Your eyeglass prescription is yours by law, and getting a copy is usually straightforward. Whether you need it from a recent exam, want to retrieve an old one, or are trying to decode what the numbers mean so you can order glasses online, there are several reliable ways to get what you need.
Your Eye Doctor Must Give It to You
Under the Federal Trade Commission’s Eyeglass Rule, your eye care provider is required to give you a copy of your prescription automatically after an eye exam, even if you don’t ask for it. You don’t need to pay an extra fee for the prescription itself, and the doctor cannot condition its release on buying glasses from their office. This means you’re free to take that prescription anywhere, whether it’s a competing optical shop, a big-box retailer, or an online glasses store.
If you’ve lost your copy, you can request it again. Under HIPAA, your provider must respond to a records request within 30 calendar days. If they need more time, they can take an additional 30 days, but they have to notify you in writing during that first window explaining the delay.
What’s on an Eyeglass Prescription
A standard eyeglass prescription includes your name, the exam date, an expiration date, and your doctor’s signature. The optical measurements are organized in a small table with a row for each eye. Your right eye is labeled O.D. and your left eye is O.S. If you see O.U., that refers to both eyes together.
Here’s what the columns mean:
- SPH (Sphere): The main lens power needed to correct your vision. A negative number means you’re nearsighted; a positive number means you’re farsighted.
- CYL (Cylinder): The amount of astigmatism correction, if any. Many people have at least a small amount. If this column is blank, you don’t have astigmatism that needs correcting.
- Axis: A number between 1 and 180 that indicates the angle of your astigmatism on the cornea. This always accompanies a CYL value.
- ADD: Additional magnifying power for reading or close-up work, used in bifocals and progressive lenses. This number is the same for both eyes in most cases.
Some prescriptions also include prism correction, which shifts the image your eye sees to help with double vision or eye alignment problems. Prism values come with a base direction: BU (up), BD (down), BI (in), or BO (out), telling the lens maker which way to orient the correction.
Where to Find Your Prescription if You’ve Lost It
The fastest option is to call the office where you had your last eye exam. Most practices can look up your records and read the prescription over the phone, email it, or have a copy ready for pickup. If you ordered glasses online previously, check your account on that retailer’s website. Many save your prescription on file.
Your health insurance portal sometimes stores vision records too, especially if your plan includes a vision benefit. It’s worth checking before scheduling a new exam just to get updated numbers.
When Your Prescription Expires
Eyeglass prescriptions don’t last forever. The expiration date is set by state law, and it varies. Most states set it at one to two years from the exam date. Once it expires, you’ll need a new eye exam before an optical shop or online retailer will fill an order. This isn’t just a bureaucratic hurdle. Your vision can change over time, and an outdated prescription may cause headaches, eye strain, or blurry vision.
Pupillary Distance: The Missing Measurement
One number you’ll need for ordering glasses online that often isn’t on your prescription is your pupillary distance, or PD. This is the distance in millimeters between the centers of your pupils, and it tells the lens maker where to place the optical center of each lens. Some doctors include it on the prescription; many don’t.
You can measure it yourself at home with a millimeter ruler and a mirror. Stand about 8 inches from the mirror, hold the ruler flat against your brow, then close your right eye. Line up the zero mark with the center of your left pupil. Without moving the ruler, close your left eye and open your right. The millimeter mark that lines up with the center of your right pupil is your PD. For the most accurate result, repeat this three times and average the numbers.
If someone can help, the process is even easier. Have them stand about 8 inches in front of you while you look straight ahead. They place the ruler on the bridge of your nose, align zero with the center of one pupil while you cover the opposite eye, then switch which eye is covered and read the measurement at the center of the other pupil.
Eyeglass vs. Contact Lens Prescriptions
If you wear contacts and have that prescription handy, you might wonder whether you can use it to order glasses. You can’t. The two prescriptions are written differently because of something called vertex distance, which is the gap between a lens and your eye. Glasses sit roughly 12 millimeters from your eye, while contacts rest directly on it. That difference changes the effective power of the lens, so the numbers won’t match, especially at higher prescriptions.
Contact lens prescriptions also include measurements that don’t apply to glasses, like the base curve and diameter of the lens. And astigmatism corrections differ: glasses can be ground to any precise axis, while contact lenses are manufactured in fixed increments, sometimes requiring slight power adjustments to compensate. So even if the sphere values look similar, filling a glasses order with contact lens numbers will likely give you the wrong correction.
Getting a New Prescription
If you can’t track down your old prescription or it has expired, a comprehensive eye exam is the only reliable path. These typically take 20 to 30 minutes and involve reading letters on a chart while the doctor flips through different lens options to find the clearest combination for each eye. You can get an exam at an optometrist’s private practice, an ophthalmologist’s office, or a retail vision center inside pharmacies and warehouse stores. Prices without insurance generally range from $50 to $250, depending on location and the type of practice.
Some online services now offer remote vision tests that can generate or renew a prescription through a smartphone app or computer screen. These work best for straightforward refractive corrections in people with healthy eyes. They typically won’t catch conditions like glaucoma or retinal problems, so they’re not a substitute for a full eye health exam, but they can be a convenient option if you simply need updated numbers and your eyes are otherwise healthy.