Eyeglasses are wearable accessories and medical devices that help you see. They adjust light before it enters your eyes, making up for what your eyes can't do. They help you see clearer at variable distances. And the prescription of your lenses can be tailored to meet your exact vision needs.


What are eyeglasses?

Eyeglasses are wearable lenses mounted in a frame you wear on your face so you can see better. They do that by correcting refractive errors (like nearsightedness) or other issues that make it hard for you to see properly. Corrective lenses in prescription and reading eyeglasses get their name from how they “correct” your eyesight. They compensate for what your eyes can’t do on their own so you can see clearly.

Eyeglasses (often known simply as “glasses” or “spectacles”) can help with a variety of vision issues. That includes difficulty seeing objects up close, far away or at varying distances. They can also help with distortions in your vision, age-related vision difficulties and eye alignment issues.


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What do eyeglasses do?

Eyeglasses do for your eyes what a stepstool does for how high up you can reach. They help you use an ability that isn’t strong enough on its own.

When beams of light enter your eyes, they pass through the cornea and lens. The cornea and lens are supposed to bend light beams so they converge on the retina at just the right distance. When they do this correctly, your vision is clear and sharp.

But if you have a refractive error (either in one or both eyes), the affected eye(s) can’t bend beams of light correctly, making things look blurry and out of focus. That’s where eyeglasses come in. They add more bend to the light than your eyes can do on their own.

Eyeglasses can also help with double vision (diplopia) because of eye misalignment. When your eyes align correctly, your brain can seamlessly “fuse” input from both eyes into a single picture. When your eyes don’t align correctly, you get double vision because there are two competing pictures. Certain types of lenses can compensate for that.

What can eyeglasses help with?

There are four main types of refractive errors that eyeglasses can help:

How common are eyeglasses?

Eyeglasses are extremely common. Over 1 billion people around the world wear them.


What tests will I need before getting eyeglasses?

Before you get prescription glasses, you’ll need to undergo an eye exam. An eye care specialist, usually an optometrist or ophthalmologist, will do the exam and associated tests to check your sight. They’ll check if you have 20/20 vision (in places that use the metric system, it’s 6/6 vision).

Having 20/20 vision means your visual acuity is normal. If you don’t have 20/20 vision, your eye care specialist will determine how far off from 20/20 you are and what it’ll take to get you up to that. And if you already wear glasses, they’ll make sure your glasses are helping you adequately.

Not having 20/20 vision can go one of two ways:

  • If the second number is less than the first: This is better-than-normal vision. For example, 20/15 vision means you can stand 20 feet away from something and see it clearly. Meanwhile, most people would have to get closer and stand 15 feet away to see it just as clearly as you.
  • If the second number is greater than the first: This is worse-than-normal vision. For example, 20/30 vision means most people could stand 30 feet away from something and see it clearly. But you would need to stand closer, 20 feet away, to see it just as clearly as they do.

What are the different types of prescription eyeglasses?

There are many different varieties of eyeglasses. Some of the terms you might encounter include:

  • Single-vision lenses. These are lenses with a single prescription change.
  • Multifocal lenses. These are lenses with multiple prescriptions combined into a single lens. For example, a multifocal lens can have a prescription for close-up reading and another for seeing farther away.
  • Bifocals. These are a type of multifocal lenses. “Bi-“ means they contain two different prescriptions. They usually contain a visible seam/edge that separates the prescriptions (they often look like a lens within a lens).
  • Trifocals. These are also a type of multifocal lens. “Tri-“ means they contain three different prescriptions. These also usually have a seam between the different prescriptions, appearing like multiple lenses combined into a single piece.
  • Progressive lenses. These are somewhat like bifocals, but there’s no seam. The prescription gradually changes from top to bottom. The lower part of the lens helps with close-up vision.
  • Reading glasses. These are single-vision lenses that help with near vision. Their main use is helping people with presbyopia see up close for tasks like reading. Many people know them as “readers” or “cheaters” (a slang term from the 1920s that’s still in widespread use). You can often purchase these over the counter (OTC) at pharmacies, grocery stores and bookstores.
  • Prism lenses. These lenses shift the light’s position before it enters your eye. That position shift helps with double vision due to eye misalignment.

