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Although contact lenses for more than 100 years, contacts have modern plastic instead of glass, were introduced in 1948. They are worn directly on the cornea of the eye and if it is installed properly, can lead at times almost natural.
The first plastic lenses were made of hard plastic PMMA (polymethylmethacrylate) and do not provide oxygen to the cornea. In the year 1971 were imported soft contacts. Soft lenses are made of a water-loving or hydrophilic polymercan bind up to 74 percent water. Soft contact lenses quickly replaced rigid in popularity, because they are usually more comfortable for the wearer.
Silicone hydrogel lenses entered the market in 1999, and is the world's fastest growing segment in contact lenses. The material is resistant to drying and allows a high transfer oxygen to the eyes. Contact lenses are a medical device, and as such must be prescribed and properly fitted with an eye carePractitioners. You are on the basis of the material are made to endure the length of that group the frequency of disposal and the design of the lenses.
Until the introduction of extended wear contact lenses during the year 1979, all the necessary contacts will be expanded and cleaned at night. Today, members of an extended wear lens for the eye that are worn overnight to seven days without requiring the removal of a continuous lens wear, which can be as long as 30 days to be worn without removal, and slow Daily wear, whichmust be removed every night.
The main disadvantage of contact lenses is that proteins and lipids, which are naturally found in tears at their surface, making it vulnerable to natural disasters such as deposits of calcium. Eye discomfort and dryness can consist of activities to create a water-rejecting film on the front of the lens. Deposits may also be a source of food for an infection-causing bacteria. This makes it particularly important to follow the advice of an eyeMedical and nursing care for replacement. The main function of a contact lens is a problem of vision, has been prescribed to correct the address. Ophthalmologists need to work on an objective which is actually the patient's eye is located, may, taking into account the patient's illness, the other eye, such as dry eyes.
Contact lenses are available in various designs – spherical, astigmatism (toric), bifocal, multifocal, keratoconus and Orthokeratology. Spherical lenses have roundedCorrect shape and myopia (nearsightedness) and hyperopia (farsightedness). Astigmatic or toric lenses to correct for astigmatism, in particular, but also for myopia and hyperopia, astigmatism, as can occur in both states. Bifocals are two different zones for near and far. Multifocal lenses contain different zones to provide near, intermediate and distant vision, a combination that translates into very clear vision. Keratoconus lenses are specially designed to correctirregularly shaped cornea that distorts vision of lead. Only these objectives can place the irregularity and provide a clear solution and comfortable. Orthokeratology lenses are designed to reshape the cornea while the wearer, so slow that they are free during the day. In the United States, one in five people who have to carry the vision correction lenses. Because contact lenses worn directly on the cornea, carriers generally is more favorable than that foundGlasses.
5 Reasons for contact lenses:
2) The bearer of contact lenses can see that the quality of vision appears more natural. This advantage is especially important in sports and during the trip, when the peripheral vision and depth of field states is necessary.
3) contact lenses offer vision that is free of obstacles and annoying reflections.
4) Do not fog lenses with different environmental temperatures, but they represent a constant adjustment, aswith glasses.
5) While the majority of contact lenses are worn for vision correction, there are no lenses are produced and distributed as cosmetic and therapeutic lenses. The cosmetic use is probably the most common. The carrier may improve the color or choose an opaque color contact lenses to suit their mood or wardrobe. Although the colored contact lenses can be made available to those who are not necessarily required corrective measures vision, a valid prescription for allType of contact lenses.
If you experience symptoms or side effects of wearing contact lenses should immediately contact their doctor eye care. For more information on contact lenses and eye care Contact Lens King's disposal.
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