Health Library CataractsFrom Healthwise

What is a cataract?

A cataract is a painless, cloudy area in the lens of the eye that blocks the passage of light to the retina. The retina is the nerve layer at the back of the eye. The nerve cells in the retina detect light entering the eye and send nerve signals to the brain about what the eye sees. Because cataracts block this light, they can cause vision problems.

See a picture of a cataract.

What causes cataracts?

Aging and exposure to sunlight can cause cataracts. Changes in your eyes are often a normal part of aging, but they do not always lead to cataracts.

Cataracts can also happen after an eye injury, as a result of eye disease, after you use certain medicines, or as a result of health problems such as diabetes.

Sometimes children are born with cataracts.

What are the symptoms?

Cataracts can affect your vision.

• You may have cloudy, fuzzy, or foggy vision.
• You may see glare from lamps or the sun. You may have trouble driving at night because of glare from car headlights.
• You may need frequent changes to your eyeglasses prescription.
• You may get double vision in one eye.
• Your near vision may improve for a short time if you get a cataract. This temporary improvement is called second sight.

Sometimes cataracts do not cause vision problems.

How are cataracts diagnosed?

Your doctor can find out if you have cataracts by doing a physical exam and by asking questions about your symptoms and past health. You may need other tests to make sure you have a cataract or to rule out other conditions that may be causing vision problems.

How are they treated?

Surgery is the only way to correct vision loss caused by cataracts. But cataracts in older adults do not always need to be removed. The vision loss from a cataract often happens slowly and may never become severe.

There are a number of things you can do that may help you manage your vision problems. Many people get along very well with the help of eyeglasses, contacts, or other vision aids. Keep your eyeglasses or contact lens prescription up to date. Also make sure you have plenty of lighting in your home. You may be able to avoid or delay surgery.

Whether you need cataract surgery depends on how much of a problem the cataract causes for daily activities like driving and reading. Surgery is almost always by your choice (elective) and can be scheduled when it is convenient. For people who do decide to have surgery, the surgery usually works very well.

Some people have to have surgery. Children are sometimes born with cataracts that need to be removed. Other people may get cataracts after an eye injury or as a result of eye disease or other health problems. Cataracts from these causes may also need to be removed.

How can I prevent cataracts?

There is no proven way to prevent cataracts. But there are some things you can do that may help slow cataract growth. Do not smoke. Wear a hat or sunglasses when you are in the sun, and avoid sunlamps and tanning booths. Eat healthy foods, and limit alcoholic drinks. Keep diabetes under control.

Frequently Asked Questions

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	Should I have cataract surgery?

A cataract occurs when the lens inside your eye becomes cloudy. Factors associated with clouding include:

• Aging (age-related cataracts).
• Overexposure to ultraviolet (UV) radiation, such as from sunlight, tanning booths, or sunlamps.
• Diabetes. Diabetes, especially when the blood sugar levels are above the safe range, causes changes in the eye that can result in cataracts.
• Disease inside the eye, such as glaucoma, long-term (chronic) uveitis, retinitis pigmentosa, or retinal detachment.
• Long-term use of steroid medicines.
• Frequent X-rays or radiation treatments to the head.
• Family history (genetics). A person may inherit the tendency to develop cataracts.
• Vitrectomy. People older than age 50 who have had the vitreous gel removed from their eye (vitrectomy) have an increased risk of cataracts. Some studies show that up to 80% of older people develop cataracts between 6 months and 3 years after vitrectomy.¹
• Eye injury. Even though injury-related cataracts are rare, injury is a leading cause of cataracts in children.
• Being born with cataracts (congenital). Some children are born with the condition.

Not all cataracts impair vision or affect daily living. For those that do, common symptoms include:

• Cloudy, fuzzy, foggy, or filmy vision.
• Glare from lamps or the sun, which may be severe.
• Difficulty driving at night due to glare from headlights.
• Frequent changes in eyeglass prescription.
• Double vision.
• Second sight.
• Difficulty performing daily activities because of vision problems.

Parents need to watch for signs of cataracts in infants and children.

Cataracts may remain small and may not be noticeable. They often do not seriously affect vision, and many cataracts do not need to be removed.

Some cataracts grow larger or denser over time, causing severe vision changes.

• Severe cataracts can cause loss of independence for older adults as decreased vision may affect driving, working, reading, or hobbies.
• While cataracts can cause blindness, this is rare. Surgery is usually done before a cataract progresses far enough to cause blindness.
• A rare type of cataract can lead to glaucoma.

As a cataract progresses, more of the lens becomes cloudy. When the entire lens is white, the cataract is called a "ripe" or "mature" cataract and causes severe vision problems. Delaying surgery until cataracts are ripe or mature is neither recommended nor necessary.