Some types of lenses or glasses have very specific uses. You can often get these without a vision prescription in the lens, or as a prescription lens with the various features/capabilities built in. They include:

  • Sunglasses. Sunglasses can have prescriptions built into the lens. This can be helpful if you need to wear glasses all the time and want to make it easier to block sunlight and see clearly at the same time.
  • Computer glasses. Sometimes known as “blue-blockers” (or under the trademark “BluBlocker®”), these glasses block certain wavelengths of light. If you spend a lot of time looking at a computer screen, they can help ease eye strain and fatigue. You can also commonly get a blue-blocking coating on prescription lenses of any kind for this same reason.
  • Photochromic lenses. These are also known as “light-adaptive” lenses or under the trademarked name “Transitions®.” They automatically darken when ultraviolet light hits them. The material can be part of the lens itself or in a coating applied to the lens’ surface.


What are the different types of lenses and lens materials?

When it comes to prescription lenses, you often have two choices: glass or plastic. Your eye care specialist or another eye care professional, like an optician, can tell you more about the options available. They can also explain the pros and cons, and tell you what different types of glass might do for you.

Glass lenses
Plastic lenses
Easier to crack or break.
Plastic lenses
More durable.
Harder surface (doesn’t scratch easily).
Plastic lenses
Softer surface (easier to scratch).
Harder to apply coatings.
Plastic lenses
Easy to apply coatings for many reasons.
High-index (for stronger prescriptions) available.
Plastic lenses
High-index (for stronger prescriptions) available.

There are also a few different varieties of plastic available for use in prescription lenses. They all scratch easier than glass, but anti-scratch coatings help offset that disadvantage.

Common plastic materials include:

  • Standard plastic. The most common plastic for prescription lenses is Columbia Resin #39 (known simply as “CR-39®” for short). CR-39 weighs half as much as glass, which helped it become a popular lens material.
  • Polycarbonate. This type of plastic is light and yet very durable, and it’s more shatter-resistant than CR-39. The lenses can be even thinner and lighter than with CR-39, too. This material is especially popular for very active people, including kids. They’re also good for people with strenuous jobs where you’re more likely to damage your glasses.
  • Trivex®. This is the lightest of the plastic materials available for prescription lenses. It’s also impact-resistant.
  • High-index plastics. Similar to varieties of high-index glass, high-index plastics are useful for stronger prescriptions. But like their glass counterparts, high-index plastics also have durability issues and are prone to breaking.

Risks / Benefits

What are the advantages of eyeglasses?

While eyeglasses don’t fix the underlying issue, they do compensate for the problem while it’s happening so you can go about your usual routine and activities.

Specific advantages include:

  • They work. The history of eyeglasses goes back centuries. And technological advances mean modern eyeglasses can be lighter, less expensive, more durable and better at helping you see.
  • They’re safe. Eyeglasses pose little to no risk to your health and safety.
  • They can help with a wide range of eye issues. Eyeglasses can help with all forms of refractive errors. And the various ways of making lenses mean they can treat multiple issues at once. Some examples include bifocals and trifocals, or glasses that can treat both astigmatism and far-or nearsightedness at the same time.
  • The underlying technology isn’t expensive. Eyeglasses can be made at a very low cost, depending on the techniques and materials used.
  • Insurance coverage is widely available. Vision insurance plans are common and cover much of the cost of lenses and frames.
  • Cost assistance programs may be available. Depending on where you live, programs may help cover or lower the cost of eye exams, glasses or related needs if you don’t have insurance or your insurance doesn’t fully cover the costs related to your eyeglasses.

How long does it take to adjust to new glasses?

Adjusting to new glasses usually takes only a few days. But certain prescription adjustments (like prism changes to help with eye alignment) may take longer to get used to. Your eye care specialist is the best person to tell you what to expect with your prescription.

How do I care for my glasses?

When you’re not wearing your glasses, the best place to store them is in a hard-shell eyeglasses case. That will protect them from the most common causes of damage, like drops, scratches and more. If you don’t have that kind of case handy, a clean, dry place away from anything that could scratch or otherwise damage them will do, too.

To clean your glasses, keep in mind the following:

  • Wet your glasses first. You can use mild dish soap and water or a mild isopropyl alcohol spray (make sure first to ask your eye care provider or another professional if alcohol spray can damage your lenses).
  • Use the appropriate type of fabric. A microfiber towel or another type of lint-free cloth is best. NEVER use paper towels, facial tissue, toilet paper, etc. Those are all wood-based paper products, which can scratch the surface of your glasses or damage protective coatings.
  • Don’t use your clothes. Using a sleeve or corner of your shirt to clean your glasses can be tempting and convenient. But that’s not the best way to ensure your glasses stay in top condition. Fibers in clothing, like cotton or synthetic fibers, might also scratch, scuff or damage the coating on your lenses.

When To Call the Doctor

If I wear glasses, how often do I need an eye exam?

