What Are Cataracts? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Cataracts are a clouding of the lens of your eye, resulting in changes to your vision. A cataract can develop in one eye at a time or both eyes simultaneously.

The lens of your eye consists of normally clear tissue that focuses light onto your retina, the layer of nerve cells lining the back wall of the inside of the eye. In your retina, light is converted to nerve signals that communicate information to your brain. (1,2)

While cataracts are considered a disorder and often benefit from treatment, they’re also a common and even normal part of aging. By age 80, more than one-half of all people in the United States will develop at least one cataract. (2)

While most cataracts are related to aging, there are also certain types that can develop during childhood or due to surgery, trauma, use of certain drugs, or other health problems.

Cataracts tend to grow progressively worse, causing vision impairment that may interfere with your daily activities. It’s important to talk to your doctor about any changes in your vision, and what options may be available for treating them. (2)

The most common initial symptom of a cataract is a small area of blurred vision. Over time, this area of blurred vision is likely to grow as your lens becomes more clouded. Eventually, you may get the sense that your overall vision is dull or blurry.

Along with vision that gets progressively blurrier, you may also experience color changes in your lens that cause everything you look at to take on a yellowish or brownish cast.

Eventually you may have trouble distinguishing colors, particularly shades of blue and purple, as well as performing tasks that require distinguishing colors, including reading.

Other than cloudy vision and color changes, symptoms of cataracts may include:

• Poor night vision
• Sensitivity to lamps, headlights, or sunlight
• Halos around lights
• Double vision
• Frequent changes to your glasses or contacts prescription (2,3)

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It’s a good idea to schedule an eye exam if you notice any changes in your vision over time. If you suddenly develop a change in your vision, see an eye doctor right away.

Learn More About Signs and Symptoms of Cataracts

The lens of your eye consists mostly of protein and water. The lens is located behind your pupil and iris (the black and colored areas of your eye), which are covered by your cornea (the clear outer layer of your eye).

The proteins in your lens are arranged in a way that keeps the lens clear. But because of normal changes that occur with age, these proteins can begin to clump together, resulting in cloudy areas of vision.

Over time, these protein clumps can grow larger, affecting a greater area of vision. (2)

A number of factors can increase your risk of developing cataracts, including:

• Older age
• Family history of cataracts
• Greater exposure to sunlight
• Living at a higher altitude
• Diabetes
• High blood pressure
• History of eye injury, inflammation, or surgery
• Radiation treatments on your upper body
• Smoking
• Drinking alcohol in excess
• Long-term use of corticosteroid drugs (1,3,4)

While most cataracts are related to aging, some people are born with cataracts or develop them during childhood. These are known as congenital cataracts.

Sometimes congenital cataracts have genetic causes, or they may be due to trauma or infection in the uterus. Conditions that can cause them include:

• Myotonic dystrophy, a type of muscular dystrophy
• Galactosemia, a rare metabolic disorder
• Neurofibromatosis type 2, a disorder in which tumors grow on nerves
• Rubella, sometimes called German measles
• Toxoplasmosis, a parasitic infection
• Cytomegalovirus, a viral infection
• Syphilis
• Herpes simplex virus

Congenital cataracts don’t always affect your vision, but if they do, they’re usually treated with surgery soon after they’re diagnosed. (3,4)

Cataracts are usually diagnosed by an eye doctor — an optometrist or ophthalmologist — using a variety of eye and vision tests.

You may need a dilated eye exam, in which drops are placed in your eyes to make your pupils widen so the doctor can see into the interiors of your eyes more easily. (2)

Tests that may help your eye doctor diagnose cataracts include:

Visual Acuity Test In this common test, you’re asked to read a series of letters from a chart.

Slit Lamp Exam In the basic version of this test, an eye doctor uses a special microscope to view structures in the front of your eye in detail.

Retinal Exam For this test, your eyes must be dilated, and your eye doctor uses a slit lamp or another device to view the backs of your eyes. (3)

Learn More About Diagnosing Cataracts: Tests and Screenings, Early Diagnosis, and Your Doctors

Prognosis of Cataracts

Age-related cataracts tend to develop slowly, sometimes taking years for noticeable vision changes to occur. There’s no way for doctors to predict how quickly your cataracts will develop or progress.

