Around the age of 40, most people will develop presbyopia, a condition similar to farsightedness. The eyes gradually lose the ability to focus on close objects, particularly small print. Nearly everyone develops presbyopia at some point in their life, and it is an incurable condition.

Reading glasses magnify close objects and help improve near vision. Generally, people who have never needed vision correction with prescription eyeglasses will start out with reading glasses, rather than bifocals or progressive lenses.

Using a simple eye chart, reading glass wearers can determine the right magnification, or diopter strength, on their own. As presbyopia progresses, wearers will need an increased diopter strength every year or so. It is not also
uncommon for wearers to need more than one pair of reading glasses in different diopter strengths for different situations, such as lighting, fatigue and stress.