Contact lenses
Contact Lenses
Contact lenses (/ˈkɒntækt ˌlɛnz/), also known as contacts, are thin lenses placed directly on the surface of the eye. They are ocular prosthetic devices used by over 150 million people worldwide, and they can be worn to correct vision, 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 term was first used in the early 20th century.
Types
There are two main types of contact lenses: soft lenses and rigid gas permeable lenses. Soft lenses are made from hydrophilic plastics that contain water, while rigid gas permeable lenses are made from silicone, fluoropolymers, or acrylic glass.
Usage
Contact lenses are used to correct various forms of vision impairment such as myopia, hypermetropia, astigmatism, and presbyopia. They can also be used for cosmetic purposes to change the appearance of the eye, or for therapeutic reasons in the treatment of conditions such as keratoconus or dry eyes.
Care
Proper care of contact lenses is essential to maintain eye health. This includes cleaning and disinfecting lenses regularly, replacing them as recommended by an optometrist, and avoiding wearing them while sleeping or swimming.
Risks
While contact lenses are generally safe, they do carry a risk of eye infection if not properly cared for. Other potential risks include corneal abrasion, allergic reactions, and eye dryness.
History
The concept of contact lenses was first proposed by Leonardo da Vinci in 1508, but the first successful contact lenses were not produced until the late 19th century.
External links
- Medical encyclopedia article on Contact lenses
- Wikipedia's article - Contact lenses
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