There are steps you can take that may slow the progression of your cataracts, including wearing glasses or sunglasses that block the sun’s ultraviolet (UV) rays. (1)

Cataracts don’t get better or go away on their own. While many people are able to take steps to adapt to living with cataracts, the only treatment that actually improves your vision is surgery. (2)

Once cataracts develop, the vision changes they cause will be permanent unless you get surgery to correct them. (2)

Most people develop cataracts that are age-related, caused by eye changes that start around age 40. But it may take many years for this process to cause noticeable changes to your vision.

By age 60, most people have some clouding in the lenses of their eyes. But vision problems may not occur because of this clouding until years later. (1)

The decision to have surgery for cataracts is usually based on how much your symptoms affect your daily activities and quality of life. How long it takes for cataracts to develop to this point varies widely between individuals. (3)

Types of Cataracts, Based on Cause and Location

Cataracts can be broadly divided into four groups according to their causes:

• Age-Related Cataracts This group accounts for the large majority of cataracts.
• Congenital Cataracts Cataracts in babies and children can be caused by a number of different factors.
• Secondary Cataracts In adults, cataracts can be caused by diseases like diabetes, or by drugs such as corticosteroids.
• Traumatic Cataracts An injury to one or both eyes may result in cataracts. This can happen soon after the injury or several years later. (4)

Cataracts can also be categorized by the area of the lens they affect. There are three types of cataract locations:

• Nuclear Cataracts This type of cataract affects the center of your lens. It tends to cause yellowing and clouding of the area.
• Cortical Cataracts This type of cataract affects the edges of your lens. It tends to cause white marks and streaks that gradually extend to the center of your lens.
• Posterior Subcapsular Cataracts This type of cataract affects the back of your lens. It tends to cause an initially small opaque area in the path of your vision, and often progresses faster than other types of cataracts. (3)

Surgery to replace the lens in your eye with an artificial lens is the only way to reverse cataracts. But it’s rarely necessary to have surgery immediately after your diagnosis.

The decision to have surgery depends on your general health and how much your cataracts are interfering with your daily life. If you are still able to drive or use public transportation, read, and perform the tasks you need to do in your home or workplace, you may decide to wait to have surgery.

Once you decide to go ahead with surgery, you should discuss what to expect with your doctor so you know how long you’ll likely be at the hospital (an overnight stay often isn’t necessary), what kind of symptoms are normal after surgery, and what kind of help or care from others you may need afterward.

Delaying surgery for cataracts generally doesn’t affect how well your vision recovers, since the procedure involves replacing the lens in your eye with a new one. (3)

Medication Options

There are currently no medications that directly slow or reverse the development of cataracts.

If you have an underlying health condition that may be contributing to cataracts, such as diabetes or high blood pressure, it’s important to take any medications prescribed and follow your treatment plan. (3)

Alternative and Complementary Therapies

There are steps you can take to help slow the development of cataracts and adapt to living with cataracts if they do appear.

Protecting your eyes from the sun’s harmful ultraviolet (UV) rays may slow the progression of cataracts. You can do this by wearing sunglasses or clear glasses that block UV light. (1)

To help adapt to vision changes caused by cataracts, you can do the following:

• Make sure your glasses or contacts prescription is up-to-date
• Wear anti-glare sunglasses
• Use brighter lights for activities as needed
• Use magnifying devices to read or perform other tasks (2)

Learn More About Treatment for Cataracts: Complementary Therapies, Surgery Options, and More

Prevention of Cataracts

No one step or approach has been proven to prevent cataracts, but a number of lifestyle measures may help to prevent them or slow their development.

Potentially helpful steps include the following:

• Wear sunglasses or glasses that block ultraviolet (UV) light
• Manage diabetes or high blood pressure if you have it
• Quit smoking if you smoke
• Drinking only moderate amounts of alcohol
• Follow a healthy diet that’s high in fruits and vegetables

Most of these actions have the additional advantage of conferring health benefits beyond good eye health.

One approach that has not been shown to protect against cataracts is taking dietary supplements, and certain antioxidant supplements have even been shown to have harmful effects. (3)

Learn More About Preventing Cataracts

Worldwide, cataracts are the leading cause of blindness, and an estimated 20.5 million Americans over age 40 have the condition. (5)

In some people who have surgery for cataracts — which replaces the eye’s natural lens with an artificial lens — natural lens cells grow back over time, which can lead to new cataracts (known as secondary cataracts). In fact, as many as 50 percent of people who undergo cataract surgery have natural lens cells behind their artificial lens 5 to 10 years later.

