THE eyesight it is an extremely important sense, as it allows us to see everything around us, differentiate colors, see the wonders of nature and even read this text. Our eyes are the organ responsible for making it possible to receive these messages.
The eye is made up of several parts, including the cornea, aqueous humor, lens (former lens), vitreous humor, pupil, and retina. In addition, we have muscles and nerves that enable the movement of the eyes and the transmission of signals to the brain, respectively.
We call the cornea a transparent layer that covers the eye in its anterior portion. The lens, on the other hand, is the part of the eye responsible for making the luminous image sharper. On the anterior portion of the lens there is a colored membrane that is called the iris. It is responsible for controlling the size of the pupil, a small opening that allows light to enter the eyeball. Bathing the lens, iris and pupil is a liquid called aqueous humor. The rest of the eye is bathed in vitreous humor.
In the inner part of the eye there is the retina and it is in this that the cells that capture the luminous information are located. We call these sensory cells photoreceptors and they can be of two types: cones and rods. Cones are related to color perception, while rods are more related to light capture.
Schematic showing eye structure and retinal detail
In darker places only the rods come into action, that's why we can't distinguish the colors in dimly lit places. As the light increases, the cones start to be stimulated and we can perceive the colors of the objects. There is a spot on the retina where neither cones nor rods are found, this region is called the blind spot.
In order to perceive the luminous messages and transform them into images, light follows certain paths. First it enters the eye through the pupil. Then it goes through the aqueous humor until it reaches the lens. It then projects onto the retina, where it is transmitted to the optic nerve. The nerve impulse travels to the brain and is interpreted there.
Some diseases affect the human being's vision, among them, we can mention: hyperopia, myopia, astigmatism, glaucoma and cataracts. Hyperopia is characterized by the difficulty of seeing up close, while in myopia the difficulty is in seeing objects from a distance. Astigmatism makes it difficult to focus objects in some directions. Glaucoma is a condition in which there is increased pressure in the eye, which can lead to blindness. Cataracts are characterized by the opacity of the lens.
If you experience any difficulty seeing, constant headaches or blurred vision, consult your doctor!!!
By Me. Vanessa dos Santos
Take the opportunity to check out our video lesson on the subject:
