Cataract

What You Should Know

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

National Institutes of Health

National Eye Institute
2

The National Eye Institute (NEI) conducts and supports 

research that leads to sight-saving treatments and plays a 

key role in reducing visual impairment and blindness. NEI is 

part of the National Institutes of Health, an agency of the 

U.S. Department of Health and Human Services. 

For more information, contact—

National Eye Institute 

National Institutes of Health

2020 Vision Place

Bethesda, MD 20892–3655

Telephone: 301–496–5248

Email: 2020@nei.nih.gov

Website: www.nei.nih.gov
Contents

About Cataracts 1

Detection 6

Treatment 7

Current Research 13

What You Can Do 13

Additional Resources 16
4
1

About Cataracts

What is a cataract?

A cataract is a clouding of the lens in the eye that affects 

vision. Most cataracts are related to aging. Cataracts are very 

common in older people. By age 80, more than half of all 

Americans have either a cataract or have had cataract surgery.

A cataract can occur in either or both eyes. It cannot spread 

from one eye to the other.

What is the lens?

The lens is a clear part of the eye that helps to focus light, 

or an image, on the retina. The retina is the light-sensitive 

tissue at the back of the eye. (See diagram below.)
2

2

In a normal eye, light passes through the transparent lens 

to the retina. Once it reaches the retina, light is changed 

into nerve signals that are sent to the brain.

The lens must be clear for the retina to receive a sharp 

image. If the lens is cloudy from a cataract, the image you 

see will be blurred.

What causes cataracts?

The lens lies behind the iris and the pupil. It works much 

like a camera lens. It focuses light onto the retina at the 

back of the eye, where an image is recorded. The lens also 

adjusts the eye's focus, letting us see things clearly both up 

close and far away. The lens is made of mostly water and 

protein. The protein is arranged in a precise way that keeps 

the lens clear and lets light pass through it.

But as we age, some of the protein may clump together 

and start to cloud a small area of the lens. This is a cataract. 

Over time, the cataract may grow larger and cloud more of 

the lens, making it harder to see.

Smoking and diabetes contribute to the development of 

cataract. Or, it may be that the protein in the lens just 

changes from the wear and tear it takes over the years.

How do cataracts affect vision?

Age-related cataracts can affect vision in two ways:

1. Clumps of protein reduce the sharpness of the image 

reaching the retina.
3

 The lens consists mostly of water and protein. When the 

 protein clumps up, it clouds the lens and reduces the 

light that reaches the retina. The clouding may become 

severe enough to cause blurred vision. Most age-related 

cataracts develop from protein clumpings.

 When a cataract is small, the cloudiness affects only a 

small part of the lens. You may not notice any changes 

in your vision. Cataracts tend to "grow" slowly, so vision 

gets worse gradually. Over time, the cloudy area in the 

lens may get larger, and the cataract may increase in 

size. Seeing may become more difficult. Your vision may 

get duller or blurrier.

2. The clear lens slowly changes to a yellowish/brownish 

color, adding a brownish tint to vision.

 As the clear lens slowly colors with age, your vision 

gradually may acquire a brownish shade. At first, the 

amount of tinting may be small and may not cause a 

vision problem. Over time, the cataract usually increases 

in size. This gradual change in the amount of tinting 

does not affect the sharpness of the image transmitted 

to the retina.

 If you have advanced lens discoloration, you may not be 

able to identify blues and purples. You may be wearing 

what you believe to be a pair of black socks, only to find 

out from friends that you are wearing purple socks.

About Cataracts
4

4

When are you most likely to have a cataract?

The term "age-related" is a little misleading. You don't 

have to be a senior citizen to get this type of cataract. 

In fact, people can have an age-related cataract in their 

40s and 50s. But during middle age, most cataracts are 

small and do not affect vision. It is after age 60 that most 

cataracts cause problems with a person's vision.

Who is at risk for cataract?

The risk of cataract increases as you get older. Other risk 

factors for cataract include:

• Certain diseases (for example, diabetes).

• Personal behavior (smoking, alcohol use).

• The environment (prolonged exposure to ultraviolet 

sunlight).

