A cataract is a clouding of the eye's lens that causes decreased vision. The lens of the eye focuses light rays onto the retina, the light-sensitive tissue at the back of the eye. The image is then recorded on the retina, which allows us to see things clearly.

The lens of the eye is made primarily of water and protein. The protein is arranged in a way that keeps the lens clear and lets light pass through it. A cataract develops when some of the protein clumps together and starts to cloud an area of the lens. A cataract will not spread from one eye to the other, although many people develop cataracts in both eyes.

As the cataract matures and gets cloudier, it becomes more difficult to read and do other normal tasks. Some people with “ripe” cataracts describe their vision as “trying to see through a waterfall.” Many people are not aware that their vision is blurry since cataracts usually progress slowly. That is just one reason why regular comprehensive eye examinations are important.

What causes cataracts?

The exact cause of cataracts is not known, but a number of risk factors are known to contribute to their formation, including, but not limited to:


The most common risk factor for cataracts is age. Approximately half of all Americans between the ages of 65 and 75 have cataracts.

Diseases or Injuries

  • Medical conditions, such as:
    • Diabetes
    • Hypoparathyroidism
    • Rheumatoid arthritis or other autoimmune diseases
    • Those that require taking steroid medications for a long period of time
  • Congenital conditions like some birth defects, metabolic issues, chromosomal abnormalities like Down syndrome, or prenatal infections
  • Chronic eye disease, like uveitis or retinitis pigmentosa
  • Eye injuries from a cut, puncture, or hard blow
  • Eye surgeries, such as surgery for a retinal detachment
  • Certain infections
  • Family history of cataracts

Personal Behavior

  • Smoking
  • Excessive alcohol intake
  • Excessive exposure to sunlight

Environmental Factors

This can include exposure to radiation or toxins.

What are the symptoms of a cataract?

As a cataract develops, you may or may not notice changes in your vision. Cataracts tend to develop slowly, so vision gets worse gradually. Because the change happens over time, many people do not realize that they are losing vision. Some people with a cataract find that their close-up vision improves as the cataract matures, but this is just temporary. Vision will worsen as the cataract matures. Symptoms may include:

  • Cloudy or blurry vision
  • Poor contrast
  • Poor night vision
  • Difficulty reading
  • Double or multiple vision (often goes away as the cataract matures)
  • Increased nearsightedness, requiring frequent changes in your eyeglass or contact lens prescription
  • Colors seem faded or images appear with a yellow tint
  • Problems with light, including:
    • Headlights that seem too bright at night
    • Glare from lamps or very bright sunlight
    • A halo around lights
    • Trying to read in bright light
    • Problems when moving from a dark area to a bright area
  • Acute glaucoma attack (rare)

These symptoms also can be signs of other eye problems. If you have any of these symptoms, see your ophthalmologist immediately.

Are there different types of cataracts?

Yes, according to the National Eye Institute (NEI). In addition to cataracts that form as a result of aging, other types of cataracts include:

Secondary Cataracts

Cataracts can form after surgery for other eye problems, such as glaucoma. Cataracts also may develop in people who have other health problems, like diabetes, or that are linked to steroid use.

Traumatic Cataracts

Cataracts can develop after an eye injury, sometimes years later.

Congenital Cataracts

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 Cataracts

Cataracts can develop after exposure to some types of radiation.

How is a cataract diagnosed?

The only way to diagnose a cataract is with an eye examination. To detect a cataract, an ophthalmologist or optometrist examines the lens. Other tests evaluate the structure and overall health of the eye. A comprehensive eye examination for cataracts usually includes:

Visual Acuity Test

This eye chart test measures how well you see at various distances. This may include a test of your vision under conditions of low contrast and/or glare.

Dilated Eye Exam

The doctor gives you special eye drops to widen your pupils, which allows a more detailed examination of the lens and the structures of the back of your eyes.

Slit Lamp Exam

This is an examination of the eye using a specialized microscope that magnifies the eye.


This is a standard test to measure fluid pressure inside the eye since increased pressure may be a sign of glaucoma.

How is a cataract treated?

Treatment depends on how much cataracts affect your vision and quality of life. If you experience no issues, or only minor vision problems, you usually do not need treatment. Surgery is the only cure for cataracts, but making small adjustments in your lifestyle can help with managing or delaying symptoms. Surgery is recommended when symptoms progress to the point where they interfere with daily activities.

Lifestyle changes to slow the progression of cataracts include:

  • Wearing prescribed glasses or contact lenses
  • Wearing sunglasses to reduce glare and block ultraviolet UVA and UVB rays
  • Limiting driving
  • Wearing a hat
  • Avoiding fluorescent light to reduce glare
  • Considering nutritional supplements like antioxidant multivitamins

You should contact your eye doctor and discuss having surgery for cataracts when your vision difficulties get to the point where:

  • You feel unsafe or uncomfortable
  • You are unable to perform normal daily tasks or activities, such as:
    • Reading
    • Driving
    • Watching television
    • Cooking
    • Taking medications

Cataract surgery is much safer and more successful than in the past. Today, some eye doctors and surgeons recommend having cataract surgery sooner rather than later because delaying surgery may make it more difficult to perform down the road. Removing a cataract is rarely an emergency. It should not be performed until you feel ready to have the surgery.

Are there ways to prevent cataracts?

Approximately half of all Americans between the ages of 65 and 75 have cataracts. At this time, there is no definitive way to prevent age-related cataracts, but early diagnosis improves treatment outcomes. If you are over age 60, you should have an eye examination at least once every 1-2 years. You should have an eye examination more often if you have other risk factors, such as:

  • Diabetes
  • Glaucoma
  • High blood pressure
  • Rheumatoid arthritis or other autoimmune diseases
  • Any medical condition that requires you to take steroid medications for a long period of time
  • A family history of cataracts or other eye diseases