Prism Glasses: What Are They & Where to Buy Them

How much should prism glasses cost? It’s a question that’s confounding internet users.

While prism glasses sound like high-tech glasses that come with a high cost, that isn’t truly the case. This is technology that’s been around since the 1930s! 

Let’s find out more about prism glasses and where you can buy them without needing to empty your bank account!

At a Glance

• Reddit user MysteryVent was prescribed prism glasses, but they came with a $300 price tag from his optician. The Reddit community chimed in with affordable alternative sources for prism glasses, including Walmart and online eyewear retailers.
• Prism glasses are eyeglasses specially designed to correct double vision.
• They work by bending light so that when light enters your eye, it focuses on your retina each time.
• People with diplopia (double vision), people with eye muscle disorders, and those recovering from eye surgery can benefit from these glasses.
• You can buy prism glasses from optical shops, online retailers, and even discount stores. Just make sure you have an accurate prescription.

The Reddit Situation

While on Reddit, I happened upon a post by MysteryVent, asking about prism glasses. The Reddit Original Poster (OP) was mostly concerned about the cost. His glasses came with a $300 price tag!

MysteryVent said that he’s drowning in medical bills from a recent surgery, and the glasses offered were too expensive. He wanted a suggestion on where to get them affordably:

“Where do you guys get your prism glasses? Has anyone had luck online? I got prescribed prism glasses at the optometrist and they quoted me $300, Ive never needed glasses before and I unfortunately don’t have insurance and I am drowning in medical bills from a surgery early this year, not to mention I am going to have to find out how to pay for an MRI asap. I need suggestions for anything affordable please!”

The Reddit community was quick to chime in with cost-saving suggestions. A couple suggested getting the optometrist’s prescription so that the OP can get his glasses somewhere else. 

Metamoose1 said: 

“You could get a copy of the prescription and take it to a Walmart or other chain optical store that might have more deals, as long as it’s somewhere in person that they can measure the lenses so the prism is correct.”

This is a great idea. Walmart and other retailers, including those online, offer affordable options for those needing prism glasses. Also, as the patient, OP MysteryVent should get a copy of his prescription, whether he buys from his current optician or elsewhere.

An interesting warning came from user labmanagerbill. He said: 

“Do not order glasses with Prism online. I know it sucks to pay more, but you really need a professional to take accurate measurements in order for the Prisms to work correctly. You need an accurate monocular pupillary distance as well as an accurate optical center measurement. If any of these are off even a few millimeters, it can throw the prism off a noticeable amount.”

This struck me as odd, painting online eyeglasses shops as bad when they’re not the ones doing the measurements. Your optician should provide you with an accurate prescription. Once you have your prescription, you should be able to buy glasses anywhere you like.

Suggestions like this are unfair portrayals of online merchants and limit MysteryVent’s affordable options. Eyewear retailers with proper labs should be able to create prism glasses with no issue, as long as the measurements are precise.

What Are Prism Glasses?

Before we go further, let’s break down what prism glasses are exactly. Prism glasses are specialized eyeglasses that are designed to correct double vision (or diplopia).

This condition has several possible causes, including existing eye conditions such as astigmatism, cataracts, and macular degeneration. Some medical conditions also cause diplopia, such as Graves’ disease, strokes, and brain tumors.

Regardless of what’s causing your double vision, prism glasses can be a way to correct it.

How Do Prism Glasses Work?

To see clearly, light should enter your eye and focus on your retina, which is at the back of your eye. This is the signal for your brain to produce the images that you see in front of you.

In certain cases, however, some parts of your eye become too weak and cause the rest of your eye muscles to strain. This eye strain can cause headaches and double vision.

Prism glasses refract or bend the light that enters your eyes. This shifts the position of the image on the retina, helping compensate for the misalignment between the eyes.

Or, in other words, by bending the light, prism glasses help the brain merge the two images seen by each eye into one coherent image. Many people say that wearing prism glasses significantly helps reduce eye strain and fatigue.

Who Can Benefit From Prism Glasses?

Prism glasses are prescribed for problems that impact the way your eyes work together. When your eyes are not properly aligned, each eye can send a slightly different image to your brain. It can lead to double vision, eye strain, headaches, blurred vision, or trouble focusing.

People with binocular vision dysfunction (BVD)

Binocular vision dysfunction is a broad term for problems that stop the eyes from working together well. Even a small misalignment can cause symptoms such as eye strain, headaches, dizziness, and sometimes double vision.

Prism glasses can help by shifting the images reaching the eyes so the brain has an easier time combining them into a single image.

Individuals with eye muscle disorders

Your eye muscles keep your eyes coordinated so they can work together as a team. When muscle weakness or nerve damage prevents this from happening, your eyes can end up sending two different images to the brain, i.e., double vision.

Prism glasses don’t strengthen the eye muscles or fix the root cause. But they do compensate for the misalignment by changing the path of light entering the eyes. This shifts the images coming from your two eyes back into a single image like it’s supposed to be.

