Dr. Ivan Yong is an optometrist with over 12 years of experience in the optical industry. He earned his doctorate from the Southern California College of Optometry and has practiced in multiple settings, including private practice, community health, and ophthalmology. Dr. Yong aims to expand access to affordable eyewear and improve eye health worldwide.