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More than 34 million Americans wear contact lenses.
There are three types of contact lenses:
Soft lenses, the most common type of contact lens, were first introduced
in 1971; Oxygen permeables, and Hard (PMMA) lenses, which
are the original type of contact lens and are now obsolete.
Oxygen permeable contact lenses are commonly known in the
vision care field as rigid gas permeables, or RGPs. Your eye doctor will
probably call them RGPs.
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Soft Contact Lenses
Today's soft contact lenses have wonderful characteristics. Many soft lenses
can be stretched but are durable and have a memory to return to their original
size and shape. This lens is tolerated in a size larger than the cornea. For
optimum centering and stability. Its large size lying under the eyelid margins
permits the lid margin to glide over its surface without impairing on the edges
of the lens. This is one of the secrets of soft lens comfort. The softness of
the lens permits the lens to contour itself to the shape of the eye.
Soft Lenses have a very small pore structure with a variation in the size of
the small opening. These pores are so small that they do not permit the larger
molecules of bacteria or fungi to penetrate an intact lens.
The soft lens does not require a rigid daily wear schedule. The individual can
choose to wear the lens only at certain times, such as during the evening or on
holidays.
Because of the large size and minimal movement of soft lenses, lens loss is
reduced considerably. The lens is not ejected by a blink because the lid margin
does not touch the edge. The lens loss is further minimized on lens removal
because one has to pinch and hold the lens rather than pop it out, as in the
removal of a rigid lens. The soft lens is difficult to dislodge and makes an
ideal sports lens.
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Oxygen permeables
Many people are still unfamiliar with oxygen permeable contact lenses.
Oxygen permeables are made of a firm, durable plastic that transmits oxygen.
They offer excellent eye health: because they don't contain water, they resist
deposits and are less likely than soft contacts to harbor bacteria. Oxygen
permeable lenses clean and disinfect easily, don't dehydrate, and last longer
than soft lenses -- often many years longer. |

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