Secondary cataracts may be treated by laser eye surgery, but this surgery may damage the artificial lens. (6)

Congenital cataracts — which are present at birth or develop during childhood — are the most common cause of lifelong vision loss in children. Even with early surgery and other treatments, many children with congenital cataracts end up with vision problems such as deprivation amblyopia, nystagmus, strabismus, or glaucoma. (7)

Your risk of developing cataracts increases as you get older, starting around age 40.

Cataracts are more likely to affect women than men. Women account for 61 percent of cataract cases, with men claiming the remaining 39 percent. The fact that women live longer than men accounts for some of this difference.

The risk of cataracts is not the same for all racial and ethnic groups in the United States. Starting around age 70, white Americans are at higher risk than any other group, while Black Americans have the lowest risk. This gap grows wider with increasing age.

The incidence of cataracts is expected to rise. By 2050, the number of people with cataracts in the United States is projected to be more than double current trends and affect over 50 million people. (8)

While the incidence of cataracts has risen around the world, in part because people are living longer, many countries have seen a drop in blindness from cataracts.

The largest drops in age-standardized blindness due to cataracts — because of improved screening and treatment — between 1990 and 2010 were seen in East Asia, tropical Latin America, and Western Europe. The highest rate of blindness due to cataracts was seen in sub-Saharan Africa, where it’s estimated to affect 6 percent of adults over age 50. (9)

There is ongoing research related to cataracts in many different areas, including genetic causes, ways to improve the success of surgery, and potential nonsurgical treatments. By studying the processes that cause lens cells to become cloudy, it may be possible to develop a topical medication — an eye drop — that can stop or reverse cataract formation. (6)

Cataracts are not known to result from, or contribute to, other types of eye disease. But many of the risk factors for cataracts — such as older age, smoking, and exposure to ultraviolet (UV) light — can also lead to other forms of eye disease or vision loss.

Common eye disorders that may overlap with cataracts include the following:

Age-Related Macular Degeneration (AMD) This eye disorder affects the macula, the central part of the retina. When the macula thins, it can cause a gradual blurring of central vision, which can interfere with tasks like reading and driving.

Diabetic Retinopathy In people with diabetes, elevated blood glucose can damage the blood vessels in the eye’s retina, causing vision loss over time. This process tends to affect both eyes, and may be slowed or reversed through good diabetes control.

Glaucoma This group of disorders is typically defined by increased pressure inside the eye, which can eventually damage the optic nerve and lead to vision loss. Early treatment of glaucoma may help prevent vision loss and blindness. (5)

Different racial and ethnic groups in the United States experience different rates of cataracts, with white people having the highest risk. By age 75, half of white Americans will have a cataract.

The risk of cataracts starts out close to even for all racial and ethnic groups, rising from below 5 percent in the 40- to 49-year-old age group to about 10 percent in the 55 to 59 age group and just over 20 percent in the 65 to 69 age group.

But by the time people reach the 70 to 74 age group, white people have a significantly higher cataract risk, with Black Americans having the lowest risk, and other groups falling in between. The gaps between these groups grow wider with age. (8)

Black Americans and Cataracts

Judging by the available data, Black Americans have the lowest risk of cataracts out of any racial or ethnic group.

Just 53 percent of Black Americans have cataracts by age 80, compared with 70 percent of white Americans, according to the National Eye Institute. (8)

Hispanic Americans and Cataracts

The risk of cataracts is lower in Hispanic Americans than white Americans, with 61 percent developing them by age 80, compared with 70 percent of the white population.

While white people are still expected to account for most cataracts in the future, the most dramatic rise is projected for Hispanic Americans. The number of cases in this group is expected to grow from 1.8 million in 2010 to 9.5 million in 2050. (8)

American Academy of Ophthalmology

See what a cataract looks like, what looking through a cataract is like, and much more on the website of the American Academy of Ophthalmology.

American Optometric Association

Learn more about cataracts and other common eye conditions on the website of the American Optometric Association.

National Eye Institute

Get the latest updates on cataract research supported by the National Eye Institute.

National Institute on Aging

Learn how aging can affect your eyes and vision, when to see a doctor, and how to live better with low vision.