A cataract is a clouding of the eye's lens. The vast majority of cataracts are related to age. Most people do not even realize they have a cataract, as cataracts grow very slowly and may not impede vision early on. After a number of years vision will likely be affected. When the cataract has become so dense that it compromises the patient's quality of life, the patient and ophthalmologist will discuss the appropriate time to remove it. Surgery is the only treatment.
What Causes a Cataract?
The human lens is transparent so that light can travel through it easily. It has no blood supply. It is 65% water. Although new cells are being made for the lens continuously throughout our lifetime, many factors combine as we age to cause areas in the lens to become cloudy, hard, and dense. The lens can then no longer transmit a clear picture to the retina where it can be processed and sent through the optic nerve to the brain.
What are the Different Types of Cataract?
- Although it is not common, some babies are born with cataracts or develop them within the first year of life.
- This type of cataract results from an injury to the eye.
- This is a cataract that is caused either by medications (most commonly prednisone or other corticosteroids) or disease, like diabetes. Cataracts are 10 times more common in diabetic patients than in the general population.
- The most common kind of cataract. There are three subclassifications, based on location: nuclear, cortical and posterior subcapsular.
Facts and Figures
- By age 65, over 90% of people have a cataract
- 50% of people between the ages of 75 and 85 have lost some vision because of a cataract
- In the United States, cataract surgery is the most frequent therapeutic procedure performed on people age 65 and above
- Over 2 million cataract procedures are performed in the United States every year and include patients who range from newborn to those in their 90s
- Cataract is the most common cause of blindness in the world, although it is treatable.
Typically patients will experience blurry vision, double vision, sensitivity to light, glare, colors that appear washed out, and frequent changes to eyeglass prescription. An ophthalmologist or optometrist will be able to diagnose a cataract by looking through a slit-lamp during a dilated eye examination or by looking through an ophthalmoscope.
Surgical removal of cataracts and replacement with an artificial lens (called an intraocular lens) is the most successful surgical procedure in the country. This is performed on an out-patient basis under local anesthesia.
Although there is no surefire way to prevent cataracts from forming, there is evidence to show that protecting your eyes from ultraviolet light may prevent or slow the progression of cataracts. Smoking also increases the rate of cataract formation, so stopping smoking will decrease the risk.
Mythbusters - Facts about Cataracts
- Cataracts do not travel from one eye to the other
- Cataracts are not caused by using the eyes too much
- Cataracts are not related to cancer
- Cataracts cannot be treated or removed with a laser
For more information, see the Comprehensive Ophthalmology and Cataract Sugery Clinic and the complete Clinic Services listing of the U-M Kellogg Eye Center.