Contacts are lenses placed on the eye. They can be for corrective, therapeutic or cosmetic purposes. It is estimated that 125 million people use contacts worldwide.

Leonardo da Vinci is often credited with the first idea of these lenses. Around 1508, he began describing and sketching these ideas, which eventually were printed in the Codex of the Eye, Manual D. In 1801, Thomas Young came up with liquid-filled eyecups. Nearly 80 years later F. E. Muller, a glassblower, produced an eye covering that was tolerable and see through. Inventions by Adolf Gatson, Eugen Fick and Louis J. Girard were similar in structure and more functional than previous eyecups. Not until 1949 would the first corneal contact be developed. Since that time they have steadily evolved.

Corrective contacts improve vision. They are able to focus light on the retina, therefore correcting focus. Generally these contact correct: near or shortsightedness, far or long sightedness, presbyopia and astigmatism. Lenses that are red-tinted can allow colorblind people to distinguish colors better, though it cannot restore normal color vision.

Cosmetic contacts change the appearance of eyes. They can also change the vision. Sometimes called decorative lenses, theses lenses can change eye color and make eyes appear aroused, lifeless, cloudy and demonic. Cosmetic lenses are often utilized in theatre or movie productions.

Non-refractive conditions, such as keratitis, corneal edema, ulcers and erosion, bullous keratopathy and descemetocele can be aided with therapeutic lenses. They can also help with dry eyes. Some therapeutic lenses deliver medicine to troubled areas of the eye. Bandage contacts can protect the eyes. They keep patients from rubbing eyes that have an injured or diseased cornea. Without the constant eye rubbing, the cornea can heal faster.

Lenses used to be made from glass. That material was irritating to the eyes and those lenses were usually not tolerable for more than a couple of hours. Silicone hydrogels is the material used in most contact production today. It is preferred because it is flexible, comfortably, long lasting and oxygen permeable.

A doctor will usually prescribe contacts for a patient. They will also show the patient how to take care of and insert the lenses into the eye. There are daily and extended wear lenses. Daily lenses should be taken out before sleeping. Extended lenses can stay in overnight and for approximately a weak. They are convenient, but can also bring increased risk of eye-conditions developing in the cornea. Before inserting the lens, an individual should thoroughly wash their hands with soap and water and their lenses with proper solution. The lenses should be cleaned and replaced as often as your eye doctor recommends.

Complications can develop if the lenses are not maintained. Ptosis can develop in the eyelid. Superior limbic keratoconjunctivitis and giant papillary conjunctivitis affect the conjunctiva. The cornea can be disrupted by epithelium. Problems can arise in various structures of the eye. If these issues are not properly treated, they can lead to more serious problems. At the first signs of problems, contact your eye doctor. Most of these conditions can heal quickly if they are caught early on.

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