What are Cataracts?
Cataracts are changes in clarity of the natural lens inside the eye that over time impairs the quality of an individuals vision. The natural lens lies behind the iris, in the area of the pupil, which cannot be directly seen with the bare eye unless it becomes extremely cloudy. The lens plays a crucial role in focusing unimpeded light on the retina at the back of the eye. The retina transforms the light to neurological signals that the brain then interprets as vision. Significant cataracts block and distort the light passing through the lens, causing visual symptoms and complaints.
The name cataract found its derivation from the Greek word cataractos, a word that describes rapidly running water. When water becomes turbulent, it is transformed from a clear medium to white, milky or cloudy one. Greek observers noticed changes that seemed similar in the eye and thus attributed visual loss from cataracts as an accumulation of this turbulent fluid. They came to this conclusion having no knowledge of the anatomy of the eye or the function or importance of the lens.
Cataract development is usually a quite gradual process of normal aging but can occasionally occur rapidly. Many people are unaware that they have cataracts because these changes in their vision have developed so gradually. Cataracts commonly affect both eyes, but it is not uncommon for cataracts in one eye to advance more rapidly than in the other. Cataracts are all too common, affecting roughly 60% of people over the age of 60 with over 1.5 million cataract surgeries being performed just in the United States each year.
When people develop cataracts, they begin to have difficulty performing the activities they need to do for normal daily living or for basic enjoyment. Some of the most common complaints include difficulty in driving at night, reading, participating in sports such as tennis, or traveling in unfamiliar areas. Basically all activities for which clear vision is essential. The lens is made mostly of water and protein and certain proteins within the lens are responsible for maintaining its clarity. As individuals advance in years the structures of these lens proteins are altered, ultimately leading to a gradual clouding of the lens.
Factors that may lead to the development of cataracts at an earlier age include excessive ultraviolet-light exposure, diabetes, smoking, or the use of certain medications, such as oral, topical, or inhaled steroids. Other medications that are more weakly associated with cataracts include the long-term use of statins and phenothiazines. Cataracts are rarely present at birth or in early childhood, but as a result of hereditary enzyme defects, and severe trauma to the eye, eye surgery, or intraocular inflammation can also cause cataracts to occur earlier in life. Cataracts that occur at birth or during the first year of life are termed congenital or infantile cataracts. These cataracts require prompt attention with surgical correction or they can prevent the vision in the affected eye from developing normally.
Having cataracts is often compared to looking through a fogged windshield, a window with a dirty film on it or through the dirty lens of a camera. Cataracts may cause a variety of changes in an individuals vision including blurring, difficulty with glare such as with bright sun or automobile headlights while driving at night, dulled color vision where colors may seem washed out or faded, increased nearsightedness accompanied by frequently needing changes in eyeglass prescriptions and occasionally double vision in one eye. Some people notice a phenomenon called second sight in which one’s reading vision improves as a result of their increased nearsightedness from swelling of the cataract. A change in glasses may help initially once vision begins to change from cataracts, but as cataracts continue to progress and opacify the vision becomes cloudy and stronger glasses or different contact lenses will no longer improve the individuals sight.
cataract development is generally gradual and is usually not painful. They are not associated with any eye redness or other symptoms unless they have become extremely advanced. Rapid and/or painful changes in vision are suspicious for other eye diseases and should always be evaluated by an eye-care professional.
Most cataracts are related to aging, although there are other types of cataract:
- Secondary cataract. Cataracts can form after surgery performed for other eye problems, such as glaucoma. Cataracts also can develop in people who have other health problems, such as diabetes. Cataracts are sometimes linked to steroid use.
- Traumatic cataract. Cataracts can develop after an eye injury and possibly years later.
- Congenital cataract. 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 cataract. Cataracts can develop after exposure to some types of radiation.
Many researchers suspect that there are several causes of cataracts, such as smoking and diabetes. Or, it may be that the protein in the lens just changes from the wear and tear it takes over the years. But, whatever the cause it is prudent to pay attention to any changes in your vision and seek a remedy before the condition worsens.