Over 140 million people in the U.S. wear eyeglasses, and over 30 million wear contact lenses. Glasses and contact lenses improve vision by adjusting the way the eyes bend and focus light. Ideally, light rays are refracted (bent) as they pass through the cornea so that they focus on the retina in the back of the eye. In a healthy eye, this means that objects can be seen clearly. However, many people’s corneas have a shallow or steep curvature which causes light rays to focus in front of or behind the retina. Objects may then appear blurry at certain distances or at all distances.
Glasses and contact lenses correct these refractive errors. Prescriptions are measured for each eye so patients can enjoy optimal vision clarity, usually 20/20. Eyewear may be used for certain activities, such as reading for farsighted (hyperopic) patients and driving or watching television for nearsighted (myopic) patients or may be worn at all times.