Post-surgery patients

Some people who have undergone eye surgery can temporarily or permanently experience double vision without correction. Prism glasses can be used to shift the two images back together as the eyes recover, or serve as long-term vision correction.

How To Read a Prism Glasses Prescription

If your eye doctor has prescribed prism glasses, you may notice some extra information on your eyeglass prescription that doesn’t appear on every prescription. Prism prescriptions include two key pieces of information: the prism power and the base direction.

Prism power

The amount of prism is measured in prism diopters, usually written with the symbol Δ. The number tells the lab how much the light needs to be bent to shift the image into the correct position. One prism diopter shifts an image by 1 centimeter at a distance of 1 meter.

A prism prescription might look something like 2Δ or 0.5Δ. Unlike the sphere or cylinder part of your prescription, it’s not written using a plus or minus sign. Instead, the number is paired with a direction that tells the lab how the prism should be positioned in the lens.

Base direction

The prism number tells the lab how much prism your lenses need. The base direction tells them which way to position it. You’ll see one of the four following abbreviations on your prescription next to your prism value:

• BU — base up: The base of the prism is positioned toward the top of the lens.
• BD — base down: The base is positioned toward the bottom of the lens.
• BI — base in: The base is positioned toward your nose.
• BO — base out: The base is positioned toward the side of the face, in the direction of your ears.

The lab needs both prism power and the base direction to read a prism prescription. The prism number tells them how much correction you need, and the base direction tells them which way that correction needs to be oriented.

For example, a prescription for 2Δ BO means 2 prism diopters with the base positioned outward. Your eye doctor may prescribe prism for one eye or both, and horizontal and vertical prism can be combined when needed.

So if you’re ordering prism glasses online, make sure they accept both the prism power and base direction.

What happens if you don’t enter your prism prescription?

If your prescription is left blank where it says prism, you don’t need to enter anything in the prism section when ordering your glasses.

But if your prescription does include prism and you leave that information out, your glasses will be made without that part of your prescription. The lenses might still correct your nearsightedness, farsightedness, or astigmatism. But they won’t shift the images in the way your prism correction is meant to.

If you were prescribed prism glasses to help with double vision, and you don’t fill out the info, you’ll probably still get double vision. And symptoms like eye strain, headaches, or visual fatigue will likely continue. So make sure you do fill it out.

Where To Buy Prism Glasses

As some of the Redditors mentioned, you can get prism glasses from optical retailers, online retailers, and even discount stores like Walmart. You aren’t just limited to where you got your prescription.

The key to buying these glasses confidently is to make sure your optician provides you with an accurate prescription. That’s it! Once you have your prescription, you can buy these glasses anywhere that suits your budget.

On EZContacts, it’s an option that you can choose when filling out your prescription details.

As you can see, it’s just a $29.95 add-on at EZContacts. If you’re working with a limited budget, just choose from the many bargain glasses on sale.

You can find frames starting at around $4.31 from brands like Peachtree. Basic plastic lenses are $39.95 at EZContacts, and the clear lens color is $9.95. And so, after you add in the $29.95 prism lenses, your total for these glasses would be $84.16. This is far less than the $300 quoted by Redditor MysteryVent’s optician.

What To Remember When Buying Prism Glasses

Keep this in mind when buying your prism glasses:

Prescription

Always get a proper eye examination and prescription from a qualified eye care professional. Prism glasses require precise measurements to be effective.

Type of Prism

There are different types of prisms (e.g., base-in, base-out) depending on your specific vision issue. Make sure your optician determines the best type for you.

Frame Style

Choose a comfortable frame that’s light and durable. You might need to wear them for extended periods in order to correct your eye condition.

Prism glasses are an effective solution to double vision. You just need to get a pair with perfectly accurate specifications for your unique requirements.

FAQs About Prism Glasses

How long does it take to adjust to prism glasses?

The initial adaptation usually takes two or three days, but for your brain to become fully adjusted, it can take up to two weeks. Early on, you might experience mild dizziness, eye strain, or trouble with depth perception as your eyes get used to the glasses.

To help the process along, wear the glasses consistently from morning to night. Avoid switching back to your old glasses, as this will slow down the adaptation. If double vision, severe headaches, or eye strain continue past 14 days, contact your optometrist, as there may be something wrong with the prescription or the glasses.

Do prism glasses work for all types of double vision?

No. Prism glasses are mainly used when a person has a certain type of binocular double vision, where an eye alignment problem causes the two eyes to send images that do not line up properly. They’re not a solution for every cause of double vision.

Are prism glasses more expensive than regular glasses?

Yes, they typically are. Prism lenses need to be customized specially in a lab. Adding a prism correction usually adds somewhere between $50 and $200+ to the cost of standard lenses. But at EZContacts, the cost is just $29.99 on any eyeglass frame.