HOW CATARACTS CAN AFFECT YOUR VISION

How a cataract affects your vision

Clear vision, as shown on the left, becomes blurry as a cataract forms, as shown on the right.

Symptoms

Cataract symptoms 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.

At first, the cloudiness in your vision caused by a cataract may affect only a small part of the eye's lens. You may not notice any vision loss. As the cataract grows larger, it clouds more of your lens. More cloudiness changes the light that passes through the lens. This can lead to more noticeable symptoms.

When to see a doctor

Make an appointment for an eye exam if you notice any changes in your vision. If you develop sudden vision changes, such as double vision or flashes of light, sudden eye pain, or sudden headache, see your healthcare team member right away.

Causes

Most cataracts develop when aging or injury changes the tissue that makes up your eye's lens. Proteins and fibers in the lens begin to break down, causing vision to become hazy or cloudy.

Some inherited genetic disorders that cause other health problems can increase your risk of cataracts. Cataracts can also be caused by other eye conditions, past eye surgery, or medical conditions such as diabetes. Long-term use of steroid medications can also cause cataracts to develop.

How a cataract forms

A cataract is a clouded 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.

As you age, the lenses in your eyes become less flexible, less transparent and thicker. Aging and medical conditions can cause proteins and fibers within the lenses to break down and clump together. This is what causes the cloudiness in the lenses.

As the cataract continues to develop, the cloudiness 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 usually develop in both eyes, but not always at the same rate. The cataract in one eye may be worse than the other, causing a difference in vision between eyes.

Types of cataracts

Types of cataracts include:

• Cataracts affecting the center of the lens (nuclear cataracts). A nuclear cataract may at first cause far objects to look blurry while near objects remain clear. A nuclear cataract may even temporarily improve your reading vision for a while. But with time, the lens turns more densely yellow or brown and clouds your vision. It may become difficult to distinguish between colors.
• Cataracts that affect the edges of the lens (cortical cataracts). A cortical cataract begins as wedge-shaped, whitish 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 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. It tends to reduce your vision in bright light and cause 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 also may be due to certain conditions, such as myotonic dystrophy, galactosemia, neurofibromatosis type 2 or rubella. Congenital cataracts don't always affect vision. If they do, they're usually removed soon after detection.

Risk factors

Factors that increase your risk of cataracts include:

• Increasing age.
• Diabetes.
• Excessive exposure to sunlight.
• Smoking.
• Obesity.
• Family history of cataracts.
• Previous eye injury or inflammation.
• Previous eye surgery.
• Prolonged use of corticosteroid medications.
• Excessive alcohol consumption.

Prevention

No studies have proved how to prevent cataracts or slow their progression. But healthcare providers think several strategies may be helpful, including:

• Regular eye examinations. Eye examinations can help detect cataracts and other eye problems at their earliest stages. Ask your healthcare team how often you should have an eye examination.
• Quit smoking. Ask your healthcare team member 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 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.