Everyone needs an eye exam at least once every one to two years. You might need to see your eye care specialist more frequently if you have certain medical conditions or circumstances. If you have questions about how often you should see your eye specialist, ask them. They can offer options and schedule you in a way that’s more convenient for your schedule and needs.

How often should I change my glasses?

Your eyeglasses need to change when your prescription changes. If your prescription changes very little or not at all, you can keep using the same glasses as long as they still work well and don’t have any damage or other issues.

When should I call my eye care specialist?

You should call your eye care specialist anytime you notice changes in your vision or symptoms/issues that could be related to your vision. That includes your eyes feeling tired or strained, headaches, eye pain, light sensitivity, etc.

Additional Common Questions

What are the side effects of wearing eyeglasses?

Eyeglasses have very few side effects when correctly made and used. Some examples of mild side effects that you might want to address include:

  • Lens-related issues. Getting used to a new prescription lens may take a few days, depending on how much they change your vision from what you’re used to. And some types of lenses, such as progressive lenses, have small distortions near the outer edge because of how the lens is made. If you’re having trouble adjusting to this, ask your eye care specialist for help or suggestions.
  • Fit-related discomfort. In some cases, wearing glasses may lead to mild discomfort anywhere the glasses touch your head or face — especially your nose, ears or temples. Getting the frame adjusted is usually the solution. You may want to ask your eye care specialist or their staff about their services for minor adjustments or repairs like this.
  • Eye strain or headaches. If you have a brand-new prescription or an out-of-date one, you might notice your eyes feel tired or you’re having headaches more often, especially if you do a lot of reading or computer work. If your prescription is new, this usually goes away after a few days or so. If your prescription is out of date (more than a year or two old), this is usually a sign you need to get a new prescription.

And in contrast, the side effects of not having corrective eyewear are far more severe. Uncorrected vision issues can contribute to:

  • Decreased mobility.
  • Trouble with activities of daily living (ADLs) like bathing, dressing, feeding yourself and others.
  • Decreased work productivity.
  • Increased risk of mental decline.
  • Increased risk of mental health issues, especially depression.

How much do eyeglasses cost?

The average one-time cost for getting eyeglasses, including an eye exam, the lenses and the frames, is about $398. For some people, that’s no big deal. For others, that cost might be out of reach or difficult to take on. It depends on many factors, including vision insurance and if there are cost assistance programs or resources that can help you.

But at the same time, the estimated cost of uncorrected vision is far greater. Experts estimate the cost — directly or indirectly — from uncorrected vision is $5,317 per person each year.

Can I save money by ordering glasses online?

Possibly. Ordering glasses online can save you money, but you should keep a few things in mind before you do so.

  • Make sure your eye exam results and prescription are current. You’ll need this to get an accurate prescription. And remember, online eye tests or apps aren’t a substitute for seeing a trained eye care specialist for your exam. If your prescription is more than a year or two old, it’s out of date.
  • Hold onto the paper copy of your prescription. In the U.S., your eye care provider legally MUST give you a paper copy of your prescription at no extra charge, even if you don’t want it. (The U.S. Federal Trade Commission calls this the “eyeglass rule.”)
  • Know your eye distance measurements. One of the most important is your pupillary distance. Some states require this to be included in your prescription, but most states don’t. You can ask for it and see if your eye care provider will give it to you. Knowing that measurement can help make sure your glasses are made properly.
  • Ask if you can bring your own frames. Some eyeglass providers will let you provide your own frames. Call ahead and ask if they’ll do this, and if the answer is yes, buy frames on your own. That could help you save a lot of money.
  • Read the fine print. Eyeglass maintenance details and warranties can save you money in the long run. Make sure you know if they cover frames, lenses or both. It may add some cost early on, but it could save you the full cost of a new pair of glasses later on. And if you have a stronger or very specific prescription, don’t hesitate to ask questions. It’s important to understand how your prescription will affect the cost of your glasses.

Will I damage my vision by not wearing my glasses?

Probably not. Children may have worsening vision issues because of early growth and eye shape changes, but that usually stabilizes in adulthood. And older adults with presbyopia may have a decline in up-close vision, but that’s generally expected with aging to begin with.

A note from Cleveland Clinic

The answer to your vision issues could soon be sitting right on the front of your face. Eyeglasses are a tried-and-true method for helping you see better. If you think you might need glasses, talk to an eye care specialist. They can help you understand the steps that need to happen for you to get glasses. They may also be able to help you find resources to help manage the costs.

Medically Reviewed

Last reviewed on 02/21/2024.

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