Pinhole glasses are typically eyeglasses with lenses that are full of a grid of tiny holes. They help your eyes focus by shielding your vision from indirect rays of light. By letting less light into your eye, some people can see more clearly. Pinhole glasses are also called stenopeic glasses.

Pinhole glasses have several uses. Some people use them as a treatment for myopia, also known as nearsightedness. Other people wear them to try to improve astigmatism.

Some people strongly feel that pinhole glasses work for these conditions, but the evidence is lacking.

“Eye doctors, both ophthalmologists and optometrists, for many decades have used pinhole glasses clinically to help determine certain things with a patient’s eyes in clinical practice,” said Dr. Larry Patterson, a practicing ophthalmologist in Crossville, Tennessee. “And yes, anytime someone wears pinhole glasses who is a little nearsighted, farsighted, or has astigmatism, [they] will see clearer [with the glasses on].”

Keep reading to find out what we know about pinhole glasses.

Myopia affects nearly 30 percent of people in the United States, estimates the American Optometric Association. People who have myopia have difficulty seeing clearly because of the shape of their eyes.

Pinhole glasses aren’t functional enough for everyday use if you’re nearsighted. Even though they help you focus on an object in front of you, they also block part of what you’re looking at. You can’t wear pinhole glasses while you’re driving or operating machinery.

Patterson, who’s also the chief medical editor of Ophthalmology Management, cites the lack of credible evidence to support the use of pinhole glasses outside of a clinical setting. “There are many disadvantages, including… reduction in peripheral vision,” he said.

Pinhole glasses could improve your vision, but only temporarily. Putting on pinhole glasses can restrict the amount of light that enters your pupils. This reduces the field of what doctors call the “blur circle” on the back of your retina. This gives your vision extra clarity when you have the glasses on.

Some people think that wearing pinhole glasses for a set amount of time each day can improve your overall vision over time, especially if you’re nearsighted or farsighted. There’s no conclusive evidence or clinical trials that support this belief, though.

Pinhole glasses may help people who have astigmatism to see better, but only when they’re wearing them.

Astigmatism keeps the rays of light that your eyes take in from meeting at a common focus. Pinhole glasses reduce the amount of light your eyes take in. But pinhole glasses also restrict your vision by blocking part of the image in front of you.

They also can’t reverse astigmatism. Your vision will go back to what it was when you take the glasses off.

If you’re concerned about myopia, the most effective way to improve your vision is to wear prescription glasses or contact lenses. These vision aids can ensure your safety and ability to enjoy everyday activities.

For some people, laser surgery is an option for improving eyesight. One option is LASIK surgery. It removes tissue from the inner layers of your cornea to reshape your eye.

Another option is PRK laser surgery. It removes some of the tissue on the outside of the cornea. People who have extremely limited eyesight are usually more suited for PRK laser surgery.

Both types of surgery have widely varying success rates, depending on who performs the surgery and individual risk factors.

Orthokeratology is another treatment for limited eyesight. This treatment involves wearing a series of shaped contact lenses designed to reshape your eye so you can see better.

If your nearsightedness gets worse because of stress, a muscle that controls how your eye focuses might be having spasms when you’re feeling pressured. Being proactive to reduce stress and talking to a doctor about possible solutions can help this kind of myopia.

Pinhole glasses are advertised as a way to decrease eyestrain. But a small 2017 study found that pinhole glasses may actually increase eyestrain significantly, especially if you try to read while you wear them. More studies are needed to see how pinhole glasses affect eyestrain.

If you experience glare from working in front of a screen all day, you may think about using pinhole glasses to reduce glare. But trying to work, read, or type while wearing the glasses could be uncomfortable and give you a headache.

Eye doctors sometimes use pinhole glasses as a diagnostic tool. By asking you to wear the glasses and talk about what you’re seeing, doctors can sometimes determine whether you’re having pain and other symptoms because of an infection or because of damage to your vision.

You can try pinhole glasses at home using materials you probably already have. Here’s what you need:

  • an old pair of glasses with lenses removed
  • aluminum foil
  • sewing needle

Simply cover the empty frames in aluminum foil. Then make a small hole in each foil lens. Use a ruler to make sure the two holes line up. Don’t put a hole through the foil when you have the glasses on.

Eye doctors are skeptical about using pinhole glasses to exercise your eyes. Patterson is among them.

“There are one or two very unusual conditions that can be sometimes helped with eye exercises. But this has nothing to do with routine eye care,” he said. “There is no credible evidence anywhere that suggests people can reduce their nearsightedness or farsightedness with exercises.”

In other words, the exercises that companies selling pinhole glasses advocate can’t cure or permanently improve eyesight for adults or children.

Never use pinhole glasses to look at the sun during a solar eclipse. You can make your own pinhole projector, though. It uses the same concept of focusing your eyes by blocking out stray light to safely view a solar eclipse.

Here’s how you make one:

  1. Cut a small hole at the end of a shoebox. The hole should be about 1 inch across and near the edge of the shoebox.
  2. Next, tape a piece of aluminum foil over the hole. Use a needle to make a small hole in the foil once it’s well-secured to the box.
  3. Cut a white piece of paper so that it fits easily at the other end of the shoebox. Tape it to the inside end of the shoebox. Keep in mind that the light coming from your aluminum-foil hole will need to hit that white paper so you can see the sun.
  4. On one side of the shoebox, create a hole that’s large enough for you to peer through with one of your eyes. This is your viewing hole.
  5. Replace the cover of the shoebox.

When it’s time to view an eclipse, stand with your back to the sun and lift the shoebox up so the aluminum foil faces where the sun is. Light will come through the hole and project an image onto the white “screen” of paper at the other end of the box.

By viewing that image through your pinhole projector, you can safely watch the whole eclipse without danger of burning your retina.

Pinhole glasses can be used as a clinical device to diagnose certain eye conditions. They can also be a fun accessory to wear around your house with the added benefit of bringing things into sharper focus.

But pinhole glasses block so much of your field of vision that they shouldn’t be worn for any activity that requires your eyesight. That includes housework and driving. They also don’t protect your eyes from the sun’s rays.

While companies sell pinhole glasses as a treatment for nearsightedness, doctors agree that there’s not medical evidence to suggest they’re effective for this use.