What are the symptoms of a cataract?

The most common symptoms of a cataract are:

• Cloudy or blurry vision.

• Colors seem faded.

• Glare. Headlights, lamps, or sunlight may appear too 

bright. A halo may appear around lights.

• Poor night vision.

• Double vision or multiple images in one eye. 

(This symptom may clear as the cataract gets larger.)
5

Normal vision The same scene as viewed by 

a person with cataract

• Frequent prescription changes in your eyeglasses or 

contact lenses.

These symptoms also can be a sign of other eye problems. 

If you have any of these symptoms, check with your eye 

care professional.

Are there different types of cataract?

Yes. Although most cataracts are related to aging, there 

are other types of cataract:

• Secondary cataract. Cataracts can form after surgery for 

other eye problems, such as glaucoma. Cataracts also 

can develop in people who have other health problems, 

such as diabetes. Cataracts are sometimes linked to 

steroid use.

About Cataracts
6

6

• Traumatic cataract. Cataracts can develop after an eye 

injury, sometimes years later.

• Congenital cataract. Some babies are born with 

cataracts or develop them in childhood, often in both 

eyes. These cataracts may be so small that they do not 

affect vision. If they do, the lenses may need to be 

removed.

• Radiation cataract. Cataracts can develop after exposure 

to some types of radiation.

How is a cataract detected?

Cataract is detected through a comprehensive eye exam 

that includes:

• Visual acuity test. This eye chart test measures how well 

you see at various distances.

• Dilated eye exam. Drops are placed in your eyes to 

widen, or dilate, the pupils. Your eye care professional 

uses a special magnifying lens to examine your retina 

and optic nerve for signs of damage and other eye 

problems. After the exam, your close-up vision may 

remain blurred for several hours.

• Tonometry. An instrument measures the pressure inside 

the eye. Numbing drops may be applied to your eye for 

this test.

Your eye care professional also may do other tests to learn 

more about the structure and health of your eye.
7

Treatment

How is a cataract treated?

The symptoms of early cataract may be improved with 

new eyeglasses, brighter lighting, anti-glare sunglasses, or 

magnifying lenses. If these measures do not help, surgery is 

the only effective treatment. Surgery involves removing the 

cloudy lens and replacing it with an artificial lens.

A cataract needs to be removed only when vision loss 

interferes with your everyday activities, such as driving, 

reading, or watching TV. You and your eye care professional 

can make this decision together. Once you understand the 

benefits and risks of surgery, you can make an informed 

decision about whether cataract surgery is right for you. 

In most cases, delaying cataract surgery will not cause 

long-term damage to your eye or make the surgery more 

difficult. You do not have to rush into surgery.

Sometimes a cataract should be removed even if it does not 

cause problems with your vision. For example, a cataract 

should be removed if it prevents examination or treatment 

of another eye problem, such as age-related macular 

degeneration or diabetic retinopathy.

If you choose surgery, your eye care professional may refer 

you to a specialist to remove the cataract.

If you have cataracts in both eyes that require surgery, the 

surgery will be performed on each eye at separate times, 

usually four weeks apart.
8

8

Is cataract surgery effective?

Cataract removal is one of the most common operations 

performed in the United States. It also is one of the safest and 

most effective types of surgery. In about 90 percent of cases, 

people who have cataract surgery have better vision afterward.

What are the risks of cataract surgery?

As with any surgery, cataract surgery poses risks, such 

as infection and bleeding. Before cataract surgery, your 

doctor may ask you to temporarily stop taking certain 

medications that increase the risk of bleeding during 

surgery. After surgery, you must keep your eye clean, 

wash your hands before touching your eye, and use 

the prescribed medications to help minimize the risk of 

infection. Serious infection can result in loss of vision.

Cataract surgery slightly increases your risk of retinal 

detachment. Other eye disorders, such as high myopia 

(nearsightedness), can further increase your risk of retinal 

detachment after cataract surgery. One sign of a retinal 

detachment is a sudden increase in flashes or floaters. 

