Skip to main content
URMC / Encyclopedia / Content


What are cataracts?

A cataract is a clouding of the lens in your eye. The lens is normally clear. When clouding occurs, it keeps light rays from passing through the lens and focusing on the retina. The retina is a thin layer of nerve tissue that lines the inside of the back of the eye and is sensitive to light. A cataract happens when the protein in the lens of your eye starts to break down and clump together. This causes the lens to become cloudy and affects your eyesight.

In its early stages, a cataract may not cause a problem. The cloudiness may affect only a small part of the lens. But as the cataract may grow larger over time, it may affect more of the lens. This can make it harder for you to see clearly. If less light reaches the retina, it becomes even harder to see. Your vision may become dull and blurry. Cataracts don't spread from one eye to another. But many people do get cataracts in both eyes.

There are many types of cataracts:

  • Age-related cataracts. This is the most common type of cataract. It is related to aging.

  • Congenital cataracts. Some babies are born with cataracts. Some children develop them in childhood, often in both eyes. Some congenital cataracts don't affect eyesight. Some do and must be removed.

  • Secondary cataracts. These often happen because of a disease in the body (such as diabetes). Secondary cataracts have also been linked to the use of steroid medicines.

  • Traumatic cataracts. An injury to one or both eyes may cause you to have a traumatic cataract. This can happen either right after the accident or years later.

What causes cataracts?

The cause of cataracts is not fully known. But these factors may be part of the cause:

  • Smoking

  • Alcohol

  • Diabetes

  • Nutritional deficiency

  • Unprotected exposure to UV sunlight

  • Steroid use

  • Some diuretic medicines

  • Some tranquilizer medicines

Who is at risk for cataracts?

Risk factors include:

  • Age. Age is the greatest risk factor for cataracts. Age-related cataracts may start to develop between ages 40 and 50.

  • Where you live. Recent studies have shown that people who live in high altitudes may be more at risk of having cataracts.

  • Too much sun exposure. People who spend more time in the sun, especially without eye protection, may have cataracts sooner.

What are the symptoms of cataracts?

Symptoms may be a bit different for each person. They may include:

  • Cloudy or blurry vision

  • Lights causing a glare or a halo

  • Poor night vision

  • Double vision

  • Colors seeming faded

  • Increased nearsightedness, and the need to change eyeglass prescriptions

You may not notice any changes in your vision in the early stages of a cataract. Cataracts tend to grow slowly, so your eyesight will get worse slowly. Some types of cataracts can also cause your close-up vision to get better for a short time., But your eyesight is likely to get worse as the cataract grows. The symptoms of cataracts may be like other eye conditions. Talk with an eye care provider for a diagnosis.

How are cataracts diagnosed?

To diagnose cataracts, your eye care provider will ask about your health history and give you an eye exam. You may also have tests, such as:

  • Visual acuity test.  The common eye chart test that measures vision.

  • Pupil dilation. The pupil is widened (dilated) with eye drops to allow a close-up exam of the retina.

You may have other tests to help your eye care provider learn more about the health of your eye.

How are cataracts treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how bad the condition is.

In its early stages, vision loss caused by a cataract may be helped by using different eyeglasses, a magnifying glass, or stronger lighting. When these are no longer helpful, surgery is the only effective treatment. A cataract only needs to be removed when vision loss gets in the way of your daily activities. These include driving, reading, or watching TV. You and your eye care provider can make that decision together.

Cataract surgery is one of the most common surgeries in the U.S. It is also one of the safest and most effective. It is done by replacing the cloudy lens with a new, artificial (manmade) lens. If you have cataracts in both eyes, they are not usually taken out at the same time. Your eye care provider will need to do the surgery on each eye separately.

First, the lens is removed. This is done in one of two ways:

  • Small incision cataract surgery (phacoemulsification). This is the most common type of cataract surgery. The surgeon makes a small cut (incision) on the edge of the cornea. The cornea is the clear, dome-shaped surface that covers the front of the eye. A tiny probe uses ultrasound waves to break up the cloudy center of the lens. The lens is then removed by suction through the same incision.

  • Extracapsular surgery. During this surgery, a larger incision is made on the edge of the cornea to remove the hard center of the lens in one piece. The rest of the lens is then taken out by suction.

Then, a new lens is put into the eye. It is a clear, artificial intraocular lens (IOL). With an IOL, a person often has better eyesight. That's because light will be able to pass to the retina. You won't see or feel the new lens. It is now part of your eye like your old lens.

What are possible complications of cataracts?

A possible complication of cataract surgery is an after-cataract. This happens when part of the natural lens that is purposely not taken out during cataract surgery becomes cloudy and blurs your eyesight. Unlike a cataract, an after-cataract can be treated with a method called YAG laser capsulotomy. The surgeon uses a laser beam to make a hole in the cloudy membrane behind the lens to let the light pass through. After-cataracts may occur months, or even years, after cataract surgery.

Key points about cataracts

  • A cataract is a clouding of the lens of the eye.

  • As a cataract develops, your eyesight may become blurry.

  • You may have halos around lights, double vision, and poor night vision. Colors may seem faded.

  • In its early stages, vision loss caused by a cataract may be helped by using different eyeglasses, a magnifying glass, or stronger lighting.

  • Over time, cataract surgery may be needed to improve your eyesight.

  • Cataract surgery is one of the safest and most effective surgeries.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.

  • Before your visit, write down questions you want answered.

  • Bring someone with you to help you ask questions and remember what your provider tells you.

  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

  • Ask if your condition can be treated in other ways.

  • Know why a test or procedure is recommended and what the results could mean.

  • Know what to expect if you do not take the medicine or have the test or procedure.

  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.

  • Know how you can contact your healthcare provider if you have questions, especially after office hours or on weekends and holidays.

Medical Reviewers:

  • Chris Haupert MD
  • Tara Novick BSN MSN
  • Whitney Seltman MD