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Online tools can help find existing glasses prescriptions without an exam. Here’s a hands-on review of one app to do just that, plus other top picks.

Over 150 million people in the United States wear corrective eyewear designed to compensate for nearsightedness and farsightedness.

If you’re one of them, you know how expensive and time-consuming it can be to get a prescription and new glasses. Eyeglass prescriptions usually last from 1–2 years. If it’s been that long since you got your prescription, it may be better to see an eye doctor for a health checkup and to get your most up-to-date prescription and best fit.

If you have eyeglasses and are confident the prescription is up-to-date, you can try the GlassesUSA Prescription Scanner appto get your prescription details.

Keep in mind that the accuracy of apps like this to measure eyeglasses is unknown and depending on your prescription, this may not be the best way to measure the prescription of your eyeglasses.

As the author and hands-on reviewer, I’m detailing the steps I took when trying to use the GlassesUSA Prescription Scanner app, as well as other options folks have for figuring out your glasses prescription.

The GlassesUSA Prescription Scanner is a free app that uses your smartphone camera to scan your current eyeglasses and read the prescription. You’ll also submit a selfie photo to measure your pupillary distance (PD), the distance between your pupils.

Scanning lenses that GlassesUSA doesn’t make

I knew that GlassesUSA wasn’t designed for my type of prescription, but out of curiosity, I completed the scan using my eyewear.

How the first scan went

After doing all the steps, a screen indicated that my glasses were out of range and couldn’t be read.

Even though this confirmed that I couldn’t use the app, it was good news because it showed that the GlassesUSA app read my prescription correctly and gave me accurate information that couldn’t be fulfilled.

How the second scan went

I tried it a second time with my eyewear to get a better handle on all the screens.

I was surprised that this second try brought a different result. The app took me through the entire process, and I continued to try to read my prescription at 99 percent complete for over 20 minutes. It never finished and never sent me an error message.

Scanning lenses that GlassesUSA can make

Next, I borrowed a pair of eyeglasses from my nearsighted son, who has a simple prescription that fits within the GlassesUSA range. This range is for single vision prescriptions between -6.00 to +3.00 and cylinders up to -2.50.

Then, I reviewed the steps I took with his glasses using the GlassesUSA app.

You can read more about the Prescription Scanner app on GlassesUSA.com.

1. Download the GlassesUSA app

  • From its website. Open up the GlassesUSA website on your computer. Toward the bottom of the homepage, there’s a “download app” prompt where you can request the app link.
  • From the app store. You can also download the GlassesUSA app directly through the app store on your phone. It’s available for both iOS and Android.

2. Scan from the app

Once the app is opened, click “Start scan.” The app uses voice prompts to get you from one step to the next, which is very helpful.

3. Collect what you’ll need

The screen will show the tools you need to complete the scan. These are:

  • computer with a screen that measures 12” x 27”
  • standard magnetic card for scaling
  • your eyeglasses

What’s a ‘magnetic card’?

Cards with magnetic strips are generally the size of a standard credit card. These include gift cards, debit cards, and ID and transit cards.

GlassesUSA describes using a “magnetic card” to take certain measurements and images for the scanning app.

We suggest using something without identifying markings and without account information on it.

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4. Set up and calibrate your device

You’ll receive a web address to log into from your computer, where you’ll see a QR code to scan. This syncs your phone to your computer.

If your computer doesn’t have functional cookies enabled, you won’t be able to complete this step. While cookies were enabled, I couldn’t complete this step in Google Chrome. I tried Chrome on another computer but got the same result. I had better luck with Microsoft Edge and could scan the QR code.

Once the code is scanned, you’re prompted to scale the exact size of your computer screen using a magnetic card. This sounds easy, but it may take several tries before it calibrates. If it doesn’t work instantaneously, you’ll have to hold the card flat against the screen. I had to adjust the screen up and down many, many times before it calibrated. This took multiple tries on two computers for around 15 minutes.

5. Scan your current pair of eyeglasses

Once things are calibrated, the app is ready to scan your glasses. You do this by holding your glasses midway between your phone and computer. You’ll be prompted to tilt your glasses repeatedly until they’re read. This takes around 3 minutes.

6. Take a photo for your PD measurement

You’ll be asked to take a selfie with the magnetic card between your eyebrows. This is done to measure your pupillary distance (PD). This vital step ensures that the lens power of your eyewear is correctly centered.

GlassesUSA will then request your account information and provide you with your prescription so you can purchase glasses.

If you have a prescription on hand to compare your GlassesUSA prescription, you can be better assured of its accuracy.

Privacy, please!

If information privacy is a concern to you, use any card that is credit-card sized (such as a library card) or cover information like numbers and names.


