How Do Reading Glasses Work?

Reading glasses magnify the information coming into your eyes, making it easier for the internal lenses in your eyes to focus on nearby objects. They’re not meant to be worn all the time. You might tuck your glasses case into your purse or choose a simple cord so you can wear them around your neck.

Some people even need two pairs of reading glasses: one to read very close print, like books, and another for mid-distance reading, like a computer screen. 

How Do Reading Glasses Work? Do They Magnify?

A common misconception about reading glasses is that they magnify small print. Actually, they make it easier to read small print by providing the correct diopter strength which usually begins at +0.75 all the way up to +4.00 (more on that later). As typically worn, that will crystalize near focus for reading and other close work tasks so that your eyes have an easier time to focus. Reading glasses will not discernibly enlarge the size of text or near objects compared with when they are removed, though the crystalizing effect can often feel that way.

What's Diopters?

Reading lenses are rated in diopters, a formula opticians use. Manufacturers of reading glasses often contribute to consumer confusion by referring to magnification power and diopter strength interchangeably. They are not the same thing. But it’s easier for people to understand magnification than the science of lenses. A slightly more technical explanation. With every power option, or “diopter”, there is a sweet spot range where close vision is brought into sharp focus. 

This changes from person to person. If the diopter is too weak for your individual needs, you will need to move the material farther away from your face to see it clearly. If the diopter is too strong, that range of sweet spot will be closer than you prefer. 

The average person reads material between 14 - 18 inches away from their face. If you would like to restore a comfortable reading range that is within that, find a diopter that sharpens focus in this range. In contrast, if you are working at your desk and your computer monitor is 24 inches away, you will need a weaker power than you would for reading.

How Do Reading Glasses Work?

When Do You Need Reading Glasses?

As people get older, they need reading glasses to help them to read and improve their vision. Reading glasses can help compensate for diminished vision like presbyopia. This is a common age-related loss of the ability to concentrate on any kind of up-close object.

In fact, if you feel tired while reading for just a while, having some trouble while reading some small objects, or need to pull the objects little farther away from your face when you read, reading glasses will be a good way to help you to solve these problems.


  • Do you find yourself squinting and holding your reading material farther away?
  • Do you have a hard time reading in lower light conditions?
  • Are you around 40 years old and experience eye strain when reading?
  • Have you recently begun having trouble reading but your vision is still great at a distance, or you traditionally wear contact lenses to correct distance vision but notice your up-close reading is becoming more difficult?

Tips for Buying Reading Glasses

  • Schedule an Eye Exam

As long as it is not an emergency, the first thing you should do is call your local eye doctor and make an appointment for a comprehensive eye examination. You are most likely experiencing symptoms of what many jokingly call the "over 40 syndrome" or "short arm syndrome." This condition is officially called presbyopia by your eye doctor. However, blurry vision can sometimes be a sign of a serious eye problem or eye disease. To be safe, schedule an eye exam to make sure your eyes are in excellent health.

  • Consider Prescription Reading Glasses

One drawback to purchasing ready-made reading glasses is that they are essentially "one-size-fits-all" items. Most people do not have exactly the same prescription in both eyes, and almost everyone has at least a small amount of astigmatism correction in their prescriptions. Customize prescription reading glasses is the best choice.

  1. Powers in OTC readers are the same in each eye. You may need a different power for each of your eyes. Looking through readers of the wrong power can cause eye strain, making one eye work much harder than the other.
  2. OTC readers do not correct astigmatism; prescription readers do.1 Many people have a small amount of astigmatism. Uncorrected astigmatism can cause headaches, tired eyes, and vision that seems a little off.
  3. OTC readers are basically "one size fits all." Prescription reading glasses are made so that the optical center of the lens is lined up exactly at the center of the pupil. When the optical center is not lined up, you may end up looking through the side of the lens, which can cause eye strain and eye muscle imbalances.
  4. Prescription lenses are made optically perfect with no distortions, waves or bubbles in the lenses. If you examine a pair of OTC readers of low quality, the lenses may have some unwanted defects.
  5. OTC readers do not work for nearsighted people because such individuals usually require a "minus or negative" lens. OTC glasses only come in "plus or positive" powered lenses.
  • Consider OTC Readers

If your eyes are such that ready-made readers will work just fine, your eye doctor will let you know. If he or she decides that they are sufficient for you, ask him what power is recommended for your eyes. Be sure to discuss your occupation and the types of hobbies you enjoy, as the power your doctor recommends may depend on what type of work you do.

For example, the power prescribed for you if you spend eight hours a day on the computer will likely be different than one prescribed for you if you spend a lot of time reading or working with fine detail.


After understanding how reading glasses work, I believe you can find the right reading glasses for yourself. Prescription reading glasses are the best choice. Prescription reading glasses are meant to be worn for extended periods, and they are ideal for people with astigmatism, myopia, serious eye disorders or unequal prescription strength in each eye. Reading Glasses Don't Deteriorate Your Eyesight.