Eye Disorders: Cataract causes, symptoms, and treatments.
For information about new lens implants that can help you become less dependent on glasses after cataract surgery, click on the cataract link above
What is a cataract?
A cataract is a progressive clouding of the lens of the eye that results in a decrease in vision. In the picture on the right, the pupil should be black, but a cataract is causing the haze. The diagram illustrates where in the eye cataracts form. Cataracts are very common. In fact, everyone will get a cataract if they live long enough. In that sense, a cataract is considered more "normal aging" than a disease.
What causes cataracts?
Cataracts are caused by oxidative damage to lens cells, which causes them to change from clear to cloudy. Oxidative damage normally occurs in the cells of our body, which leads to other aging changes we all experience. Oxidative change can be hastened by UV light exposure (the harmful sun rays that burn skin and promote skin cancer), and a diet poor in anti-oxidants. Genetics can play a role in early cataract development; in fact some people are born with a cataract. A cataract can be associated with certain medications, like Prednisone, and certain diseases, like diabetes. Inflammatory disorders of the eye, like Iritis or Uvietis, can cause cataracts. Still another cause of a cataracts may be trauma to the eye.
What are the symptoms of a cataract?
It is common to compare the function of the eye to a camera. The eye's lens focuses light onto the retina in the back of the eye, much like a camera's lens focuses light onto the film. A cataract blocks light from entering the eye, causing the vision to be blurry, like if the lens of a camera was blurry. Other common symptoms of a cataract include glare and halos around lights at night, difficulty seeing in the dark, double "shadow" vision, and impaired vision in bright light.
Examples of common visual symptoms would include difficulty seeing to drive, especially in unfamiliar areas when it is necessary to read road signs. It can become difficult to engage in some hobbies, like seeing to aim a rifle, or follow a golf ball. Some people are concerned about not being able to read smaller print on the TV, like game scores or news type. Night vision, with glare, can be very bothersome, limiting driving. Sometimes bright light on a sunny day, on a lake, or sun through a window can degrade vision. Detailed near activities, like threading a needle or stitching, can become difficult. Reading grey-on-grey type, like small newspaper print, can be impaired.
Can cataracts be prevented?
At this time there is no effective preventive therapy for cataracts. There is some evidence from population studies that antioxidant vitamins and UV blocking sunglasses may slow a cataract's growth.
When should I have cataract surgery (is my cataract "ripe")?
The decision to have surgery usually depends on how you are doing with your vision. When the quality of your life would be better if you could see better, cataract surgery is usually offered. This depends on your doctor determining that the cataract is the primary reason you are not seeing well. Other causes of poor vision, like Macular degeneration, that would limit the outcome of cataract surgery, should be identified.
How are cataracts treated?
When a cataract is causing bothersome symptoms, it can be surgically removed and replaced with an intraocular lens implant. Because people are living longer, and everyone gets cataracts, cataract surgery has become the most common surgery performed in this country. A lens implant is required because the eye's natural lens has focusing power. The implant has focusing power that compensates for loss of the eye's natural lens. If not replaced, very thick glasses would needed after surgery.
Lens implants have been performed since about the 1950's. Currently the most common materials are Acrylic, Silicone, and Polymethylmethacrylate (or PMMA). There are many lens implant styles from which the surgeon may choose. To read more about various lens implants, click on the "cataract" link above.
How are cataracts removed?
This surgery is performed in a surgery center or hospital, with the eye numbed, and with relaxation medication placed through an IV in your arm, to create as painless and relaxing an experience as possible. Cataracts are removed with an advanced technique called phacoemulsification.
Will I have to wear glasses after cataract surgery?
Most people will need to wear glasses after cataract surgery.
That being said, it is possible in some cases to greatly reduce dependence on glasses after cataract surgery. This can happen if the power of a person's glasses can be incorporate into the power of the lens implant. That depends on your pre-existing refractive errors, which your doctor can help you to understand. You can read more about refractive errors under the cataract link on the menu bar above.
For people interested in reducing their dependence on glasses after cataract surgery, several new lens implant technologies are available. They are Toric and Multifocal lenses. These are also discussed further under the Cataract link on the menu bar above.
More information about cataracts can be found at the National Eye Institute's website