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Cataracts
Cataracts typically develop with age. Over 20 million Americans over age
40 have cataracts. Fortunately, with the excellent advances made in
cataract treatment and surgery, they are one of the most curable vision
problems today. Over a million Americans undergo
cataract surgery
annually.
Although age is the most likely cause of cataracts, it is not the only
reason why cataracts develop. An individual can be born with cataracts or
can develop them early in life. These cataracts are typically called
congenital cataracts.
What are Cataracts?
Cataracts refer to the clouding of the lenses in the eyes. They typically
affect distance vision and cause difficulties related to glare. They cause
vision problems relating to driving, reading and facial recognition.
Cataracts are usually painless and are typically related to the natural
aging process.
As an individual ages, some clouding of the lenses in the eyes is normal.
Cataracts develop over time, and will eventually interfere with vision. In
the early stages, increased lighting and better eyeglasses or contact
lenses can offer effective management. However, as they progress,
cataracts increasingly impact clear vision and can usually be successfully
treated with cataract surgery.
The lens of the eye is situated behind the iris and pupil. As light enters
the eye, it passes through the cornea and pupil to the lens, where light
is focused so as to produce clear images onto the retina. The clouding of
the lens caused by cataracts interferes with the passage of light onto the
retina, causing blurred vision.
The lenses in the eyes are primarily water and protein fibers. The protein
fibers of the lens are situated such that light can easily pass through
unobstructed. With age, lenses become more rigid, thicker and less
transparent. The composition of the lens changes, causing protein fibers
to break down and often clump together. This clouds areas of the lens and
with the development of cataracts, leads to a larger, more dense clouded
area. Why the lenses change with age is unclear; however, researchers
believe that damage caused by UV light, free radicals and general wear and
tear are likely responsible.
Cataracts can form in any of the three layers of
the lens, and occur in three types.
1) Nuclear Cataracts
This is the most common kind of cataract and occurs at the center of the
lens. As the lens changes the manner in which light is focused, it can
slowly turn yellow or pale green, and over time can turn brown. This
interferes with the effective focusing of light, causing blurred vision
and nearsightedness.
2) Cortical Cataracts
This type of cataract is common in diabetics, and is the only kind of
cataract linked to over exposure of UV light. Whitish streaks develop on
the outer edge of the lens and as they progress, begin to move toward the
center of the lens. These streaks interfere with the passage of light to
the retina. Near and distant vision can be affected, causing distortions
in the visual field and an inability to focus.
3) Subcapsular Cataracts
These cataracts typically develop at the back of the lens, at the very
point where light passes to the retina. These cataracts are more common in
diabetics and individuals who are nearsighted, have experienced an eye
injury, or who have been treated with corticosteroid drugs. They cause
difficulty reading, impair vision in bright light, and cause glare in
night vision.
Are you at risk?
Because age is the single, most common cause of cataracts, every
individual is at risk. Researchers point out that all individuals over 65
experience some extent of clouding of the lenses. Some other risk factors
have been linked to the development of cataracts.
1) Sex - women are more likely to develop cataracts than men
2) Race - black Americans are more likely to develop cataracts than white
Americans
3) Family history of cataracts
4) Diabetes
5) Eye surgery
6) Eye injury
7) Prolonged treatment with corticosteroids
8) Smoking
9) Exposure to UV light
10) Exposure to radiation
11) High consumption of alcohol
The existence of free radicals in the body, including the eyes, is one
element that researchers believe contributes to the development of
cataracts. For this reason, excessive alcohol consumption, excessive
exposure to UV light, and excessive alcohol consumption are important risk
factors.
Diagnosing Cataracts
A doctor will diagnose cataracts during a comprehensive eye exam.
Typically, three tests will determine if cataracts are present.
1) Visual Acuity Test
This is the eye test that most of us are familiar with. By testing vision
using a letter chart across the room, a doctor can determine how acute, or
sharp, vision is.
2) Slit-lamp Test
A microscope with an intense, slit line of light illuminates the lens,
cornea and iris, allowing a doctor to see these structures and any
abnormalities that exist.
3) Retinal Exam
In this exam, drops are put into a patients eye that cause pupil dilation,
allowing a doctor to see into the back of the eye. This allows the doctor
to see the extent of clouding present on the lens, as well as any other
abnormalities of the retina and optic nerve.
The treatment of cataracts has become increasingly effective. Advances
made in cataract removal through surgery has led to increased success in
minimizing the vision loss caused by cataracts.
Resources: Get the facts about
cataracts and cataract surgery. Learn
about recent
cataracts research developments.
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