Vision Care

The Functioning of the Human Eye

Wearing spectacles or contact lenses become necessary when something goes wrong with your visual system. Although the functioning of your visual system appears to be a simple function, it is in fact a complex function that involves many but well synchronized activities of different parts of your eye.

In the human eye, the opening designed to let the light in, either through the contact lens or directly, is known as pupil. This pupil is guarded on the outside by a tissue called the cornea. The colored part of the eye surrounding the pupil is known as the iris and this area contains some muscles. Because these muscles can control the pupil, the pupil can widen or constrict to control the amount of light that is let in, whether a person is wearing contact lenses or not.

Behind the pupil is the lens of the eye, which has a function similar to contact lenses or an ordinary magnifying glass. An ordinary magnifying glass is not flexible and so cannot change its focal point. The human eye, unlike a contact lens, has got some muscles that can adjust the lens. So, with the help of the muscles, the focal point of the lens inside the eye can be changed.

There are lots of similarities between a contact lens, and a camera lens. The lens inside the human eye is also very similar to a contact lens. A camera may have two or more lenses. By adjusting the position of these lenses, objects situated at very different distances, near or far, can be brought into the vision of the camera. Something similar to this can be managed by the lens within the eye. It is manipulated by the muscles to ensure that the light is focused on to the retina.

When there are no eye problems, the light rays fall directly on the retina, and there is no need of contact lenses. And when there is an eye problem, glasses or contact lenses are used to direct the rays to the retina. Retina is the all important center of vision. The central part of the retina known as macula is rich in cells known as cones which are responsible for sharp, clear, and colored vision. Another type of retinal cells are rods which help in vision in dim light and also help in peripheral vision. There are about 7 million cones and 100 million rods in the human eye.

When light passes into the eye through contact lenses or without contact lenses, it lands on the retina. When these light rays interact with the retinal cells, certain chemical reactions take place. These chemical reactions kindle the optic nerve, which in turn produce the electrical impulses which eventually get transmitted to the brain. The messages from the eye go to a part of the brain known as visual cortex which registers the image that we are looking at.

When these interconnected actions take place correctly, there would be no need for contact lenses. But if either of these bits malfunctions, you may need a contact lens, and so might have to buy contact lens.