Cataracts in children are rare but serious. If a cataract prevents light from entering a child's eye and stimulating the retina, the area of the brain used for sight does not develop properly. Usually, the child won't see well with that eye ( amblyopia), even if the cataract is later removed.

Risk factors for cataracts include:

• Age. Getting older is a major risk factor for cataracts.
• Sex. Women are at slightly higher risk than men for cataracts. But it is unclear whether this applies to all types of cataracts or only to certain types.
• Family history (genetics). People with a family history of cataracts are more likely to have cataracts. People with certain genetic disorders also have an increased risk of cataracts. These disorders include myotonic dystrophy, the most common form of muscular dystrophy in adults, and galactosemia, a rare disorder that involves elevated levels of the sugar galactose in the blood.²

Some chronic diseases increase the risk for cataracts. Keeping these diseases under control may help lower your risk of developing cataracts:

• Diabetes. People with diabetes are at increased risk for cataracts. Damage to the lens of the eye results from persistent high blood sugar (glucose) levels.¹
• Glaucoma. Certain medicines that are used to treat glaucoma may increase the risk of developing a cataract. Surgery to treat glaucoma also increases the risk of cataracts.

Other factors that increase your risk include:

• Smoking. People who smoke are more likely to develop cataracts. Smoking may damage the lens of the eye by leading to the formation of chemicals called free radicals. High levels of free radicals can damage cells, including those in the lens of the eye.
• Infection during pregnancy. If a woman has certain infections during pregnancy, such as rubella or chickenpox, the baby may develop a cataract before birth.
• Ultraviolet (UV) light exposure. Ultraviolet B (UVB) is related to cataract development. Studies have shown that high lifetime exposure to ultraviolet light, as in those whose occupations result in regular exposure to sunlight, leads to an increased chance of developing cataracts.¹
• Alcohol use. Some studies show that heavy drinking may increase the risk of cataracts.¹
• Long-term use and higher doses of steroid medicines. Long-term use of high doses of steroid medicines for conditions such as asthma or emphysema increases a person's risk of developing cataracts.¹
• High triglycerides. One study suggested that elevated levels of triglycerides, a form of fat that can accumulate in the walls of your arteries, may increase the risk of cataracts in men.³

Call your doctor immediately if you have:

• Severe eye pain.
• A sudden change in your vision, such as loss of vision or double vision.

Call your doctor to discuss your symptoms if you:

• Need frequent changes in your eyeglasses prescription.
• Have blurred or double vision that develops slowly.
• Are having a problem seeing during the daytime because of glare.
• Have difficulty driving at night because of glare from headlights.
• Have vision problems that are affecting your ability to perform daily activities.

If you are an older adult, discuss with your health professional how often you need to have routine eye exams.

If a doctor has not determined that you have cataracts but you have symptoms that concern you, see the topic Eye Problems, Noninjury to find more information on what to do about your symptoms.

Watchful Waiting

Watchful waiting is a wait-and-see approach. Watchful waiting is safe and appropriate in most cases of adult cataracts. If you think your child has a cataract, see your health professional. Cataracts in children should be treated right away.

Speak with an ophthalmologist about surgery to remove cataracts. In most cases, you can decide if you want or need surgery based on whether vision problems caused by the cataract are interfering with your daily activities.

Who To See

The following health professionals can evaluate vision problems that may be caused by a cataract:

• Ophthalmologist
• Optometrist
• Nurse practitioner
• Physician assistant
• Family medicine doctor
• Internist
• Pediatrician

While other health professionals may be able to detect problems that may be caused by cataracts, only an ophthalmologist can treat cataracts.

An ophthalmologist can help with the decision to have surgery and can perform the surgery, if necessary.

To prepare for your appointment, see the topic Making the Most of Your Appointment

Diagnosis of cataracts is based on a medical history and physical examination.

Often tests are used to:

• Confirm the presence of a cataract.
• Rule out other conditions that may be causing vision loss.

For more information, see the topics Vision Tests, Ophthalmoscopy, and Tonometry.

In deciding whether to have surgery, it can be very helpful to evaluate the effect that vision loss from a cataract has on your life. Your doctor may ask you to complete a questionnaire regarding the effect of the cataract on daily activities.

If you have already experienced some vision loss that cannot be corrected by cataract surgery, your doctor also may perform a low-vision evaluation to help find ways for you to make the most of your remaining vision and maintain your quality of life.

Early Detection

Routine screening for cataracts in adults is not necessary since most adults have an eye exam when they are having vision problems.

