|
Hard Contact Lenses Have Its Own Advantages |
|
|
|
Several types of contact lenses are available
to take care of your eyes including hard contact lenses. There are two
types of hard contact lense. The first one is the conventional hard
(polymethyl methacrylate, or PMMA) lenses that are made of a fairly
stiff plastic. Though they correct vision with no distortion, they are
the least comfortable type of contact lens. The second one is the rigid
gas-permeable (RGP) lenses that are more comfortable than conventional
hard lenses. In fact, some gas-permeable lenses are designed to be worn
overnight and for up to 7 days.
Though hard
contact lenses provide clear vision and last for a fairly long time (5
to 10 years), there are only a small number of hard contact lens
wearers. In fact, the inconvenience that the non-gas permeable lenses do
not allow oxygen to reach the cornea can have bad repercussions which
can lead to major eye damage. Before 1971, every contact lens was made
of PMMA. The advent of gas permeable lenses brought a reprieve from the
PMMA lenses as it allows oxygen to pass through it to the cornea,
resulting in greater comfort.
Rigid gas permeable lenses are more
rigid than soft contact lenses and therefore are more durable. The new
type of rigid gas permeable lenses are made with silicone polymers,
allowing oxygen to circulate to the cornea of the eye. They can be
disposable contact lenses, bifocal contact lenses, colored contact
lenses, cosmetic contact lenses etc. One great advantage of rigid gas
permeable lenses is that unlike soft contact lenses, these lenses
maintain their shape and offer clearer vision for some types of
corrections. You can easily take care of these lenses which are
extremely durable. You only need a good contact lens cleaner for
cleaning these contact lens. The amount of time needed to adjust to
rigid gas permeable contact lenses is longer than the soft contact
lenses. To achieve maximum comfort, a rigid gas permeable contact lens
should be worn every day. There are some rigid gas permeable contact
lens problems.
Rigid gas permeable contact lenses are also
available in extended wear options, meaning you can wear them overnight.
Sleeping in extended wear contacts may decrease the flow of oxygen to
the cornea, so it is important to wear them as directed. As oxygen is
not passed, you can have contact lenses dry eyes. Rigid gas permeable
lenses also provide better deposit resistance than soft contact lenses.
But, because soft lenses are instantly comfortable to wear, they are
more preferred than the gas permeable lenses. Gas permeable lenses
require an adaptation period before they become comfortable. Also, some
people experience "spectacle blur" with gas permeable lenses. When gas
permeable lenses are removed, vision is blurry, even while wearing
glasses. This effect is temporary, but it can necessitate full-time gas
permeable wear. This can make gas permeable an all-or-nothing
proposition, which some people will find inconvenient.
|
