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How to Find Your Reading Glasses Strength

Many individuals who are nearing the age of 40 will experience presbyopia, which results in a decreased ability to focus on close-range objects. Luckily, reading glasses are a cheap and effective solution, and don't even require a doctor's prescription so they are easy to purchase online. It's just a matter of finding the proper strength for your eyes. While the lack of a prescription requirement makes the purchase of readers convenient, it can be a challenge to find what strength you need if you've never tried on reading glasses before.

What Do the Numbers Mean?

For those who've just recently started to experience presbyopia, the first thing they'll see when looking for reading glasses are a bunch of tags and labels that read similar to the numbers listed below.

  • +1.00
  • +1.50
  • +2.25
  • +3.00
  • +3.50
  • +4.00

The numbers above represent the corrective strength of eyeglass lenses. The units are known as "diopters" and are typically measured in increments of .25 diopters to differentiate stronger and weaker corrective powers. Someone who needs strong vision correction will likely need reading glasses with a strength around +3.00, while someone who needs only minor vision correction would likely wear reading glasses with a label of +1.25.

For most people new to needing readers, it's highly unlikely that they'll need a high powered lens. Presbyopia typically starts as a minor vision impediment and slowly increases as you age. While it's possible for people to need reading glasses with a strength of 3.50 - 4.00 diopters, it’s relatively rare.

Finding Your Lens Power Based on Age

Since presbyopia is affected by aging, the lens power needed for reading glasses can be roughly estimated based on your age. Use this guide as a starting point.

30-40 Years Old
45 Years Old
50 Years Old
60 Years Old
+2.50 - +3.00

How Will You Use Your Readers?

The lens power needed for reading glasses differs depending on purpose. The traditional reading distance is 14-16 inches, but it’s 18-20 inches for computer reading. Because the distances are not the same, the lens power will also be different. After calculating your lens strength for reading, reduce that by about half to find your correct power for reading a computer screen. This power might need to be adjusted based on the distance between the computer screen and your eyes.

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