The development of the contact lens has changed, to see how people with poor vision of the world. At one time hard lenses were the only contact that anyone had access to, but later came the available soft lens that required less care and could be thrown herself after a certain period of wearing. Now there are many different ways lens carrier on their requests and recommendations of their doctors to contact. This allows more People wear contact lenses than ever before. Many of those who could not wear contacts prior year, because the way that was used was not for them, now they carry with ease.
By their very nature so many types available, the type of contact that is required depends on specific situation of a person. Here are the different types of contact lenses that are available:
PMMA lenses, the so-called hard> Contact lenses are the oldest, are there. Believe it or not, they have been around since the 1960s. They are made of polymethylmethacrylate (PMMA). These contacts are very durable, but their disadvantage is the fact that they do not allow oxygen to reach directly to the cornea. The oxygen is obtained in the cornea, when the wearer blinks and oxygenated tears reach the cornea through the movement of the lens. They are inexpensive, but they are rarely used. However, theresome patients they prefer.
Soft contact lenses are the lenses that are used most frequently. They are made of plastic and other materials such as silicon. Water is also used in the construction, which makes it soft. Moreover, they allow oxygen to reach directly to the cornea. Soft contact lenses are used by 3 / 4 of the contact lens wearers in the United States. There are also various types of soft contacts, such as:
Daily DisposableLenses, which must be thrown away at the end of each day. These are more expensive, but the risk of developing an eye infection is minimal.
Toric lenses for astigmatism. These contacts are for those who have no other issue other than the eye astigmatism, who need to be corrected.
Extended wear lenses take 2-4 weeks. The use of the 30-day contact started about 6 years. The risk of infection is higher and they tend to be somewhatexpensive, but the carrier is able to bear the contacts to day and night for 30 days without removing them.
The last type of contact is the gas-permeable lens. These are the newer version of the hard lens made of silicone and other materials that oxygen can reach directly to the cornea to be made. For this reason they are called gas permeable.
There are so many advantages of using contact lenses for those who are in a position to bear any of the abovehave been described. Of course there are risks such as hard contact lenses are more likely to scratch the cornea and extended wear contact lenses cause infections, especially if they are not properly maintained. No matter what kind of contact helps a person, it is important that they take care of them as they are assumed to minimize the risk of infection in the eye. Those who can not develop common eye infections are allowed to wear them with theirPhysician. Even people with severe allergies may be prohibited, but contacts open up a whole new world for those who can not wear them because they see things differently.
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