Unlike glasses, which are external to the eyes, a contact lens fits directly to the wearer’s eye. The contact lens is made of plastic and is so shaped that it can totally confirm to the eye. It serves as an external refracting surface. It corrects vision defects like myopia and hypermetropia. Focusing of the eye can be done with such lens in the same manner as with spectacles.
Millions of people in the US use contact lens. Besides correcting vision; this lens is also used for cosmetic and therapeutic reasons.
These lenses can be made from various types of materials of which some are rigid and some are soft. Over the years there have been phenomenal growth of its technology and today this lens is available in a variety of designs and color.
The different designs of contact lens include colored, disposable, astigmatic presbyopic, keratonic and aphakic types.
Such lenses can correct all problems that glasses can, also, some additional ones where glasses are ineffective. They provide better vision to people whose cataracts have been removed and to those who are extremely hypermetropiac. People with damaged cornea find better vision with contact lens. For sportsmen, contact lens gives a better option. Also as compared with glasses, these lenses give better side- vision.
Two main types of lenses are used today. Soft lenses are made of hydrophilic plastic. They absorb liquid and must be maintained moist to keep them soft. Majority of people use these comfortable soft lenses. The second type of contact lens is the gas permeable type. These are rigid and are relatively easy to maintain. The rigid lenses known as RPG are made of durable and flexible plastic and allow oxygen to pass to the cornea through the lens.
To use lenses, advice from an ophthalmologist is imperative. The ophthalmologist should advice whether contact lens fit the person concerned and the type suitable for the person.