The eyes are made up of a series of structures, several of them are totally crystalline and this is what allows the entry of light, which is essential for vision. The eyes are responsible for detecting light until it is converted into nerve impulses, in order to generate vision . It is undoubtedly one of the most important organs of the five senses.

People with good eyesight perceive up to 80% of the visual information in the world, that is, thanks to the work done by the eyes in coordination with the brain, we can distinguish images and moving objects, recognize patterns and shapes and see in three dimensions, in addition to being able to distinguish between everything a color band. Our vision can be adapted to different degrees of illumination, since by expanding the pupil the eye allows us to obtain 30 times more light.

What is the function of the eyes?

The human eye performs multiple functions, of which we can highlight the following:

  • The main function of the eyes is to distinguish the brightness, color, shape, size of observed objects and their movements.
  • It fulfills the same function as a photographic camera, frames and focuses the images properly, due to the lenses it has inside.
  • The eyes give us stereoscopic vision . As the eyes are next to each other, at a distance of only 6 cm, we can observe the objects with each eye at different angles.
  • The eyes offer us a binocular vision that helps us perceive the depth of space.
  • Each eye constantly adjusts the amount of light it lets in, focuses on near and far objects, and produces continuous images that are instantly transmitted to the brain.
  • The eyes are spherical so they can easily rotate around three axes: vertical (from left to right), horizontal (up-down) and axis that coincides with the optical axis of the eye.

What are the external parts of the eyes?

The human eye is a fairly complex organ, and among its external parts we can mention:

  • The eye or eyeball: which is located in the orbital cavity in the facial part of the skull.
  • Auxiliary eye formations: these include the eyelids, eyelashes, the lacrimal gland along with the tear system, which protect and nourish the outer part of the eye. There are also the oculomotor muscles that are attached to the outer surface of the eyeball to ensure its movement and the eye movements of the eyelids.

What are the internal parts of the eye and their functions?

The eyes on the outside have the following parts:

1. The cornea

It is the transparent portion to the front of the eye. Its curved shape facilitates the convergence of light rays. Injuries or conditions can cause scarring or clouding of the cornea, which can lead to loss of vision.

2. The pupil

It is a darkened, rounded fragment that is like the inner window of the eye. It works as a diaphragmatic structure that regulates the intensity of the incoming light: with a large amount of light it becomes small and with little light it expands. The pupil is the natural orifice of the iris, which is the inner part that gives color to the eyes.

3. The lens

It is a lens that is located behind the pupil and through which the image is transferred to the eye, it acts like the lens of a photographic camera. It has a power of approximately 22 diopters, but its flexible stability grants it automatically, transforming its power by admitting seeing from afar, and focusing on nearby objects as when we do a reading.

4. The retina and optic nerve

After passing through the vitreous humor, which is a transparent gelatinous structure, the images finally reach the back of the eye, where they are captured by the retina. The retina behaves like a photographic film where it is placed behind the camera in such a way that it processes all the images to then be sent to the brain through the optic nerve.

5. Nutrition of the eye

The ocular system is nourished by sustenance that arrive through veins and arteries, which are located in a layer between the sclera and the retina that we know as the uvea or choroid.

What is the structure of the eyes?

The eye is made up of internal layers that surround it in its entirety, and these are:

Sclera : It is the outer layer of the eye, fibrous and white. Its front part is perceptible between the eyelids, it has a central translucent spherical surface that we know as the cornea.

Choroid : It is located inside the sclera, this layer contains the blood vessels of the eye.

Retina : It is the deepest layer of the eye, made up of nerve endings that go towards the back of the eyeball that give rise to the optic nerve, which is responsible for transmitting the electrical impulses captured by the eye towards the brain. The retina also contains the macula, which is responsible for accommodating central vision, which is considerably sharper than peripheral vision.

Iris : It is a disc-shaped structure that provides color to the eye. It is like a diaphragm that has an opening called a pupil. The iris can enlarge and reduce its size, since it is in charge of regulating the light that enters the eye.

Vitreous body : It is a translucent and soft liquid that fills the inner part of the eye at the back, providing it with strength. It is located behind the lens.

Crystalline : It is a crystalline lens that is located behind the iris, which has the ability to change its shape in order to carry out the adaptation of the eye, which is necessary to focus clearly on objects at any distance.

Aqueous humor : It is a translucent and viscous liquid that is located between the lens and the cornea. One of its missions is to provide nutrients and oxygen to both the cornea and the lens. These structures lack blood vessels.

What are eye diseases?

For the human being the eye is of utmost importance, since this organ allows us to appreciate what surrounds us, through vision and among other things it helps us to perceive the environment, differentiate colors and also through sight we receive around 80% information.

The eye is an extremely delicate organ, and like all the organs of the body, sometimes they present diseases, such as:

  • Conjunctivitis: It is the inflammation of a membrane that surrounds the inside of the eyelids called the conjunctiva. The most common symptoms of this disease are redness, photophobia and tearing. It is contagious, although there is also an allergic type.
  • Hyperopia: It is characterized by the difficulty of focusing vision on objects near the eye. It is one of the most frequent ailments, it does not produce serious consequences nor is it progressive. This condition is treated with corrective glasses or laser surgery.
  • Myopia: This makes it difficult to see correctly objects that are at a far distance. This condition can be corrected with the use of corrective glasses, contact lenses, with the implantation of intraocular lenses or with laser surgery.
  • Astigmatism: It consists of the difficulty of seeing objects in focus. In most cases one of the symptoms of this ailment is blurred vision, not being able to focus on objects in a normal way and in the worst or most serious of cases a noticeable decrease in vision. It has been scientifically proven that the symptoms of astigmatism are directly associated with hyperopia and myopia.
  • Strabismus: It consists of the loss of the eyes, if this condition is detected early, the correction can be successful. This disease is improved with special lenses, muscle exercises, or patches. Surgery is also used, in the most serious cases.
  • Presbyopia: It is the progressive loss of sight that prevents objects that are close to the eye from seeing clearly. This condition begins to manifest itself around 40 to 50 years. Presbyopia can be corrected with the use of corrective lenses or glasses.
  • Cataracts: It is a condition that usually appears after the age of 50. It consists of the progressive loss of clarity of the lens, which causes difficulty for light to penetrate the eye. If it is not treated in time, it can cause total blindness.
  • Glaucoma: Inside the eye there is a watery fluid that supports and provides oxygen to some intraocular structures such as the cornea or the lens. If the pressure of this fluid is high, this eye condition known as glaucoma arises. The treatment does not imply the cure of the disease but rather the arrest of its worsening, and it is treated through surgeries and lasers.
  • Retinal detachment: There is no cause or established age to predict the appearance of this condition. The main symptoms of this disease are the appearance of black dots in the vision, the distortion of objects and images observed, and in the worst case it generates the loss of visual acuity. It is treated with a laser or surgically. When the detachment is more arduous, an implant or a vitrectomy is placed in order to extract the vitreous as well and to be able to work on the retina.

Conclusion about the eyes

The human eye is of vital importance since it allows us to develop multiple activities. Through sight we can see what we do, we enjoy admiring colors, it allows us to observe people and our space, we can appreciate and enjoy nature and in turn we can contemplate the creations of man. In general, it is a blessing to be able to enjoy this and all the senses.

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Dr. Samantha Robson ( CRN: 0510146-5) is a nutritionist and website content reviewer related to her area of ​​expertise. With a postgraduate degree in Nutrition from The University of Arizona, she is a specialist in Sports Nutrition from Oxford University and is also a member of the International Society of Sports Nutrition.

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