How Do Glasses Correct Vision?
Our eyes are very important in our lives. Although some people can live without it, living with two eyes with perfect vision will help you work properly and do your daily activities well. For those with eye defects, they are still lucky because eyeglasses are created to correct their vision. But how do glasses correct our vision? As we can see our eyes are attached to our head connected to our brain. How can a glass correct the vision that we hardly can see?
To comprehend more clearly on how eyeglasses work in correcting our vision, we need to understand first how our eyes work. Then we can discuss what the functions of eyeglasses are. And lastly we can state how the glasses work.
How Our Eyes Work?
To understand more clearly, the eyes has seven parts: the cornea, sclera, iris, pupil, lens, retina and the optic nerve. The cornea is the transparent coating of our eye covering the iris and the pupil. It is responsible for the refraction and it helps in giving focus for the eye. The sclera is the white part of the eye responsible for the movement of the eyes. The iris is the colored part of the eye with a tiny hole in its center called the pupil. It is responsible in controlling the quantity of light by increasing or decreasing the size of the pupil. If we can notice, when we turn off the lights, our pupils gets bigger because it increases its size to allow more light in our eyes, and it returns to its normal size when the lights are on. The lens which is located at the back of the iris and pupil is responsible in focusing the light to the retina which is located at the back of the iris and pupil. The lens which is located between the iris and the retina is responsible for refracting the image to the retina from the iris in an upside down position. The retina will then convert the light from the lens to the optic nerve and send the nerve impulses to the brain thru the optic nerve. The optic nerve is an important part of the eye because it sends signals to the brain which then converts signals to images. Without the optic nerve we cannot see things.
Functions of the Eyeglasses
At first, eyeglasses are created to correct our vision. But later on, it became a safety gear for many against the light of sun by wearing tinted eyeglasses. It also serves as fashion since many designs of eyeglasses are introduced in the market.
The main purpose of the eyeglasses, which is to correct vision, includes correcting eye disorders such as nearsightedness, farsightedness and astigmatism. With nearsightedness or myopia, distant things cannot be seen clearly because the light directs in front of the retina. Nearsighted individuals cannot see distant things because the cornea of the eye maybe too pointed that it focused light too much. Those with farsightedness or hypermetropia cannot see things that are near because the lights directs behind the retina. This is caused because the cornea is too flat that it cannot direct light well. Astigmatism of the other hand is the uneven direct of light in the eyes.
How the Glasses Work?
After knowing how the eyes work and what do eyeglasses functions are, we can now have a clear understanding on how glasses can correct vision. Eyeglasses has lens to focus the light in the right direction, not in the front of retina, neither behind it. The lens of the eyeglasses depends on what type of eye disorder you have, concave for nearsightedness and convex for the farsightedness. Concave lens gets thinner from the edges to the middle of the lens, thus, creating a longer focal point for the eyes to see distant objects. Convex lens on the other hand is rounded outward, converging the light to make the focal point shorter so that near objects can be seen clearly.