Contact lens
Contact Lens
A Contact Lens (pronounced: /ˈkɒntækt lɛnz/) is a thin lens placed directly on the surface of the eye. Contact lenses are considered medical devices and can be worn to correct vision, or for cosmetic or therapeutic reasons.
Etymology
The term "contact lens" is derived from the fact that the lens is in direct contact with the eye. The word "contact" comes from the Latin contactus, meaning "touching", and "lens" comes from the Latin lens, meaning "lentil", due to the convex shape of the lens resembling that of a lentil.
Types of Contact Lenses
There are two main types of contact lenses: Soft Contact Lenses and Rigid Gas Permeable (RGP) Contact Lenses. Soft contact lenses are made of soft, flexible plastics that allow oxygen to pass through to the cornea. Rigid gas permeable contact lenses are more durable, resistant to deposit buildup, and generally give a clearer, crisper vision.
Usage
Contact lenses are used to correct the same conditions that Eyeglasses do: Myopia (nearsightedness), Hyperopia (farsightedness), Astigmatism (distorted vision), and Presbyopia (age-related loss of near vision).
Risks and Complications
While contact lenses are generally safe and effective, they are not without risks. Improper use or care of contact lenses can lead to serious eye infections or other complications such as Corneal Ulcers, Corneal Abrasions, and Conjunctivitis.
Related Terms
- Ophthalmology: The branch of medicine that deals with the diagnosis and treatment of eye disorders.
- Optometry: The practice or profession of examining the eyes for visual defects and prescribing corrective lenses.
- Orthokeratology: The use of specially designed contact lenses to reshape the cornea and improve vision.
External links
- Medical encyclopedia article on Contact lens
- Wikipedia's article - Contact lens
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