Cornea Associates of Texas would like to help you better understand how your eyes work. Through your eyes, you see and interpret colors, dimensions, and the very shapes of the world. Your eyes are able to see in bright light, or for that matter, in dim light. They do this by converting light rays into electrical signals and sending those signals to the brain. The brain interprets these signals as visual images.
Although the eyes are crucial to everything you want to do, whether reading, participating in sports, driving a car, watching a sunset, playing on a beach, or writing a letter, they are often taken for granted. Let’s take a minute to discuss the parts of the eye and how they work together to achieve sight.
There are nine distinct parts of the human eye. They include: the cornea, conjunctiva, iris, pupil, lens, optic nerve, sclera, vitreous, and the retina.
Here are the definitions of these parts:
Cornea
The cornea provides focus when light images enter your eye. There are layers of tissue that make up the cornea. The outer surface is the epithelium. It is the eye's protective layer. The epithelium is made up of highly regenerative cells, which have the ability to grow back within three days.
Conjunctiva
The conjunctiva lines the outer sclera and provides a protective barrier for the eye. Tiny secretory glands in the conjunctiva produce the tear film to lubricate the surface of the eye.
Iris
The iris is the colored part of the eye. (i.e. blue, green, brown, and hazel.) The primary function of the iris is to control the size of the pupil. This is achieved through contractions or expansions of the muscles of the iris.
Pupil
The pupil is the 'black circle' seen in the eye. The function of the pupil is to control the amount of light entering the eye. If the environment is dark, the pupil expands to allow more light to enter and reach the back of the eye. In bright light, it becomes smaller to allow less light to enter the eye.
Lens
The lens, is a clear structure located behind the pupil. It fine-focuses the images we see. This is accomplished by altering its shape. Around age 45, many lens become less flexible. This is transition with age. The condition is called presbyopia. For many people the lens can become cloudy and hard due to cataracts.
Retina
The retina is the delicate membrane of light-sensitive nerve tissue. It lines the inside wall of the eye and it acts much like the film in a camera, capturing an image and converting it into electrical impulses, which are transmitted to the brain.
Sclera
The sclera represents the part that is known as the white of the eye. The sclera's purpose is to provide structure, strength and protection to the eye.
Vitreous Body
This is a clear, gel-like substance located inside the eye. It fills the interior of the eye.
Optic Nerve
The optic nerve carries image signals from the retina to the brain.
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