Testing your child for cataracts may be necessary if you think your child is having a vision problem.

Currently, surgery is the only effective method of treating vision loss caused by cataracts.

Cataract surgery is a common procedure that involves removing the clouded lens of the eye (the cataract). The lens makes it possible for the eye to focus (see a picture of the lens). The lens can be replaced with an artificial lens called an intraocular lens implant (IOL), or it can be left out and eyeglasses or contact lenses can compensate for its absence. For more information about IOL implants, see intraocular lens to replace the natural lens of the eye.

Surgery is often not necessary or can be delayed for months or years. Many people with cataracts get along very well with the help of eyeglasses, contacts, and other vision aids.

The choices for treating cataracts in children depend on how likely the cataracts are to interfere with development of normal vision.

Whether surgery is needed for an adult with cataracts depends on the degree of vision loss and whether it affects quality of life and ability to function.

Should I have cataract surgery?

What to Think About

Occasionally a cataract needs to be removed because of another eye disease, such as diabetic retinopathy or macular degeneration. In some cases the cataract has to be removed so that the eye specialist can treat the retina, the nerve layer at the back of the eye.

Misconceptions about cataracts are common. In recent years, an increasing number of medical facilities have been built specifically for cataract surgery. Marketing campaigns aimed at older adults may encourage some people to have surgery when they do not really need it. Because of fear of blindness or loss of independence, older adults may think they need to have surgery even when their cataracts do not affect their quality of life. In many cases, wearing eyeglasses or contacts and using other vision aids might be appropriate and just as effective without any of the risks of surgery.

Only you can decide whether a cataract is affecting your vision and your life enough to have surgery. If surgery is not going to improve your vision, you may decide that surgery is not for you.

There is no proven way to prevent cataracts. However, certain lifestyle habits may help slow cataract development. These include:

• Not smoking.
• Wearing a hat or sunglasses when you are in the sun and avoiding sunlamps and tanning booths.
• Eating a diet rich in vitamins C and E. Eat at least 3 servings of fresh fruits or green, leafy vegetables, and take a multivitamin every day. There is no solid proof that these foods prevent cataracts, but researchers are studying this.
• Limiting your alcohol intake.
• Avoiding the use of steroid medicines when possible (some people need them).
• Keeping diabetes under control.

If you have cataracts, these tips and vision aids may help you manage your vision problems and avoid or delay surgery:

• Tips for improving vision include repositioning lights and keeping your eyeglass or contact lens prescription up to date.
• Low-vision accommodations in your home, such as using adequate lighting and adjusting carpets and furniture to avoid potential hazards, can make living with low vision easier and safer.
• Low-vision aids and adaptive technologies such as video enlargement systems or speech software for computer systems can help people with impaired vision make the best use of their remaining vision.

Evidence indicates that making certain lifestyle changes such as not smoking and protecting your eyes from sunlight may help slow the development of cataracts. For more information, see the Prevention section of this topic.

After cataract surgery

Your doctor will give you instructions about what to do after cataract surgery. Eye care for adults after cataract surgery includes using prescribed eyedrops, protecting your eye, and watching for signs of infection.

Contact your doctor promptly if you notice any signs of complications, such as:

• Decreasing vision.
• Increasing pain.
• Increasing redness.
• Swelling around the eye.
• Any discharge from the eye.
• Any new floaters, flashes of light, or changes in your field of vision.

It is normal to have blurred vision and some swelling after surgery. It takes time for the swelling to go down. Your eyeglass prescription may change after surgery.

A small number of adults and children with cataracts may benefit for a short time from eyedrops that widen (dilate) the pupil. These eyedrops increase the amount of light getting into the eye. They may also be used in children under age 2 who have cataracts, to prevent loss of vision until surgery can be done.

Medication Choices

Mydriatic eyedrops

What To Think About

There is currently no medicine that will cure cataracts.

Surgery for a cataract involves removing the clouded lens of the eye (the cataract). The lens can be replaced with an artificial lens called an intraocular lens implant (IOL). Or, if an IOL cannot be used for any reason, it will be left out and contact lenses or, rarely, eyeglasses can compensate for its absence. Most people will get an IOL during surgery.

Before surgery, review with your doctor the pros and cons of each type of IOL available. Or, if you will not be getting an IOL, the pros and cons of contact lenses or eyeglasses.

• Intraocular lens (IOL). A variety of IOL types are available. Your doctor will choose the type of IOL that may work best for you.
• Contact lens. A contact lens is placed on the surface of the eye. A contact lens may not be a good choice for young children or older adults who have a hard time properly placing the lens in the eye.
• Cataract glasses. Cataract glasses were used for decades when there were no other options for lens replacement. Because they are thick and heavy, they are rarely used now.

