A cataract is a clouding of the lens of the eye that can impair vision. More than half of all Americans age 65 and older have cataracts in their eyes. See image below
What Causes Cataracts?
The eye functions much like a camera. Light rays enter through the front of the eye, passing through the cornea, the pupil, and the aqueous humor -- transparent fluid in the front of the eye -- onto the lens. The lens then bends light rays to focus objects onto the retina in the back of the eye. From there, the retina, the optic nerve, and the brain process the images and form vision.
Cataracts occur when there is a buildup of protein in the lens that makes it cloudy. This prevents light from passing through a normally clear lens, causing some loss of vision. A cataract is a lens that has become clouded.
Types of cataracts include:
- Age-related cataracts. As the name suggests, this type of cataract develops as a result of aging.
- Congenital cataracts. Babies are sometimes born with cataracts as a result of an infection they had before they were born, or they may develop during childhood.
- Secondary cataracts. These may develop as a result of other diseases, like diabetes, or long-term exposure to toxic substances, certain medications (such as corticosteroids or diuretics), ultraviolet light, and radiation.
- Traumatic cataracts. These can form after injury to the eye.
What Are the Symptoms of Cataracts?
Cataracts often form slowly and cause few symptoms. When symptoms are present, they can include:
- Vision that is cloudy, blurry, foggy or filmy.
- Sudden nearsightedness.
- Changes in the way you see color, especially yellow.
- Problems driving at night because oncoming headlights are distracting.
- Problems with glare.
- Double vision.
- Sudden temporary improvement in close-up vision.
How Are Cataracts Diagnosed?
A series of tests can be performed by your eye doctor. An eye exam will be given to test how well you can see (remember to bring your glasses or wear your contacts to the appointment). Your doctor may also dilate your pupils in order to examine the condition of the lens and other parts of the eye.