Floaters are little “cobwebs” or specks that seem to 

float about in your field of vision. If you notice a sudden 

increase in floaters or flashes, see an eye care professional 

immediately. A retinal detachment is a medical emergency.

If necessary, go to an emergency service or hospital. Your 

eye must be examined by a physician as soon as possible. 

A retinal detachment causes no pain. Early treatment for 

retinal detachment often can prevent permanent loss of 

vision. The longer the retina stays detached, the less likely 

you will regain good vision once you are treated. Even if 

you are treated promptly, some vision may be lost.
9

Talk to your eye care professional about these risks. Make 

sure cataract surgery is right for you.

What if I have other eye conditions and need cataract 

surgery?

Many people who need cataract surgery also have other 

eye conditions, such as age-related macular degeneration 

or glaucoma. If you have other eye conditions in addition 

to cataract, talk with your doctor. Learn about the risks, 

benefits, alternatives, and expected results of cataract 

surgery.

What happens before surgery?

A week or two before surgery, your doctor will do some 

tests. These tests may include measuring the curve of 

the cornea and the size and shape of your eye. This 

information helps your doctor choose the right type of 

intraocular lens (IOL).

You may be asked not to eat or drink anything 12 hours 

before your surgery.

What happens during surgery? 

At the hospital or eye clinic, drops will be put into your 

eye to dilate the pupil. The area around your eye will be 

washed and cleansed.

Treatment
10

10

The operation usually lasts less than one hour and is almost 

painless. Many people choose to stay awake during surgery. 

Others may need to be put to sleep for a short time. If you 

are awake, you will have an anesthetic to numb your eye.

After the operation, a patch may be placed over your eye. 

You will rest for a while. Your medical team will watch for 

any problems, such as bleeding. Most people who have 

cataract surgery can go home the same day. You will need 

someone to drive you home.

What happens after surgery?

Itching and mild discomfort are normal after cataract 

surgery. Some fluid discharge is also common. Your eye 

may be sensitive to light and touch. If you have discomfort, 

your doctor can suggest treatment. After one or two days, 

moderate discomfort should disappear.

For a few weeks after surgery, your doctor may ask you 

to use eyedrops to help healing and decrease the risk of 

infection. Ask your doctor about how to use your eyedrops, 

how often to use them, and what effects they can have. 

You will need to wear an eye shield or eyeglasses to help 

protect your eye. Avoid rubbing or pressing on your eye.

When you are home, try not to bend from the waist to pick 

up objects on the floor. Do not lift any heavy objects. You 

can walk, climb stairs, and do light household chores.

In most cases, healing will be complete within eight weeks. 

Your doctor will schedule exams to check on your progress.
11

Can problems develop after surgery?

Problems after surgery are rare, but they can occur. These 

problems can include infection, bleeding, inflammation (pain, 

redness, swelling), loss of vision, double vision, and high or low 

eye pressure. With prompt medical attention, these problems 

usually can be treated successfully.

Sometimes the eye tissue that encloses the IOL becomes cloudy 

and may blur your vision. This condition is called an aftercataract. An after-cataract can develop months or years after 

cataract surgery.

An after-cataract is treated with a laser. Your doctor uses a 

laser to make a tiny hole in the eye tissue behind the lens 

to let light pass through. This outpatient procedure is called 

a YAG laser capsulotomy. It is painless and rarely results in 

increased eye pressure or other eye problems. As a precaution, 

your doctor may give you eyedrops to lower your eye pressure 

before or after the procedure.

When will my vision be normal again?

You can return quickly to many everyday activities, but 

your vision may be blurry. The healing eye needs time to 

adjust so that it can focus properly with the other eye, 

especially if the other eye has a cataract. Ask your doctor 

when you can resume driving.

Treatment
12

12

If you received an IOL, you may notice that colors are very 

bright. Most IOLs are clear, unlike your natural lens that 

may have had a yellowish/brownish tint. Within a few 

months after receiving an IOL, you will become used to 

improved color vision. Also, when your eye heals, you will 

most likely need new glasses or contact lenses.

What can I do if I already have lost some vision from 

cataract?

If you have lost some vision, speak with your surgeon 

about options that may help you make the most of your 

remaining vision. 

