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Normal eye


Alternative Names
clouding of the lens, opaque lens or capsule

A cataract is a spot on the eye that blocks light, or a blemish within the lens of the eye. This creates a hazy, cloudy, or frosty appearance. Cataracts interfere with vision.

What is going on in the body?
The natural lens of the eye is located behind the pupil and iris. It should be clear. The lens refracts or bends light rays coming into the eye. This causes the light rays to focus on the retina, producing clear vision. Any clouding of the lens will interfere with vision. Clouding of the lens develops through changes in the physical and chemical state of the lens proteins.

What are the signs and symptoms of the condition?
Symptoms include:
  • blurred vision
  • glare
  • increased sensitivity to light
  • rainbows or halos around lights
  • a feeling of looking through a haze or fog
Sometimes people may also notice differences in colours, ghost images, or double vision. Difficulty reading and night driving are also reported. Cataracts do not cause pain, redness, or discomfort.

What are the causes and risks of the condition?
Most cataracts develop during the normal course of ageing. Over time, the lens becomes firmer or more opaque. Infants and children can have cataracts, although this is rare. Some of the causes include:
  • heredity
  • infections before birth, such as measles
  • chromosomal problems, such as Down's syndrome
  • injury to the eye
  • exposure to high-voltage electricity, including lightning
  • premature birth
  • drug-related causes
  • radiation treatment around the eye
  • diabetes or other metabolic disorders
  • other general health problems such as Marfan's syndrome, which is an hereditary condition that damages the connective tissues
  • living at high altitudes with exposure to sunlight
What can be done to prevent the condition?
Some people take vitamins, minerals, and herbal extracts to decrease cataract formation. No scientific data proves that these remedies are effective. There are no proven topical or oral medications or supplements that decrease the chance of getting cataracts. A healthy lifestyle might help. This includes not smoking, eating a proper diet, and getting regular exercise and rest. These actions may prevent eye disease, just as they prevent other diseases in the body. Recent evidence suggests that wearing glasses that block ultraviolet light may help reduce the chance of getting cataracts or developing problems with the retina.

How is the condition diagnosed?
A diagnosis is made by an eye doctor using a microscope called a slit lamp. When the pupil is dilated, the doctor can see any cloudiness in the natural lens of the eye.

What are the long-term effects of the condition?
If left untreated cataracts become gradually more opaque with time. Certain types, including congenital cataracts, one that a person is born with, may not change for many years.

What are the risks to others?
The only risk to others from cataracts would occur if a person with poor vision continued to drive or operate machinery with impaired vision.

What are the treatments for the condition?
When cataracts first start to form, updating glasses prescriptions will improve vision. This will delay surgery. When vision cannot be improved any further with glasses and daily activities become too hard, it is time to remove the lens. The surgery for cataracts removes all of the inner and outer parts of the lens. The cloudy natural lens is replaced with an artificial lens called an intraocular (in-trah-ah-cue-lar) implant. Cataract surgery is usually done with a small incision. This allows speedy recovery. Topical or local anaesthesia is used to numb the area. It is almost always done on an outpatient basis. The operation usually takes less than 15 - 20 minutes and is almost always successful in producing better vision.

What are the side effects of the treatments?
Side effects of cataract surgery may include infection of the eye increased light sensitivity, or streaks or halos coming from lights. Sometimes people need to use their glasses more. Glaucoma or retinal detachment are rare complications of surgery. These risks should be discussed with the eye surgeon before the operation.

What happens after treatment for the condition?
Surgical treatment for cataracts usually results in excellent vision. If the individual has other problems besides the cataract, such as degeneration in the retina or optic nerve, the results will not be as good.

How is the condition monitored?
Monitoring the disease is done with simple observation over months or years. As a cataract progresses, visual sharpness decreases. More problems with daily tasks such as cooking, reading, and driving result. In addition to self-monitoring, the eye doctor can keep track of the disease through office examinations.

Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Potential conflict of interest information for reviewers available on request

This website and article is not a substitute for independent professional advice. Nothing contained in this website is intended to be used as medical advice and it is not intended to be used to diagnose, treat, cure or prevent any disease, nor should it be used for therapeutic purposes or as a substitute for your own health professional's advice.  All Health and any associated parties do not accept any liability for any injury, loss or damage incurred by use of or reliance on the information.


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