Friday, 18 May 2012

How to Use Contact lenses

Contact lenses are thin transparent plastic discs that are used for vision correction. Contact lenses are just like eyeglasses and they are worn directly on the cornea of the eyes. Contact lenses can rectify at the defects that can or cannot be corrected by regular eye glasses.

Contact lenses stay in place by sticking to the layer of tear fluid which floats on the surface of the eye. They are also hold in place by the eyelid pressure. As the eye blinks, it provides lubrication to the cornea. This helps to flush away any impurities that may have become stuck to the contact lens.

Typically, the light rays must converge at the retina i.e. exactly behind the eye ball, so that we can have a clear vision. However, it does not happen so in both the cases of myopia (near sightedness) and hyper myopia (near sightedness). Contact lenses correct this problem by enabling the light rays to converge at the retina and correct the vision problem.

A person suffering from myopia is prescribed contact lenses which are thicker on the edge and thinner in the middle. Such lenses are called minus or concave.

The concave lens spread the light away from the center of the lens and more focal point of the light forward so as to reach the retina.

A person with farsightedness is prescribed to use lenses that are thicker in the middle and thinner at the edge. These lenses bend the light toward the center and move the focal point back. This enables the light to focus on, rather than behind, the retina. Such lenses are called plus or convex.

A person, in astigmatism, has an irregular shaped cornea. This causes the light to converge at different points in the eye and hence leads to blurry vision. In such cases, the contact lenses are designed so as to give the cornea a proper shape. It helps the light rays to converge at a single focal point at the retina.

Some advantages of contact lenses over spectacles are that contact lenses offer a clearer vision than spectacles. They are closes to natural sight and they move with the eye and correct the error closes to the eye. They can even be tinted to protect against the sun. thus, contact lenses provide a much wide field of vision than the ordinary spectacles.

2 comments:

This conact lenses has a extraordinary and obvious color that it is transparent color. Generally, people want to wear like it. Moreover many people like and buy it including me.

Very nice & useful to about the post of the contact lenses

Post a Comment