Contact Lenses are thin, artificial lens worn on the surface of the eye to correct refractive defects of vision. There are two basic types of lenses:
Soft lenses: are made of a water absorbing plastic gel for greater flexbiity, which can be worn without removal are for several weeks at a time. soft contact lenses are ususally more comfortable because they allow oxygen to penetrate to the eye's surface. Their large size makes it more dificult to lose than the hard lenses.
Hard lenses: or gas-permeable lenses were introduced, and have a limited wearing time because of potential irritation of the cornea. This type of lenses make up only 10% of the market, because they have better effect on some treatment. Your doctor is the only person that can determine the type of lenses that perfectly fit your eyes.