|
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.
Patients with myopia, or nearsightedness, have steep curvature in one or both corneas; they can focus on nearby objects, but distant objects appear blurry. For hyperopic or farsighted patients, shallow corneal curvature causes nearby objects to appear blurry while objects in the distance are clear. Astigmatism causes objects that are close or at a distance to appear blurry or doubled. Most people have some degree of astigmatism, which often occurs in combination with myopia or hyperopia.
Glasses and contact lenses correct for 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 hyperopic patients and driving or watching television for myopic patients, or may be worn at all times.
Regular eye exams test for the development and progression of refractive errors and help your ophthalmologist provide a proper prescription if eyeglasses or contact lenses are needed. Exams are also an invaluable tool in the early detection of eye disease.
|
