Contact
Lense History...
Contact lenses are
mostly used to correct refractive errors
including nearsightedness, farsightedness, and
astigmatism. These are conditions in which images
are not focused properly on the retina (located
in the back of the eye) and, therefore, cannot be
relayed clearly to the brain).
Contact lenses are also used to manage diseases
of the cornea, conjunctiva, or lids. Contact
lenses adhere to the film of tears that covers
the front of the eye. Each time the eyelid
blinks, it passes over the lens and causes it to
move slightly. This motion allows fresh tears to
flow under the lenses providing necessary
lubrication and oxygen to the cornea.
Types Of Contact Lenses:
The first contact lenses developed in the 1950s
were hard plastic lenses that fit over the
cornea. Because these lenses did not let adequate
oxygen into the eye, there were problems with
swelling, redness, blurry vision, and general
discomfort. Although there are still about 1
million people in the U.S. wearing them, most eye
doctors no longer prescribe them because newer,
easier-to-wear lenses are now available.
The two types of contact lenses most often used
today are soft lenses and rigid gas permeable
(RGP) lenses:
Soft lenses came on the market in 1970, and now
about 80 percent of American contact lens wearers
use them. Their "softness" comes from
the amount of water that the lenses contain, and
they feel pliable rather than hard. Because they
provide more oxygen to the eye, people usually
find them comfortable right away. They are less
likely to pop out during strenuous activity, and
it is harder for foreign particles to get behind
them than behind rigid lenses.
RGP lenses became available in 1979 and are now
used by about 15 percent of contact lens wearers.
They are hard lenses that let in at least as much
oxygen as do soft lenses. They usually give
superior vision (especially when someone has
astigmatism) are easier to care for and usually
last much longer.
In addition to these basic lenses, new types have
been added over the past several years. One of
these is extended wear lenses, either soft or
RGP, that can be worn continuously for up to six
days. Presently over 4 million people wear them.
These lenses are obviously more convenient, but
there are concerns about people overwearing them,
not removing or cleaning them as instructed, and
not seeking follow-up care.
Disposable soft lenses arrived on the market
several years ago - lenses that can be worn for
up to two weeks and then thrown away. Not only
are they convenient, but they do not have much
chance to get dirty, which makes them clean and
comfortable and eliminates many of the worries
about infection that come from extended wear. Not
surprisingly, they are more expensive. If you add
up costs of cleaning supplies and replacements
for other types of lenses, the expense may not be
so different.
Tinted soft lenses, which actually can change the
appearance of the color of your eyes, have become
a hot fashion item. There are several types -
some that change the color of light-colored eyes,
others that color brown eyes. These lenses tend
to be expensive.
Problems Associated With Contact Lenses:
Contact lens wearers can encounter problems with
their lenses. A small group may be unable to wear
contact lenses at all because of hypersensitivity
(for example, some hay-fever sufferers and very
fair-skinned people), difficult optical
requirements, or personal hygiene habits.
Lenses can irritate the eye because of dryness
due to problems with tear production, which may
be inadequate, especially in older people. The
major risk from contact lens wear is corneal
ulceration, which is a potentially blinding
condition. Among the contact lens wearers in the
U.S., there are an estimated 12,000 corneal
ulcers per year.
With hard plastic contact lenses, abrasion of the
cornea can occur because of too rapid buildup of
wearing time during the adaptation period,
particularly with a tight-fitting lens. Wearing
the contact lens too many hours per day can cause
the same problem. Symptoms are pain and tearing.
With patching and/or antibiotics applied to the
eye, symptoms usually clear up within 24 hours.
A common problem that sometimes occurs with soft
lenses is that people develop sensitivity of the
eyes and lids, either to the maintenance
solutions or to mucus forming on the lens surface
itself. Symptoms include decreased lens movement,
increased mucus, and redness of the conjunctiva.
The person generally must stop wearing contact
lenses for several months and then start again
with new lenses and a different type of
maintenance solution.
Soft lenses present a greater risk of corneal
ulcers due to extended wear. The risk may be as
high as 8 times that of daily wear lenses.
Disposable lenses do not overcome the risk of
corneal ulceration.
The wearing of contact lenses should be stopped
if the eyes become red or infected, if vision is
blurred, or if the lenses become uncomfortable.
If symptoms do not resolve, immediate
ophthalmologic care should be sought.
Tips On Care Of Contact Lenses:
Wash your hands with soap before touching your
lenses; avoid soaps with eye-irritating beeswax
or lanolin.
Mucus, tear proteins and environmental pollutants
can build up on your lenses; ask your eye doctor
about the best daily cleaner for your type of
lenses.
Many doctors recommend that you disinfect all
lens types daily with a heat, chemical, or
hydrogen peroxide system.
Use an enzymatic cleaner weekly to remove residue
your daily cleaner missed.
Always store your lenses clean; rinse your lens
case and let it air dry.
Buy small, instead of large, containers of lens
care products; small containers are more quickly
emptied and thus less likely to get contaminated.
Apply eye make-up after putting your lenses in
your eyes.
Use hair sprays, perfumes, and spray deodorants
in another room before you insert lenses.
Check your eyes every morning for redness or
unusual mucus at the edges; pain, watery eyes,
sensitivity to light or blurry vision are signals
to call the doctor.
Remove lenses at once when your eyes become red
or irritated; always carry your glasses with you.
Questions To Ask Your Doctor About Contact
Lenses:
Are there any side effects or drawbacks to
wearing contacts?
What are the chances of developing an infection
from wearing lenses?
What is the risk of corneal ulceration?
What type of contact lenses do you recommend?
What is the best way to clean and care for the
lenses?
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