Just like your joints and other body parts, your eyes can be affected by aging. As you get older (around 40), the natural inner lens in your eye loses some of its flexibility. When you're young, they can focus more easily from near to far. As your eyes become less flexible, so does your ability to see closely. Presbyopia is a condition that may make you wonder if you need reading glasses.

Here are some signs that you may need reading glasses:

Books and other reading materials appear blurred up close. To read them, you have to hold them further.

You'll have problems reading smaller fonts in dim light.

Your eyes hurt when you try to read or do other close work.

When you try to read, you get a headache.

How do you choose your strength?

Look for the tag number on any cheap "reader" you choose to try at a local optician or online store such as Lensmart. Diopter is a unit used to measure the power of a reading glass. Usually, 1.00 diopter is the lowest strength.

To determine which one works best, try several. Try wearing reading glasses and holding a book or magazine 14 to 16 inches from your face to see if the print is easier to see. One pair is used for close reading and the other pair is used for medium-distance reading, such as a computer screen, which may require two different intensities.

Keep in mind that these glasses may not fit you as well as prescription glasses. They can't be adjusted if you need a different intensity in each eye, and they won't correct astigmatism, a problem that often leads to blurred vision. Also, your vision may change as you age. After a year or two, you may need to invest in a stronger pair of reading glasses.