Information on eye biology

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Eye Biology

Eye biology introduction

The eye is a complex structure that works the best when all parts are functioning as part of the whole. Without the eye a human being has no sight.

The eye is an orb that is manipulated by attached muscles. The outer layer of the eye is called the sclera. The sclera is thick, white tissues that encases all of the orb except for the opening to the cornea.

Components of the eye

It is inside of the sclera that we find all of the basic components that enable us to see. These essential components of the eye include --

  • Cornea: This is the dome shaped clear anterior section of the eye. It is the center of the eye’s optical power as it contains the largest area of refraction. The cornea has no blood vessels and is separate from the immune system, which is why it can be transplanted from human to human. It is also contains thousands of nerve endings. The cornea is kept clean by the tears we secrete.
  • Pupil: The pupil is a black hole in the center of the cornea. It allows light to enter the eye. The pupil expands and contracts to control the amount of light entering the eye just like the shutter of a camera. If it malfunctions then vision can dim or become blurry.
  • Iris: This is the colored part of the eye. Pigment in this part of your eye determines its color. Muscles in the iris part of the eye manipulate the size of the pupil.
  • Lens: The actual corneal lens is located inside the cornea and helps to focus light so that the brain can read images.
  • Eye chambers: The lens separates two chambers of the eye. k. The front chamber contains a watery fluid called the aqueous humor and rear chamber consists of a jelly like substance called the vitreous humor.
  • Choroid: The sclera is lined inside by a serious of pigmented membranes. These striations of color are known as the choroids.
  • Retina: In the rear chamber of the eyeball the choroid is lined by a transparent retina. The retina is similar to film in that it helps register the imprint of an image once it is perceived by the lense of the eye. The retina possesses millions photoreceptor cells, called rods and cones. These receptors that are connected to the brain by optic nerves and help perceive colors and shadows.

Protective Components

The eye is also equipped with all kinds of different ways to protect itself from damage. The eyelids and eyelashes prevent foreign objects like dust from falling into the eyes. The eyelids also act like windshield wiper and help smear tears across the eye to cleanse it. Tears are a saline fluid that is produced by the lacrimal glands situated just under the upper eyelids

Tears also produce a thin film over the eye to keep it lubricated. The tears must be kept moist in order to keep the cornea transparent and free from infection.

Orbit of the Eye

The boney structure that contains the organ of the eye is called the orbit. The orbit serves the dual function of protecting the eye and allowing it freedom of movement.

Process of vision

Light enters the eye through the pupil. The lens located mid way in the eyeball focuses rays of light using an array of tiny eye muscles called the cilary body. These ciliary muscles allow the lens to change shape so that the light entering the pupil always hits the retina. The photosensitive rods and cones inside the retina absorb the light and convert them into electrical impulses, which are then carried along the optic nerves to the brain where they produce an image. During the process of seeing the eye is always focusing and refocusing so that electrical impulses can be sent to the brain to produce an image.

The image that is produced on the retina is always upside down but the brain ultimately interprets it as being right side up.

Stereoscopic vision

Each human being has two eyes so that things can be viewed in three dimensions. Each eye captures a different view of an object to produce depth of field. Depth of field allows us to gage the distance, depth and size of anything that we are viewing.

Sight is a sense that few people can do without. It is estimated that almost 80% of our learning is facilities through eyesight. Understanding how the eye functions helps you understand how to keep your vision healthy.