Cataracts

  • Medical Author:
    Andrew A. Dahl, MD, FACS

    Andrew A. Dahl, MD, is a board-certified ophthalmologist. Dr. Dahl's educational background includes a BA with Honors and Distinction from Wesleyan University, Middletown, CT, and an MD from Cornell University, where he was selected for Alpha Omega Alpha, the national medical honor society. He had an internal medical internship at the New York Hospital/Cornell Medical Center.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Cataracts Pictures Slideshow

Quick GuideCataracts Causes, Symptoms, Vision Tests and Surgery

Cataracts Causes, Symptoms, Vision Tests and Surgery

Facts about cataracts

  • A cataract is a clouding of the lens of the eye.
  • Cataracts are extremely common, and most cataracts are a result of the aging process.
  • Although many cataracts are not significant enough to require treatment, surgical removal of cataracts is usually safe and effective, resulting in improvement of vision.
  • Cataract surgery should be performed when the visual loss from the cataract significantly impacts the lifestyle of the individual patient.

What is a cataract?

A cataract is an eye disease in which the clear lens of the eye becomes cloudy or opaque, causing a decrease in vision. Although the word cataract to describe this condition has been part of the English language since only the 15th century, the eye disease has been recognized and surgically treated since ancient times.

Eyeball Illustration - Cataracts
Eyeball Illustration - Cataracts

The lens is a portion of the eye that is normally clear. It focuses rays of light entering the eye onto the retina, the light-sensitive tissue at the back of the eye. In order to get a clear image onto the retina, the portions of the eye in front of the retina, including the lens, must be clear and transparent. The light striking the retina initiates a chemical reaction within the retina. The chemical reaction, in turn, initiates an electrical response which is carried to the brain through the optic nerve. The brain then interprets what the eye sees.

In a normal eye, light passes through the transparent lens to the retina. The lens must be clear for the retina to receive a sharp image. If the lens is cloudy from a cataract, the image striking the retina will be blurry or distorted and the vision will be blurry. The extent of the visual disturbance is dependent upon the degree of cloudiness of the lens.

Most cataracts are related to aging. Cataracts are very common in older people. By age 80, more than half of all Americans either have some degree of cataract or have already undergone cataract surgery in one or both eyes. By age 95, this percentage increases to almost 100%. A cataract can occur in either or both eyes. Individuals with a cataract in one eye usually go on to develop a cataract in the other eye as well. A cataract is not contagious and cannot spread from one eye to the other or from person to person. Cataracts do not cause the eye to tear abnormally. They are neither painful nor make the eye itchy or red.

Although vision can be restored in most people with cataracts, age-related cataracts are still the most common cause of blindness in the world, primarily because many third-world nations lack appropriate and available surgical services.

As life span increases in the developed world due to modern technology and new methods of treatment of acute and chronic disease, the incidence of age-related cataracts will continue to increase.

Medically Reviewed by a Doctor on 8/12/2016

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