We explain what vision is, the anatomy and functioning of this sense, as well as its general characteristics, defects and more.
What is Human Vision?
Vision is one of the most important senses, responsible for interpreting our environment from the light that reaches our eyesIt is based on the transduction of a physical signal, the light captured by our eyes in the form of an electromagnetic wave, into an electrical signal in the neurons that results in a projection in the form of an image of our surroundings.
Through the sight We receive approximately 50% of the information about our environmentmaking it one of the most important senses. It is based on a complex system that requires extremely precise adjustment of various parts of the body, and defects in it are among the most common conditions in humans.
See also: Touch.
Vision characteristics:
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Studies
Although In Greek times there were already attempts to explain the meaning of visionIt was not until the 19th century that the first scientific studies began, led by Hermann von Helmholtz, who argued that much of what we saw was the result of unconscious inferences. In the 20th century, the Gestalt movement and the idea of indirect perception appeared, much closer to the concept we have today.
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Anatomy
The eye can be divided into the anterior and posterior parts.The first is made up of the conjunctiva, a mucous membrane that helps lubricate the eye; the cornea, a layer of epithelial cells; the iris, the pupil and the lens. The posterior part is made up of the vitreous humor, a transparent gel that occupies most of the eye and the retina, which is the light-sensitive part.
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Resolution
Resolving power is the minimum distance at which the eye is able to distinguish that two points are separatedIt depends on several factors such as the size of the retinal cells, the light in the environment, the diameter of the pupil and the separation between the retinal receptors.
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Light
The light is the most important element that allows vision as we know itWhat our eyes capture is the light reflected by other objects and thanks to this and the transduction of this signal, our brain is able to make an interpretation of the space around us.
More in: Light.
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Physiology
Light rays reach the eye and must pass through the cornea, which is transparent and protects the iris and lens. The iris controls the size of the pupil to regulate the amount of light that reaches the eye. The crystalline lens is a lens that helps focus images correctly.increasing or decreasing its thickness by means of the ciliary muscles in a process known as accommodation. The projection of the lens goes directly to the retina.
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Neural pathway
The retina is the back surface of the eye and is covered by visual receptors known as rods and cones. These pass information to bipolar cells in the centre of the retina, which in turn transmit the signal to ganglion cells. The axons of these ganglion cells join together to form the optic nerve. that reaches the brain.
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Colors
The perception of colors is very different depending on the animal since depends on specialized cells known as conesIn humans there are three types of cones, each sensitive to a different spectrum of light, which correspond roughly to the colors red, green and blue.
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Binocular
Most vertebrates, including humans, have binocular vision. Each of our eyes forms a different image on its retina and it is the superposition that the brain makes of these two images that is the perception of vision that we finally have and that allows us to see objects in three dimensions.
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Boundaries
Although vision in humans is highly developed, it is a sense that has limitations when compared to other animals. The human eye can distinguish approximately one million colors. and requires at least one photon of light to capture an image. It is not possible to establish the smallest or most distant object that our eye can capture since they depend on the photons that reach our eyes.
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Defects
Vision defects are very common in humans. The most common are myopia, which is a consequence of excessive convergence of light in the eye, hyperopia due to lack of convergence, Presbyopia due to the rigidity of the lens that is unable to adaptastigmatism due to deformations in the cornea and cataracts caused by opacity of the lens.