A contact lens is a thin plastic or glass lens that is fitted
over the cornea of the eye to correct vision problems such as
myopia, hyperopia or astigmatism.
There are two general types of contact lenses--soft and rigid
gas permeable hard lenses. They both have unique benefits and some
may even come with a colored tint, ultraviolet protection or as
bifocals.
Soft lenses
Soft lenses are made of a soft plastic
and are more comfortable than hard lenses because they hold more
water. Many soft contact lenses also provide UV protection. They
are usually disposable and can be thrown away after a short period
of use, generally every two to four weeks or daily, depending on
the type of lens prescribed. Being able to have a fresh pair of
lenses means less chance of infection, less cleaning, and more
comfort, especially for people whose eyes naturally produce more
protein that clouds lenses.
While most people choose soft contact lenses because of their
benefits, there are also some disadvantages. Soft lenses easily
absorb pollutants like lotion or soap from your hands, which can
irritate your eyes. They are also more fragile than hard lenses and
can rip or tear easily.
The most recent type of soft contact lenses to hit the market,
include Daily Disposables and New Silicone Extended Wear
Disposables.
Daily disposables: These contacts are only worn once and
then thrown away. The benefits of Daily Disposables include never
having to clean your contact lenses, convenient replacement
schedule, and reduction of dry eye and irritation related to
contact solutions. If you are an allergy sufferer, these are the
contacts for you.
Silicone extended wear disposables: These are made
with a new material that can be worn for up to 30 nights and days.
The new silicone material also prevents deposit build up and
reduces dry eye irritation.
Rigid gas permeable hard lenses
Rigid gas permeable
lenses, or hard contact lenses, are more rigid than soft lenses and
therefore more durable. Unlike older versions of hard lenses, rigid
gas permeable lenses are made with silicone polymers, allowing
oxygen to circulate to the cornea of the eye. Compared to soft
contact lenses, hard contacts maintain their shape better and offer
clearer vision for some types of corrections. They are also
extremely durable and easy to take care of. However, if you are
considering this type of hard contact lens, you should know
that:
- There is a 10-15 times greater risk of developing corneal
ulcers, a serious infection, which may damage your vision if not
treated.
- Sleeping in extended wear contacts may decrease flow of oxygen
to the cornea, which can damage you vision.
- Undesirable reshaping of the cornea may occur.
- The amount of time needed to adjust to hard contacts is often
repeated after not wearing them for as little as a day. Therefore,
in order to achieve maximum comfort, you have to wear the contact
lenses every day.