What can I do to protect my vision?

Wearing sunglasses and a hat with a brim to block 

ultraviolet sunlight may help to delay cataract. If you 

smoke, stop. Researchers also believe good nutrition 

can help reduce the risk of age-related cataract. They 

recommend eating green leafy vegetables, fruit, and other 

foods with antioxidants.

If you are age 60 or older, you should have a 

comprehensive dilated eye exam at least once every two 

years. In addition to cataract, your eye care professional 

can check for signs of age-related macular degeneration, 

glaucoma, and other vision disorders. Early treatment for 

many eye diseases may save your sight.
13

What research is being done?

The National Eye Institute is conducting and supporting a 

number of studies focusing on factors associated with the 

development of age-related cataract. These studies include:

• The effect of sunlight exposure, which may be associated 

with an increased risk of cataract.

• Vitamin supplements, which have shown varying results 

in delaying the progression of cataract.

• Genetic studies, which show promise for better 

understanding cataract development.

What should I ask my eye care professional?

You can protect yourself against vision loss by working in 

partnership with your eye care professional. Ask questions 

and get the information you need to take care of yourself 

and your family.

What are some questions to ask?

About my eye disease or disorder...

• What is my diagnosis?

• What caused my condition?

• Can my condition be treated?

• How will this condition affect my vision now and in the 

future?

What You Can Do
14

14

• Should I watch for any particular symptoms and notify 

you if they occur?

• Should I make any lifestyle changes? 

About my treatment...

• What is the treatment for my condition? 

• When will the treatment start and how long will it last? 

• What are the benefits of this treatment and how 

successful is it? 

• What are the risks and side effects associated with this 

treatment?

• Are there foods, drugs, or activities I should avoid while 

I’m on this treatment? 

• If my treatment includes taking medicine, what should I 

do if I miss a dose? 

• Are other treatments available?

About my tests...

• What kinds of tests will I have? 

• What can I expect to find out from these tests? 

• When will I know the results? 

• Do I have to do anything special to prepare for any of 

the tests? 

• Do these tests have any side effects or risks? 

• Will I need more tests later?
15

Other suggestions

• If you don’t understand your eye care professional’s

responses, ask questions until you do understand.

• Take notes or get a friend or family member to take

notes for you. Or, bring a tape recorder to help you 

remember the discussion.

• Ask your eye care professional to write down his or her

instructions to you.

• Ask your eye care professional for printed material

about your condition.

• If you still have trouble understanding your eye care

professional's answers, ask where you can go for more

information.

• Other members of your health care team, such as nurses

and pharmacists, can be good sources of information.

Talk to them, too.

Today, patients take an active role in their health care. Be 

an active patient about your eye care.

What You Can Do
16

16

Where can I get more information?

For more information about cataract, you may wish to 

contact:

American Academy of Ophthalmology

P.O. Box 7424

San Francisco, CA 94109–7424

415–561–8500

www.aao.org

www.eyecareamerica.org (Online Referral)

American Optometric Association

243 North Lindbergh Boulevard, Floor 1

St. Louis, MO 63141–7851

314–991–4100

www.aoa.org

National Eye Institute

National Institutes of Health

2020 Vision Place

Bethesda, MD 20892–3655

301–496–5248

Email: 2020@nei.nih.gov

www.nei.nih.gov

Prevent Blindness

211 West Wacker Drive, Suite 1700

Chicago, IL 60606

1–800–331–2020

Email: info@preventblindness.org

www.preventblindness.org
17

Additional Resources

For more information about IOLs, contact:

U.S. Food and Drug Administration

Consumer Health Information

10903 New Hampshire Avenue

Building 32, Room 5377

Silver Spring, MD 20993

1-888-463-6332

Email: consumerInfo@fda.hhs.gov

www.fda.gov

American Foundation for the Blind

2 Penn Plaza, Suite 1102

New York, NY 10121

1-800-232-5463

212-502-7600

Email: afbinfo@afb.net

www.afb.org
18

18

Notes

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

National Institutes of Health

National Eye Institute

Revised 09/15