Understanding Your Contact Lens
Prescription

By Liz Segre

Before 2004, only consumers in certain states were entitled to a copy of their contact lens prescription. Then legislation was passed requiring that all U.S. consumers be given a copy of their contact lens Rx (click here for the text of the 2004 legislation).

Now wearers in all 50 states have the option of buying contact lenses from their eye care practitioner (ECP) or shopping around at various optical chains, warehouse clubs, and Internet sites.

Can I Get Contact Lenses Without a Prescription?

No, you cannot get contacts without a prescription. The 2004 legislation does not eliminate ECPs from the process of fitting and prescribing contacts. In the United States, contact lenses are a prescription item, just like medicines. And even if you already have an eyeglass prescription, you need a contact lens prescription that contains additional information.

The 2004 law changed how you can buy the lenses themselves, after you've been properly fitted. It's an important distinction, now that most people wear disposable contact lenses and need to purchase a supply of lenses on a regular basis.

Why a Prescription?

A contact lens is a medical device. If it's not prescribed properly, you may not see well. More importantly, a poorly fitting lens — or one made from a material not well-suited to your eyes — can mean discomfort, inflammation, swelling, abrasion, or another problem that could, in rare cases, result in permanent eye tissue damage.

That, and the risk of infection, are also why it's a bad idea to share contact lenses with other wearers.

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

When Does Your Rx Expire?

By law contact lens prescriptions are valid for a minimum of one year, or the minimum required by state law, whichever is greater.

Even if you buy your replacement contacts from another source, you still need to visit your eye doctor for regular eye exams and contact lens fittings.

When your prescription expires, you won't be able to buy more lenses until you get an updated prescription. This will probably involve a checkup by your ECP 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 O.K.," says Charles Slonim, MD, an ophthalmologist in Tampa. "You may be having microscopic problems that can be seen only with a slit lamp [a type of microscope used during an eye exam]."

Dr. Slonim says that about 10 percent of the time when he sees a patient during a follow-up visit, he notices something that could become a problem if not taken care of immediately.

Remember, if you're diagnosed with a lens-related problem, it's unlikely that you'll have to permanently discontinue wearing contacts. Chances are you'll simply need a different size, material or design of lens.

Interpreting Your 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.

Below is an example of a contact lens prescription. Place your cursor over each element, and it will be explained on the right:

In addition to the above information, your prescription may note how often your contact lenses must be replaced (once a month, every two weeks, once a week, daily, etc.). Or you may be instructed verbally, during your exam. Often the lens brand includes this information (e.g., Ophtha-Lens One-Week), but the real judge is your eye care practitioner, who knows which replacement option is best for your eyes and lifestyle.

[Page updated October 2009]