The Construction and Characteristics of Contact Lenses

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By Carter McIntosh


People make the choice to wear contact lenses rather than eyeglasses for a variety of reasons. For some, vanity is the guiding influence, while others don't care for the weight of the glasses as they rest on the face. Still others prefer to use eye care products that can't be as easily broken. Loss, too, is a consideration, since most people don't remove their contact lenses and put them aside when they're away from the home environment, whereas glasses have often been removed and inadvertently left on a table or some other handy surface.


There are a few basic types of contact lenses which are available to the public, the first of which is the hard contact lens. These are made from a strong polymer plastic and are easy to keep clean since they don't absorb foreign material from either the eye or the environment. As a result of the firmness of the product, however, they can take time to adjust to and shouldn't be left in the eyes overnight. This will cause the cornea to become oxygen deprived - and the cornea needs oxygen flow to remain healthy. Vision is usually crisper with this type of contact lens, as opposed to the softer variety of lenses.

Another common type is the soft contact lens. These are made from a softer plastic - called hydrogel - which makes them more comfortable to wear, but are less durable than those of the hard lens line. The water content in soft contact lenses is higher than that of the hard lens - from 25% to 79% - allowing a better flow of oxygen to the cornea. Due to the fact that the material is highly porous, infections and eye irritation are more common. This happens when dust, protein and bacteria cause contamination of the lenses, which are pressed against the surface of the cornea.

Gas permeable contact lenses are more rigid than the soft lenses, but are made of the type of plastic that allows oxygen to reach the cornea and are easier to take care of, insert and remove than the softer version. This type of contact lens correct most vision problems and are now approved for extended wear.

Due to the nature of contact lenses and the fact that they cover a portion of the eye, there are specific care instructions that should be heeded, regardless of the type of material from which they're constructed. In addition to washing and drying your hands before handling contact lenses, you should also be sure to insert and remove them correctly; only apply make-up (carefully) after contacts have been inserted; use the specific solutions that your doctor has recommended; avoid rubbing your eyes while contact lenses are being worn; don't place your contact lenses on a warm surface, since they may melt; avoid wearing contacts when under a hair dryer or around harsh chemical fumes; don't use saliva to moisten contacts for insertion; and avoid inserting contact lenses without disinfecting them. These and many other guidelines will keep your eyes healthy and prolong the life of your contacts.

About the author:
Carter McIntosh is a writer and contributing author to 101 Contact Lenses. Learn more about contacts and lasik eye surgery at http://www.101-contact-lenses.com

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