How Our Eyes Work And How We See - Medico Tribune

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Monday, September 28, 2020

How Our Eyes Work And How We See

 


Everything we see around us is actually light from that object entering the eye. That's why we can't see when we close our eyes or in the dark. When light falls on the eye from an object, it reaches the retina through the reflexes of the eye, such as the cornea, aqueous humor, lens, and vitreous humor.


All of these refractive media, especially lenses, work to focus the incoming light on the retina. In the normal eye, light rays from an object can be seen in the retina and later in the normal way.


The retina of the eye falls backwards or forwards, respectively, in those eyes whose refraction capacity is more or less the same. In these cases, if the necessary power glasses are given in front of the eyes, the light rays fall on the retina and help to see better.


When viewed with the naked eye or with glasses, light rays from an object fall backwards into the retina through the lens. For example, a picture of a standing person falls on the retina in such a way that its head is down and its legs are up. 

The reflection of the object visible in the image has fallen in reverse on the retina


After the light rays fall on the retina, there is a reaction with tiny cells, which are converted into electrical stimuli and these stimuli reach the brain through the optic nerve.


After reaching the center of vision of the brain, we can see the opposite object in a straightforward way. For example, we see a standing man standing.

Nerve impulses from the retina reach the center of vision of the brain through the optic nerve, optic kayasma, optic trust, and so on. If there is any defect in the cornea and lens through the reflexive medium, it is usually seen with the help of glasses.

Before discussing glasses it is necessary to know about the refraction of the eye and its two.


We see with our eyes. Some people look at it with the help of glasses. The relationship between the eyes and the glasses is very close when it comes to vision.


We have two round eyes in the front of our skull. The two eyelids look rectangular but actually round. And the outer covering of this eyeball is made up of three layers and the inside is like Aquas, Vitreous and Lens etc.


The outer layer of the eyeball

This layer is made up of hard, thick and fibrous tissue. The front 1/6 of it is transparent and a convex. Which is called the cornea. Behind this layer 5/6 part i.e. the rest except the cornea is thick, white and opaque which is called sclera.

The cornea is transparent like a watch glass. It usually looks black because it has Irish behind it, but it is completely transparent. Light enters the eye through the cornea and we see.

The diameter of the cornea is 11 mm from the inside of the eye, but the diameter of the cornea from the outside is 12 mm and the top-bottom is 11 mm.

That is why the cornea is not perfectly round but elliptical. This change in normal shape can lead to a change in eye power. In these cases it is possible to see better by using the required cylinder lens.

The cornea tendon does not have blood vessels but has plenty of nerves, so it is very sensitive.







The sclera and the inside of the eyelid are covered with a thin membrane called the conjunctiva.

There are many fine blood vessels in this screen. The rectus muscles of the sclera are attached so that the eyes can be rotated in different directions. The optic nerve exits the back of the sclera.


In addition, four large veins protrude from the inside of the eye through the sclera.

Small and large ciliary arteries around the optic nerve enter the eye.

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