Cataract
A cataract is a dense, cloudy area that forms in the lens of the eye. A cataract begins when proteins in the eye form clumps that prevent the lens from sending clear images to the retina. The retina works by converting the light that comes through the lens into signals. It sends the signals to the optic nerve, which carries them to the brain.
It develops slowly and eventually interferes with your vision. You might end up with cataracts in both eyes, but they usually don’t form at the same time. Cataracts are common in older people.
Symptoms
Signs and symptoms of cataracts include:
- Clouded, blurred or dim vision
- Increasing difficulty with vision at night
- Sensitivity to light and glare
- Need for brighter light for reading and other activities
- Seeing "halos" around lights
- Frequent changes in eyeglass or contact lens prescription
- Fading or yellowing of colors
- Double vision in a single eye
How a cataract forms
A cataract is a cloudy lens. The lens is positioned behind the colored part of your eye (iris). The lens focuses light that passes into your eye, producing clear, sharp images on the retina — the light-sensitive membrane in the eye that functions like the film in a camera.
As you age, the lenses in your eyes become less flexible, less transparent and thicker. Age-related and other medical conditions cause proteins and fibers within the lenses to break down and clump together, clouding the lenses.
As the cataract continues to develop, the clouding becomes denser. A cataract scatters and blocks the light as it passes through the lens, preventing a sharply defined image from reaching your retina. As a result, your vision becomes blurred.
Cataracts generally develop in both eyes, but not always at the same rate. The cataract in one eye may be more advanced than the other, causing a difference in vision between eyes.
Risk factors
- Increasing age
- Diabetes
- Excessive exposure to sunlight
- Smoking
- Obesity
- High blood pressure
- Previous eye injury or inflammation
- Previous eye surgery
- Prolonged use of corticosteroid medications
- Drinking excessive amounts of alcohol
Prevention
No studies have proved how to prevent cataracts or slow the progression of cataracts. But doctors think several strategies may be helpful, including:
- Have regular eye examinations. Eye examinations can help detect cataracts and other eye problems at their earliest stages. Ask your doctor how often you should have an eye examination.
- Quit smoking. Ask your doctor for suggestions about how to stop smoking. Medications, counseling and other strategies are available to help you.
- Manage other health problems. Follow your treatment plan if you have diabetes or other medical conditions that can increase your risk of cataracts.
- Wear sunglasses. Ultraviolet light from the sun may contribute to the development of cataracts. Wear sunglasses that block ultraviolet B (UVB) rays when you're outdoors.
- Reduce alcohol use. Excessive alcohol use can increase the risk of cataracts.
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