|Eyeglasses , spectacles Home|
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Eyeglasses , spectacles or glasses are usually worn for vision correction or protection. Though contact lenses also provide vision correction, many people prefer to wear glasses, since they can be easily worn, are less expensive and easy to maintain. Many people are uncomfortable putting their fingers in their eyes for wearing contact lenses.
Depending on whether the person is suffering from myopia or presbyopia, contact or concave lenses are used. The power of the lens is determined by the optician or eye specialist checking the eye. Eyeglasses normally consist lenses which are placed in front of the eyes and are supported on the bridge of the nose and on the ears by the spectacle frame. The spectacle frame is usually selected according to the shape of the face and can be made from different types of material.
Earlier lenses used in eyeglasses were made from glass which would break easily. They have been replaced by various types of plastics like polycarbonate or CR39, which have similar optical properties. They are also lighter and do not break easily. They usually have a scratch resistant and hydrophobic coating to making cleaning of the lenses easier. Eyeglasses worn for safety purposes - for protection against foreign objects (usually in industrial environments) can also be modified for vision correction.
As people become older, in addition to myopia , they may not be able to see nearby objects, so they may require glasses with multiple focus lenses - bifocal glasses. These eyeglasses have distinct viewing areas for viewing nearby and distant objects. Some people prefer to have different eyeglasses for different activities like watching television or reading newspapers. The most advanced multifocal lenses allow a user to view both distant and nearby objects without any effort by the user of the eyeglasses.
Most users of eyeglasses find them convenient to use, since very little maintenance is required. However, they cannot be used while playing rigorous sports and can trap vapor while walking in the rain.
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