what are bifocals used for

Bifocals are a type of eyeglasses that feature two different optical powers in one lens. The top part of a bifocal lens corrects distance vision, while the bottom part corrects near vision. Bifocals are used for people who are both nearsighted and farsighted, and it is common for people over the age of 40 to begin to notice a change in their vision and require the need for bifocals. Presbyopia is the most common reason people need bifocals. Symptoms of presbyopia include the need to hold reading material at a distance to see clearly, eye strain, frequent headaches, reduced reading vision in low light, blurry vision when looking at small print, and trouble focusing on a computer screen. Bifocals help people with presbyopia see near and far objects clearly without the need for separate reading glasses.