KOMPAS.com – The eye is a very unique organ in the body. With our eyes, we can see the world and even convey emotions.
Considering its extraordinary function, what are human eyes actually made of?
The main structures of the eye
Before going any further, what you need to know first is the main structure of the eye. Dr. Parwez Hossain, professor of ophthalmology at the University of Southampton, England, said that the structure of the eye is similar to a camera.
The eye has a frontal optical system consisting of the cornea and lens, as well as a photosensitive area, called the retina.
The cornea is the smooth surface at the front of the eye that covers the lens and focuses most of the light that hits the eye onto the retina at the back of the eye.
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The cornea is mostly made up of a protein called collagen, which is arranged in a very regular pattern, which helps light pass through the eye.
Collagen also strengthens the eyes. This function is important because the cornea is very open and therefore susceptible to damage.
Behind the cornea, there is a lens that focuses the remaining light that enters the retina. The lens is made of proteins that keep it transparent and make it flexible so it can change shape and allow us to see objects, both near and far.
Then, Hossain called the retina part like photographic film. The retina consists of 10 layers of nerve cells or neurons, including rod and cone photoreceptor cells that react to light.
When illuminated, these cells produce electrical impulses. These impulses then travel down the optic nerve, which is behind the eye, and into the brain, where the impulses are interpreted as vision.
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Hossain explained that many other structures in the eye also support vision. This includes the conjunctiva, which is the thin, clear, protective outer membrane that lines the inside of the eyelids and covers the white part of the eye called the sclera.
There is also a colored part of the eye called the iris, which consists of muscles that control the size of the pupil, a black dot inside the iris that allows light to enter the lens.
The color of the iris depends on how much pigment called melanin it contains. Then, there are fluids, such as the vitreous humor and aqueous humor, respectively, maintaining the shape of the eye and nourishing it.
The structure of the eye changes with age
As we age, the composition and structure of the eye changes. One of the main areas of the eye that changes is the lens.
As lenses age, they stiffen and lose their ability to change shape during focusing. In middle age, this loss of focusing ability means we need reading glasses for near focus.
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The lens also becomes less transparent and can create “cloudy” areas called cataracts.
Another common age-related eye disease is age-related macular degeneration (AMD), which occurs in the central area of the retina called the macula.
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2023-10-07 12:00:00
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