3 Layers of Eyes

 

What are Eyes?

The eyes are a great blessing of Allah. it’s the most sensitive part of the body. The eyes are part of the visual system. The eyes detect light and convert it into electrochemical ampoules in neurons. The human eye, a special sensory organ capable of receiving visual images, is then transmitted to the brain.

Structure of eyes

The structure and function of the eyes are complex. Each eye constantly adjusts the amount of light that it receives, focuses on near and far objects, and constantly produces images that are instantly transmitted to the brain.

1. Choroid

A layer of blood vessels that covers the back of the eye and lies between the retina (the sensitive layer of inner light) and the sclera (outer white eye wall).

2. Ciliary Body

The structure that consists of muscles and is located behind the iris, which focuses on the lens.

3. Cornea

A clear frontal window of the eye that transmits light to the eye and focuses Corrective laser surgery changes the shape of the cornea, changes the focus

4. Fovea

The center of the macula provides sharp vision.

5. Iris

The iris is the colored part of the eye that helps regulate the amount of light entering the eye. When there is the bright light, the iris closes the pupil to give off less light. And when there is less light, the iris opens the pupil to give more light

6. Lens

Focuses light rays on the retina. The lens is transparent and can be removed and replaced if necessary. As we age, our spectacles deteriorate, resulting in the need to wear spectacles. Intraocular lenses are used to replace cloudy lenses due to cataracts.

7. Macula

The part of the retina that contains light-sensitive cells. These light-sensitive cells in the macula allow us to see precisely the details in the center of our visual field. Deterioration of the macula with age is a common condition.

8. Optic Nerve

A bundle of over one million nerve fibers that carry visual messages from the retina to the brain. Our brain actually controls what you see, because it combines images. The retina looks at the images upside down but the brain turns the images to the right. This reversal of images that we see is like a mirror in a camera. Glaucoma is one of the most common eye conditions associated with optic nerve damage

9. Pupil

A black center opens in the middle of Iris. The pupil resizes to accommodate the amount of light available. This opening and closing of the light in the nose are mostly similar to the aperture of 35 mm cameras which give more or less light depending on the situation.

10. Retina

Nerve layer in the back of the eye. The retina senses light and produces electrical impulses that are sent to the brain through the optic nerve

11. Sclera

The white outer coat of the eye, around the iris.

12. Vitreous Humor

A cleansing, gelatinous substance that fills the central cavity of the eye.

layers of Eyes

The eyeball is surrounded by a three-layered wall, with three coats of the eye. They are made up of different tissues and perform different functions.

Outer coat

The outer layer of the eye is made up of dense connective tissue, which protects the eye hair and maintains its shape. It is also called a fiber tank. The fibrous tunic consists of the sclera and cornea. The sclera covers almost the entire surface of the eye hair. It is commonly referred to as the “white eye” because of its white outer surface. The sclera provides attachments to the muscles that control eye movement. The transparent cornea occupies the middle part of the front of the outer thumb. It acts as the “window” of the eye, allowing light to enter and bend its rays, thus giving the eye the power to focus more. The front of the sclera, the visible part, and the inner surface of the eyelids are covered with conjunctiva, a mucous membrane that helps lubricate the eye with tears formed by the tear glands, thus drying the eye Protects from.

Middle coat 

The middle layer of tissue around the eye also called the vascular tunic or “uva”, is formed – from front to back – through the choroid, ciliary body, and iris. Its main functions are to supply oxygen and nutrition to the eyes. A black pigment, melanin, is found throughout the choroid to help control uncontrolled reflection inside the eye, resulting in the impression of potentially blurred images.

Inner coat

The third and inner coat of the eye is the retina, which is responsible for the perception of images. The retina is a light-sensitive layer of nerve tissue that consists of numerous sensory cells, so-called light or photoreceptor cells, as well as connected nerve cells and other types of cells, all working together to make a person be seen. For vision, there are two types of photoreceptor cells: rods and cones. The bars give the impression of a black and white vision, mostly in dim light, while the cones help to see colors in daylight. The light and color impressions received by these photoreceptors are transmitted to the nerve cells attached to the retina, which in turn, send these signals – through the optical nerve – to the visual center of the brain. The point where optic nerve fibers originate from the hair follicle (optical disc) has no photosensitive cells. Thus it is insensitive to light and is called a “blind spot”.Opposite the lens, the retina contains a small yellow part, the “macula lutea”. Its central part (fovea centralis) is filled with conical cells for color perception. At this point, the sense of sight is most accurate and detailed.