  • straightforward and easy to use
  • fast and convenient process in the comfort of your home
  • less expensive than visiting your eye doctor


  • errors can cause inaccurate prescriptions
  • your prescription may have changed
  • not suitable for strong and progressive prescriptions
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The GlassesUSA Prescription Scanner app is suitable for:

  • people aged 18 years and older who have simple prescriptions
  • people with stable vision are satisfied with their current prescription
  • single vision prescriptions between -6.00 and +3.00
  • cylinder measurements lower than -2.50

It’s necessary to have a smartphone with a working camera, a desktop or laptop computer with at least a 12-inch (30-cm) screen, and a standard-size magnetic card. Plus, you’ll need your eyeglasses with your current prescription.

GlassesUSA has a 4.4 (5 star) rating on Trustpilot. GlassesUSA is accredited by the Better Business Bureau (BBB) and has an A rating. Customer reviews on the BBB website give GlassesUSA an average rating of 2.08, and there were 412 complaints closed in the last 12 months.

Positive reviews say the Prescription Scanner app is convenient to use, the process is smooth, and their prescriptions are accurate. Customers are satisfied with the wide selection of glasses and reasonable prices.

Many unfavorable reviews mention:

  • shipping delays
  • refund issues
  • poor customer service communication
  • hidden charges
  • the short 14-day return window
  • receiving faulty products

Remember to request your prescription details from the office where you last had an eye exam. They’re required to share a copy with you.

If you’re looking for other options to find out your prescription based on existing glasses, there are other scanning apps like the one GlassesUSA offers.

  • Liingo RX Reader: Liingo Eyewear also has an app you can use to get a prescription for your current glasses by downloading the app, calibrating hardware, and scanning your lenses.
  • GlassesOn app: 6over6 offers its GlassesOn app to take measurements similar to GlassesUSA Prescription Scanner to get PD and lens details.
  • Lens Scanner App: SmartBuyGlasses, an eyeglass retailer, partnered with 6over6 to offer its own version of an eyeglass scanning app.
What the Prescription Scanner app isn’t for

The app doesn’t accommodate:

  • strong or weak prescriptions
  • prism prescriptions used to correct double vision
  • multiple prescriptions within one lens, such as bifocals or multifocals
  • contact lens prescriptions

Pupillary distance (PD) is indicated on the inside of your glasses, but in a roundabout way. You’ve probably noticed three sets of numbers on the inside of your frames. In this order, they are:

  • eye size number (the size of your lenses on your frame)
  • bridge size number (the distance between each lens)
  • temple length number (size of the frames)

To get your PD, add together the temple length number (frame size) with the bridge size number. For most brands, that will give you your PD. A word of caution, however – if you have to measure your PD to purchase online glasses, utilize the prescription tool provided by the seller. This is the only way to truly ensure accuracy.


No, the information you provide to the Prescription Scanner app is not reviewed by a qualified healthcare professional. GlassesUSA does not offer medical advice.

According to the American Academy of Ophthalmology, eyeglass prescription apps and home vision tests are suitable for people 18–39 years old with healthy eyes and a mild or moderate prescription.

But they are not advisable for people who have a strong or complicated prescription, an eye condition, or a condition that increases their risk for eye disease, including diabetes or a family history of glaucoma.

Anyone who hasn’t had an eye examination for 1 to 2 years should visit an eye doctor to update their prescription.

The prescription measurements from the GlassesUSA app are fairly accurate though the exact accuracy is unknown. But the app has a higher margin of error and is less accurate than tests that an optometrist or ophthalmologist performs.

There are several symptoms that may suggest it’s time to visit an eye doctor for an updated prescription, including:

  • headaches
  • blurry vision
  • eye fatigue

If it’s been more than a year since your last eye exam, it’s time to make an appointment, too.

Your eye prescription will likely change throughout your life. If you have any issues with your eye health or vision, try to visit your eye doctor every year for an updated prescription.

Your eye doctor will perform a comprehensive exam and let you know whether your prescription has changed.

It’s possible to have multiple eye prescriptions at once. This may happen if your eye doctor prescribes bifocal or multifocal lenses.

These lenses contain more than one prescription within the same lens to help you see clearly at different distances.

There are several online retailers, including GlassesUSA, where you can have your current eyewear prescription read.

Some retailers also offer vision checks, which ophthalmologists assess. But according to the American Academy of Ophthalmology (AAO), these aren’t as accurate as in-person exams and these vision checks don’t assess eye health.

These services may be less expensive for purchasing eyewear than some brick-and-mortar retailers.

They are typically best for simple prescriptions. If you wear bifocals or have any other type of complex or strong prescription, seeing an eye doctor in person may be your best first step.

Once your prescription is in hand, you can use an online retailer, if you choose.