Aug. 29--A camera with a dirty or cloudy lens takes a bad picture. The lens of
human eye works the same way.
When an eye's lens becomes cloudy, it is often because of a cataract, but,
unlike a camera lens, you can't wipe it off.
"Sooner or later, almost everyone develops a cataract and needs to have
surgery," said Dr. Gerald Negvesky of Pocono Eye Associates, East Stroudsburg.
Cataracts affect more than 22 million Americans age 40 and older. As the
population ages, more than 30 million people in the U.S. are expected to develop
cataracts, according to Prevent Blindness America, a nonprofit organization.
People often experience difficulty driving at night because of the glare from
oncoming car headlights, which leads them to their doctor.
What is a cataract?
"A cataract is simply clouding of the lens in the eye. As the condition
progresses, vision becomes more and more compromised. Cataracts can form in one
or both eyes, but it does not spread from one eye to the other," Negvesky said.
Developing cataracts is most often related to aging, but just as with turning
gray or going bald, people can develop cataracts at any age.
"When an eye is healthy, light travels through the transparent lens to nerve
tissue or the retina located at the back of the eye," he said.
Once the light reaches the retina, it is changed into nerve signals that
transmit a clear image to your brain -- not unlike a digital camera.
The lens is basically made of water and fibers that are a protein, and
sometimes, as the eye ages, the protein crystallizes and clumps together,
forming a cataract and changing the lens from clear to opaque.
"Now, light rays can't pass through the opaque lens as well, and the retina
cannot transmit a good picture," Negvesky said.
Types of cataracts
The three types of common cataracts that Negvesky usually sees are the nuclear,
the cortical and the posterior subcapsular.
"It isn't unusual for patients to have more than one type of cataract at the
same time," he said.
The most common type is the nuclear cataract, which forms in the center of the
lens. This type is usually associated with aging.
At first, the cataract can cause a person to become more nearsighted or
experience a temporary improvement in reading vision, but, Negvesky said,
"eventually as the lens becomes more opaque and dense, the lens turns yellow and
The change in color makes it difficult to see blues and greens, and other colors
appear dull. "After having surgery, patients often remark on how bright the
colors seem," Negvesky said.
Cortical cataracts form at the edges of the lens, Negvesky said.
It usually begins as whitish, wedge-shaped streaks on the outer edge of the
lens' cortex and, "as the cataract progresses, the streaks spread to the center
of the eye's lens, blocking out light and causing a glare," he said.
Subcapsular cataracts occur at the back of the lens.
"Over time, as the cataract increases in size, it becomes more difficult to see,
and vision may become increasingly blurred," he said.
One type, congenital, is uncommon. According to the Mayo Clinic in Scottsdale,
Ariz., the cataract is present at birth or develops during childhood and may be
the result of a mother having contracted an infection during pregnancy.
"If you live long enough, you can't escape (cataracts). That said, there are
things people can do to help keep their eyes healthier," Negvesky said.
Cataracts are a known side effect of diabetes as well as extensive exposure to
sunlight, a previous eye injury or eye surgery, and long-term use of steroid
"Wearing sunglasses to protect the eyes from ultraviolet rays, eating a diet
rich in lutein, omega-3 fatty acids and vitamins C and E, as well as protecting
the eyes when doing certain jobs, are all things that can keep your eyes
healthy," he said.
Eating spinach, an excellent source of lutein, a carotenoid compound that is
found in colorful fruits and vegetables, can help protect cells from damage,
according to the American Academy of Ophthalmology, San Francisco.
Omega-3 is present in both plant foods and fish. Sardines, salmon, flax seeds
and walnuts are excellent food sources of omega-3 fatty acids, but there are
many other good sources, Negvesky said.
"Having healthy eating habits and a healthy lifestyle may slow the progression
of cataracts and definitely contribute to a better quality of life as you age,"
Prevent Blindness America: preventblindness.org
American Optometric Association: aoa.org
Centers for Disease Control and Prevention: cdc.gov
Mayo Clinic: mayoclinic.com
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