For most adults, surgery is only needed when vision loss caused by a cataract affects your quality of life. The goals of surgery in adults with cataracts include:

• Improving vision.
• Helping you return to work, leisure, and other daily activities.

Should I have cataract surgery?

The choices for treating cataracts in children depend on how likely the cataracts are to interfere with development of normal vision. Surgery for cataracts in children may be necessary.

Before you have surgery for cataracts, tell your doctor all of the medicines you are currently taking. Your doctor may advise you to stop taking a medicine, such as an alpha-blocker (for example, terazosin) before the surgery to prevent complications.

Second surgery

For adults who have cataracts in both eyes, surgery is not normally done on both eyes at the same time. The first eye needs to heal, and your doctor will determine how much eyesight has improved before surgery is done on the second eye.

If you have both glaucoma and cataracts, you may have surgery for both conditions at the same time. Depending on which condition caused the vision loss, vision may improve after surgery.

Surgery Choices

There are two types of cataract surgery. The decision about which one to use depends on what kind of cataract you have and how much experience the surgeon has with each type of surgery.

• Phacoemulsification. In this type of surgery, the incisions are small, and sound waves (ultrasound) are used to break up the lens into small pieces. Currently, this is the most common method of doing cataract surgery.
• Extracapsular surgery. In this type of surgery, the lens and the front portion of the lense capsule wrapped around the lens is opened. The lens is then carefully removed in one piece. Some techniques use a small incision and manually break up the lens into small pieces. Extracapsular surgery is also called extracapsular cataract extraction (ECCE).

In the past, cataracts were removed by intracapsular surgery, in which the entire lens and lens capsule were removed. Intracapsular surgery is rarely, if ever, used today. It is more difficult and has a higher rate of complications than extracapsular procedures.

About 1 out of 4 people who have cataract surgery develop clouding of the posterior lens capsule (called aftercataract) within 5 years after surgery.⁴ But this clouding is usually not a serious problem, and it is easy to treat with a laser surgery (Nd:YAG laser posterior capsulotomy) if it develops. This type of surgery is done in an office setting.

What To Think About

For adults, cataract surgery is almost always elective and can be done at your convenience. The surgeon, or someone familiar with routine surgical practices, will usually be available for any follow-up exams and treatment.

If you do not have another eye condition, such as glaucoma or problems with your retina, your chances of seeing better after cataract surgery are very good. But you may still need reading glasses or glasses for near vision.

Just because you have a cataract does not mean you need to have it removed. Only you can decide whether cataracts are affecting your vision and your life enough to have surgery. Learn what you should ask about cataract surgery before deciding whether to have the surgery.

With the use of certain vision-boosting techniques and vision aids, many older adults may be able to avoid or delay having cataract surgery.

Other Treatment Choices

Tips for improving vision include repositioning room lights and keeping your eyeglasses prescription current.

Low-vision accommodations in your home range from adding adequate lighting to adjusting carpets and furniture to avoid potential hazards.

Low-vision aids and adaptive technologies include video enlargement systems and speech software for computer systems.

What To Think About

Vision aids can be used for a short time, while you are deciding on surgery, or on a long-term basis, to avoid surgery.

Surgery may be advisable if you want to continue to drive a car. If you live in a retirement home or assisted-living facility, you may decide to use vision aids and avoid surgery.

Organizations

• Eye Problems, Noninjury

Citations

1. Beebe DC (2003). The lens. In PL Kaufman, A Alm, eds., Adler's Physiology of the Eye, 10th ed., pp. 117–158. St. Louis: Mosby.

2. Sugar A, ed. (2002) Cataract section of Lens. In DH Gold, RA Lewis, eds., Clinical Eye Atlas, pp. 762–778. Chicago: AMA Press.

3. Hiller R, et al. (2003). Serum lipids and age-related lens opacities: A longitudinal investigation. Ophthalmology, 110(3): 578–583.

4. Schaumberg DA, et al. (1998). A systematic overview of the incidence of posterior capsule opacification. Ophthalmology, 105(7): 1213–1221.

Other Works Consulted

• Allen D (2006). Cataract, search date October 2005. Online version of Clinical Evidence (15).

• SanGiovanni JP, et al. (2002). Infantile cataract in the collaborative perinatal project. Archives of Ophthalmology. 120(11): 1559–1565.

Author:	Jeannette Curtis	Last Updated: October 1, 2007
Medical Review:	Anne C. Poinier, MD - Internal Medicine Christopher J. Rudnisky, MD, FRCSC - Ophthalmology
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