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.
HOW A CATARACT FORMS
A cataract is a cloudy lens. The lens is positioned behind the colored part of the eye (iris). The lens focuses light that passes into the eye, producing clear, sharp images on the retina — the light-sensitive membrane in the eye that functions like the film in a camera.
As one ages, 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.
CAUSES/ RISK FACTORS
Factors that increase your risk of cataracts include:
- Increasing age
- Excessive exposure to sunlight
- High blood pressure
- Previous eye injury or inflammation
- Previous eye surgery
- Prolonged use of corticosteroid medications
- Excessive alcohol intake
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
TYPES OF CATARACTS
Cataract types include:
- Cataracts affecting the center of the lens (nuclear cataracts). A nuclear cataract may at first cause more nearsightedness or even a temporary improvement in your reading vision. But with time, the lens gradually turns more densely yellow and further clouds your vision. As the cataract slowly progresses, the lens may even turn brown. Advanced yellowing or browning of the lens can lead to difficulty distinguishing between shades of color.
- Cataracts that affect the edges of the lens (cortical cataracts). A cortical cataract begins as whitish, wedge-shaped opacities or streaks on the outer edge of the lens cortex. As it slowly progresses, the streaks extend to the center and interfere with light passing through the center of the lens.
- Cataracts that affect the back of the lens (posterior subcapsular cataracts). A posterior subcapsular cataract starts as a small, opaque area that usually forms near the back of the lens, right in the path of light. A posterior subcapsular cataract often interferes with your reading vision, reduces your vision in bright light, and causes glare or halos around lights at night. These types of cataracts tend to progress faster than other types do.
- Cataracts you’re born with (congenital cataracts). Some people are born with cataracts or develop them during childhood. These cataracts may be genetic, or associated with an intrauterine infection or trauma. These cataracts may also be due to certain conditions, such as myotonic dystrophy, galactosemia, neurofibromatosis type 2 or rubella. Congenital cataracts don’t always affect vision, but if they do, they’re usually removed soon after detection.
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.
- Choose a healthy diet that includes plenty of fruits and vegetables: Adding a variety of colorful fruits and vegetables to your diet ensures that you’re getting many vitamins and nutrients. Fruits and vegetables have many antioxidants, which help maintain the health of your eyes.
- Studies haven’t proved that antioxidants in pill form can prevent cataracts: But a large population study recently showed that a healthy diet rich in vitamins and minerals was associated with a reduced risk of developing cataracts. Fruits and vegetables have many proven health benefits and are a safe way to increase the amount of minerals and vitamins in your diet.
- Wear sunglasses: Ultraviolet light from the sun contributes to the development of cataracts. Wear sunglasses that block ultraviolet B (UVB) rays when you’re outdoors.
- Reduce alcohol intake: Excessive alcohol intake can increase the risk of cataracts.
Surgery is the only known treatment for cataract.
When your prescription glasses can no longer give you a clearer vision, the only effective treatment for cataract becomes surgery.