In young people, the lens is soft and flexible and able to change shape to switch one ... glasses and reading something — perhaps on your phone or in a magazine. Choose the lowest reading power ...

Reading glass power is measured in units called diopters. The lowest strength is usually 1.00 diopters. Glasses go up in strength by factors of .25 (1.50, 1.75, 2.00).

Reading glasses are often one-size-fits-all and may not fit your face properly. “Poor fit can cause discomfort and improper lens positioning, reducing effectiveness,” says Dr. Heyman.

Reading glasses are meant to magnify and are rated by their diopter (power). Typically, powers range from +1.00 to +3.00. The higher the number, the stronger the magnification.

One day I could read the tiny instructions ... “If you already know what power reading glasses you use or are just replacing a pair, purchasing reading glasses online is a very simple process ...

In the U.S., the U.K. and many other European countries, reading glasses are readily available over-the-counter at most drugstores. That's not the case elsewhere.

The maker of One Power Readers claims these multi-power glasses will adjust to different strengths depending on your needs. Read the small print, computer screens without ever changing your glasses.

You may need different pairs of readers for different activities. “If you’re wearing the reading glasses primarily when using ...