Cataracts

Reviewed by Dr. Clement J. Cheng

The lens of the human eye is made mostly of water and protein. The protein is arranged to let light pass through and focus on the retina. Sometimes some of the protein clumps together and starts 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 difficult to see.

Cataracts are painless. When a cataract is small, you may not notice any changes in your vision. Cataracts tend to grow slowly, so vision deteriorates gradually. Some people with a cataract find that their close-up vision suddenly improves, but this is temporary. Vision is likely to get worse again as the cataract grows.

• Cloudy or blurry vision
  
• Problems with light, such as headlights that seem too bright at night, glare from lamps or the sun, or a halo or haze around lights
  
• Colors that seem faded
  
• Double or multiple vision (this symptom goes away as the cataract grows)
  
• Frequent changes in your eyeglasses or contact lenses
  

The different types of cataract are:

• Age-related cataract: This is the most common type of cataract.
  
• Congenital cataract: Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may not affect vision. If they do, they may need to be removed.
  
• Secondary cataract: Cataracts are more likely to develop in people who have certain other health problems, such as diabetes. Also, cataracts are sometimes linked to steroid use.
  
• Traumatic cataract: Cataracts can develop soon after an eye injury, or years later.
  

To detect a cataract, an eye care professional examines the lens. A trained ophthalmologist can identify a cataract simply by observing a cloudy area on the lens. In addition, a comprehensive eye examination is performed.

The eye test includes the following items:

• Visual acuity test: This eye chart test measures how well you see at various distances with the Snellen eye chart.
  
• Pupil dilation: The pupil is widened with eye drops to allow your eye care professional to see more of the retina and look for other eye problems.
  
• Tonometry: This is a standard test to measure fluid pressure inside the eye. Increased pressure may be a sign of glaucoma.
  
• Your eye care professional may also do other tests to learn more about the structure and health of your eye.
  

A cataract needs to be removed only if it affects your vision so much that it interferes with your daily activities. You make that decision. If you decide on cataract surgery, your eye care professional may refer you to another specialist to remove the cataract. If you have cataracts in both eyes, the surgeon will not remove them both at the same time. You will need to have each done separately.

Sometimes, a cataract should be removed even if it doesn't bother you. For example, if it prevents examination or treatment of another eye problem such as age-related macular degeneration or diabetic retinopathy, a cataract should be treated.