Skip to main content

Deciphering Your Contact Lens Prescription

For many users, contact lenses can be worn and then forgot about until it’s time to take them out again. However, because of the seeming simplicity of their use, it’s often overlooked that they are still a medical device and have specific instructions for comfortable wear. Below is a list of common questions about being fitted for, buying, and wearing contact lenses.

Are Eyeglass and Contact Lens Prescriptions the Same?

Contact and eyeglass prescriptions are not the same. They are significantly different because eyeglass lenses are positioned approximately 12 millimeters from your eyes, whereas contact lenses rest directly on the surface of your eyes.

So even if you already have an eyeglass prescription, you will need a separate contact lens prescription before you can purchase contacts.

Can Anyone Get a Contact Lens Prescription?

No, not everyone who needs eyeglasses can wear contact lenses successfully. Conditions such as dry eyes or blepharitis can make contact lens wear uncomfortable or unsafe.

Even with no pre-existing eye conditions, some people have sensitive corneas and simply cannot adapt to contact lenses.

Can You Buy Contact Lenses Without a Prescription?

No, under U.S. law the purchase of all contact lenses requires a valid contact lens prescription written by a qualified eye care practitioner.

This includes plano, or "non-prescription," colored contact lenses or special-effect lenses that are worn for cosmetic purposes only. Even for these, your eye care practitioner can only write your contact lens prescription after a thorough contact lens exam and fitting.

Why Do I Need A Prescription?

It is illegal to sell contact lenses without a prescription, and for good reason: a contact lens is a medical device, and a poorly fitted lens — or one made from a material not well-suited to your eyes — can cause distorted vision, discomfort, infection, inflammation, swelling and abrasion. In rare cases, permanent eye tissue damage could result.

Who Can Fit Me for Contact Lenses?

Throughout the U.S., you can be fitted for contact lenses by an optometrist or ophthalmologist. In some states, opticians also can be certified to fit contact lenses.

How Can I Decipher What’s On My Contact Lens Prescription?

Eye doctors use standard terms, abbreviations and measurements to write contact lens prescriptions. It may look like a secret code, but it's really quite simple to decipher. Click here for an interactive form explaining how to read each part of your content lens prescription.

Even If I Buy My Replacement Contacts from Another Source, Do I Still Need to Visit My Eye Doctor for Regular Eye Exams and Contact Lens Fittings?

Yes, when your prescription expires, you won't be able to buy more lenses until your eye care practitioner gives you an updated prescription. This will involve an eye exam to check your general eye health and to be certain that contact lenses aren't adversely affecting your eyes.

Just because your eyes feel good and your contact lenses seem to be working well does not mean your eye health is fine. You may be having microscopic problems that can be seen only with a type of microscope used during an eye exam.

How Often Should I Throw Away, Or Start Wearing New Contact Lenses?

Sometimes the lens brand includes information about the recommended replacement schedule, but the real judge is your eye care practitioner, who knows what's best for your eyes and lifestyle.

Where Can You Use Your Contact Lens Prescription?

Once you've been properly fitted by your eye doctor and have a valid contact lens prescription, you have the option of buying contact lenses from a wide variety of sources. These include your eye care practitioner, optical chains, warehouse clubs, mass merchandisers and online retailers.

Wherever you choose to purchase your contact lenses, always make sure you buy your contacts from a legitimate source. Vendors selling contact lenses without a prescription, such as you might find in a flea market, gas station or novelty shop, are breaking the law.