Eyeglasses become necessary when a person’s vision isn’t up to par because one or more conditions are present. Nearsightedness, for example, causes blurry vision of distant objects. Farsightedness makes objects near to you appear blurry, and may cause eye strain or headaches. And astigmatism refers to an uneven curvature of the clear covering of the eye, called the cornea (KOR-nee-uh), causing blurriness of vertical, horizontal or diagonal lines.

Glasses can usually correct these visual problems, and your doctor will prescribe the lenses that will help bring your vision into focus. Frames for the lenses can be purchased in some eye doctors’ offices, or you can go to a store that sells glasses. It can take anywhere from an hour to several weeks for your prescription to be filled. The professionals dispensing the glasses will fit them to your face to ensure comfort, and will instruct you on their care.