Cataract: Symptoms, diagnosis, and treatment

The eye's lens is a clear structure that focuses images on the light-sensitive retina. A cataract is a clouding of the lens. This distorts or blocks the passage of light through the lens, causing cloudy or blurred vision, other visual problems, and even blindness. The name cataract comes from the term for "huge waterfall," which is how some people describe their clouded sight: like trying to look through a waterfall.e274c687-dcd5-438e-bb9c-7769382a582e16207266889531

It usually takes years for the clouding of the lens to keep light from reaching the retina or distorting light rays.

Cataracts are usually an age-related condition. They first appear in the 40s or 50s, but may not affect vision until much later. Some cataracts are caused by an injury to the eye, long-term diabetes, the use of corticosteroid medications, or radiation treatment.

Some babies are born with cataracts, or develop them because of an infection that happened during pregnancy, such as toxoplasmosis, cytomegalovirus, syphilis, rubella, or herpes simplex. In infants and young children, cataracts also can be one symptom of a disease that affects how the body processes carbohydrates, amino acids, calcium or copper.

Cataracts are the world's leading cause of blindness, accounting for half of all cases of blindness.

Symptoms of cataract

Cataracts typically do not cause any symptoms until they have grown large enough to interfere with vision. Symptoms include:

  • cloudy or blurry vision
  • double vision
  • colors appear faded
  • seeing halos around lights
  • increased sensitivity to glare

Diagnosing cataract

Your story of your visual symptoms is an important part of diagnosing cataract. Your eye doctor will likely widen (dilate) your pupils with medication and examine your eyes, and give you a visual acuity test to check your vision.

Treating cataract

People with cataracts can use eyeglasses, magnifying lenses, or stronger lighting to help improve their vision. But the only way to cure a cataract is with surgery. Before going ahead with surgery, it's important to weigh how bad your vision is against the small risk of surgery and the likelihood that it will improve your vision.

Cataract surgery involves removing the clouded lens and replacing it with a plastic lens inserted in the eye during surgery.

Cataract surgery improves the vision of most — but not all — people who have it. In some people, the surgery causes posterior capsule opacification, in which the part of the eye behind the artificial lens becomes cloudy. This can be corrected with laser surgery.


As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Free Healthbeat Signup

Get the latest in health news delivered to your inbox!

Sign Up
Harvard Health Publishing Logo

Thanks for visiting. Don't miss your FREE gift.

The Best Diets for Cognitive Fitness, is yours absolutely FREE when you sign up to receive Health Alerts from Harvard Medical School

Sign up to get tips for living a healthy lifestyle, with ways to fight inflammation and improve cognitive health, plus the latest advances in preventative medicine, diet and exercise, pain relief, blood pressure and cholesterol management, and more.

Harvard Health Publishing Logo

Health Alerts from Harvard Medical School

Get helpful tips and guidance for everything from fighting inflammation to finding the best diets for weight loss...from exercises to build a stronger core to advice on treating cataracts. PLUS, the latest news on medical advances and breakthroughs from Harvard Medical School experts.

BONUS! Sign up now and
get a FREE copy of the
Best Diets for Cognitive Fitness

Harvard Health Publishing Logo

Stay on top of latest health news from Harvard Medical School.

Plus, get a FREE copy of the Best Diets for Cognitive Fitness.