Contact lenses, which are supposed to be fitted directly in the eye’s iris and pupil in contact with the cornea (cornea is the tissue who covers the outer visible surface of the eye), are preferred to be worn by some people to correct any vision defects. In other cases, like severe astigmatism or nearsightedness or could be cases following a cataract surgery, contact lenses are more effective, looks better and comfortable than eyeglasses. However, the main reason of their popularity has been cosmetics. Using these cosmetics, they are certainly invisible.
Hard contact lenses are inserted to the eye by suction, a partial vacuum is created, between the outer surface of the eyeball and the inner surface of the contact lens.
Soft plastic contact lenses are commonly hydrophilic (which means literally water-loving) and will adapt cornea’s moisten shape, to which they are inserted. Therefore, they are relatively easily fitted and wearers or patients sometimes experience discomfort adjusting of the soft plastic contact lenses. However, many ophthalmologists usually advise that the soft plastic contact lenses must be sterilized daily.
The soft plastic contact lenses have been proved valuable for treatment of some eye disorders but unfortunately, sometimes lead problems among the wearers, for example, it may tear or scratch. Generally soft plastic contact lenses have been limited for correction of various kinds of farsightedness and nearsightedness.
Another type of contact lenses are extended wear lenses (EWLs), it were introduced during 1970’s. Extended wear lenses are made of soft plastic like the older kind of lenses, but more porous and thinner compare to old ones, and in fact, they could be worn as long as 30 days only. But wearing extended wear lenses for too long has been discovered causes such problem as scarring of the cornea, it develops microcysts during sleep and can sometimes creates bacterial infections of the eye or eyelid, bacteria such as Acanthamoeba keratitis. This can also cause neurovascularization, the growth of the tiny blood vessels than could possibly cloud the eye’s vision and in worst cases it threatens the wearer’s eye sight.
Disposable contact lenses and cosmetic contact lenses appeared in the late 1980’s. It will be worn for a week and then discarded, disposable contact lenses reduce the danger of bacteria called keratitis and other eye infections. However, disposable and cosmetic contact lenses cost about 50 percent more than the regular extended wear lenses. Cosmetic contact lenses will simply change the color of the eyes. Disposable contact lenses should not be worn longer than what is prescribed and cosmetic contact lenses should not be shared to others to prevent the spread of the eye diseases and other eye infections. Wearer’s must thoroughly clean the contact lenses according to instructions given and should immediately seek for medical help if any problems arise.