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Over
24 million people in the United States now wear contact
lenses.
Contacts
provide a safe and effective way to correct vision
when used with care and proper supervision.
They can offer a good alternative to eyeglasses,
depending on your eyes and your lifestyle.
What are contact lenses?
Contact lenses are thin, curved plastic
disks designed to cover the cornea, the clear front covering
of the eye. Contacts cling to the film of tears over the cornea
because of surface tension, the same force
that causes a drop of water to cling to the side of a glass.
Contact lenses are used to correct
the same conditions that eyeglasses correct:
- Myopia (nearsightedness)
- Hyperopia (farsightedness)
- Astigmatism(distorted vision)
- Presbyopia (need for bifocals)
Special tinted contacts can be used to
change the color of the eyes to various degrees. Contact lenses
are sometimes used therapeutically in eye diseases
where an uneven cornea blurs vision, such as keratoconus or
scarring.
What types of contact lenses are available?
RIGID lenses
Rigid contacts were the first lenses;
they were developed in the 1960s. They are made of a type
of plastic called PMMA, which is very durable, but does not
allow oxygen in the air to directly reach the cornea.
When the eye blinks, the lens moves, which
allows the oxygen dissolved in the tears to reach the cornea.
While rigid lenses are probably the least comfortable type
of contacts to wear, some users prefer them for their durability
and lower cost.
RIGID LENSES TABLE
Gas-permeable lenses
Newer rigid lenses made of plastics combined
with other materials, such as silicone and fluoropolymers,
allow oxygen in the air to pass directly through the lens.
They are called gas permeable.
Gas-permeable lenses are less durable
than conventional rigid lenses but are more comfortable. Some
gas-permeable lenses are extended wear, and may be worn overnight
for up to seven days.
Soft contact lenses
These lenses are made of plastic materials
that incorporate water. The water makes them soft and flexible,
as well as allowing oxygen to reach the cornea.
SOFT LENSES TABLE
More than 75% of contact lens wearers
in the United States use soft lenses. Some soft contact lenses
are extended wear lenses, which means they are designed to
be left in the eye overnight. It is recommended that extended-wear
lenses be removed weekly, at a minimum, for thorough cleaning
and disinfection.
Soft daily-wear lenses should never be
used as extended-wear lenses. Extended wear lenses can be
used as daily-wear lenses.
Disposable soft
contact lenses
Disposable lenses for daily or extended
wear have recently become available. The lenses are discarded
and replaced each week. These lenses are convenient and may
reduce the chance of allergic reactions and deposit formation.
Toric contact lenses
Toric lenses correct moderate astigmatism.
They are available in both rigid and soft materials.
What does the price include?
When comparing the price of contact lenses,
it's important to consider what services are included. Does
the fitting include a thorough eye examination and follow
up? Can you exchange lenses during the initial fitting, and
is insurance for lost lenses available?
If you need treatment for an eye condition
not directly related to the contact lenses, such as inflamed
eyelids or dry eyes, there may be additional charges.
What are the risks of wearing contact lenses?
Rigid lenses that are not gas permeable
are more likely to scratch the cornea if the lens does not
fit properly or if the lens is worn while sleeping. They are
also more likely to slide off the cornea and become hidden
under the lid.
Rigid lenses traditionally had a reputation
for "popping out" of the eye. New lens designs have
minimized the chance of losing a contact even during vigorous
exercise.
Rigid gas-permeable lenses may allow more
protein build-up than rigid nongas-permeable lenses. Protein
build-up results in discomfort, blurring and intolerance to
the lenses. You will need special cleaning solutions to dissolve
the protein.
Daily-wear lenses should never be worn
as extended-wear lenses. Misuse can lead to temporary and
even permanent damage to the cornea. People who wear
any type of lens overnight have a greater chance of developing
infections of the cornea. These infections are often due to
poor cleaning and lens care.
What is proper care of contact lenses?
Contact lenses must be properly cleaned
and disinfected when you remove them to kill germs and prevent
infections. At the time you insert your contact lenses, you
should thoroughly rinse the case with warm water and allow
it to dry. All contact lens cases need frequent cleaning,
including disposable lens cases.
Soft extended-wear contacts are the most
likely to have protein build-up and cause lens-related allergies.
Soft daily wear lenses are less likely to create problems.
Rigid gas-permeable or disposable lenses may be good choices
for someone with allergies.
Homemade saline solutions have been linked
to serious eye infections and should never be used. Any eye
drops, even nonprescription ones, can interact with all types
of contact lenses. Check with your ophthalmologist
before you use any eye drops.
Who should not wear contact lenses?
Most people who need vision correction
can wear contact lenses, but there are some exceptions.
Some of the conditions that might keep
you from wearing contact lenses are:
- Frequent eye infections
- Severe allergies
- Dry eye (improper tear film)
- A work environment that is very dusty
or dirty
- Inability to handle and care for the
lenses properly
The health of your eyes should be your
main concern. An ophthalmologist is the physician specialist
who can help you decide whether contact lenses are right for
you.
Are contacts for you?
Whether or not contact lenses are a
good choice for you depends on:
Choosing an eye care professional who
is knowledgeable and experienced with contact lenses, and
with whom you can discuss your needs and expectations
Diagnosis and treatment of conditions
that may prevent contact lens wear
Your personal motivation to make it through
a period of adjusting to your contact lenses
Adhering to contact lens guidelines for
wear, disinfecting and cleaning
If you have any additional questions
or would like further information, ask your ophthalmologist.
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