The ability to see clearly and distinctly is a unique feature not only of humans, but also of animals. With the help of vision, orientation in space and the environment occurs, and a large amount of information is obtained: it is known that with the help of the organ of vision, a person receives up to 90% of all information about objects and the environment. The unique structure and cellular composition allowed the retina not only to perceive sources of light stimulation, but also to distinguish their spectral characteristics. Let's take a look at how the retina is arranged, the functions and features of its neuronal organization. But we will only talk about its structure not from the point of view of a person carrying a load of scientific knowledge, but from the point of view of an average citizen.
Functions of the retina
Let's start with the main points. The answer to the question, what are the main functions of the retina of the eye, is quite simple. First of all, this is the perception of light irritation.
By nature, light is an electromagnetic wave with a certain frequency of oscillation, whichcauses the retina to perceive different colors. The ability for color vision is a unique feature of mammalian evolution. With the help of scientific achievements, modern equipment, new luminescent chemical compounds, it was possible to look deeper into the structure of the organs of vision, clarify biochemical processes and better understand how the retina implements its functions. And as it turns out, there are many of them, and each is unique.
Retina of the eye: structure and functions
Many people know that the retina is located inside the eye and is its innermost shell. It is known that in its composition it contains the so-called photosensitive cells. Directly thanks to them, the retina performs the functions of photoreception.
Their names come from the shape of the cells. So, rod-shaped cells were called "rods", and cells that looked like a chemical vessel called "flask" were called "cones".
Rods and cones differ from each other not only in the features of the histological structure. The main difference between them is how they perceive light and its spectral characteristics. The rods are responsible for the perception of the light flux at twilight - exactly when, as they say, "all cats are gray." But the cones are responsible for the perception of color vision.
Functional features of cones
Among the cones, there are three special classes: the cones responsible for the perception of the green, red and blue parts of the spectrum, respectively. EachThe cone contributes to the formation of color vision by processing the image projected by the lens. In painting, the formation of the final color depends on the proportions in which the colors were originally taken by the artist. Similarly, the retina transmits information about the spectral characteristics of light: depending on how the cones of each group are discharged with impulses, we see a particular color.
For example, if we see green, then the cones responsible for the green region of the spectrum are discharged most strongly. And if we see red, then, accordingly, for red. Thus, the functions of the human retina are not only in the perception of the light flux, but also in the primary assessment of its spectral characteristics.
Retinal layers and why they are needed
Perhaps someone thinks that immediately after the lens, the light directly hits the rods and cones, and those in turn are connected to the fibers of the optic nerve and carry information to the brain. Actually it is not. Before reaching the rods and cones, the light must overcome all the layers of the retina (and there are 10 of them) and only after that act on the light-sensitive cells (rods and cones).
The outermost layer of the retina is the pigment layer. Its task is to prevent the reflection of light. This layer of pigment cells is like a black chamber.film camera (it is black that does not create glare, which means that the image becomes clearer, light reflections disappear). This layer provides the formation of a sharp image using the optical media of the eye. In the immediate vicinity of the layer of pigment cells, rods and cones are adjacent, and this feature makes it possible to see sharply. It turns out that the layers of the retina are located, as it were, backwards. The innermost layer is a layer of specific cells, which, through the mediator cells of the middle layer, process incoming information from rods and cones. The axons of these cells gather together from the entire surface of the retina and leave the eyeball through the so-called blind spot.
There are no light-sensitive rods and cones in this place, and the optic nerve comes out of the eyeball. Moreover, it is here that the vessels that provide retinal trophism enter. The state of the body can be reflected in the state of the vessels of the retina, which is a convenient and specific criterion for diagnosing various diseases.
Localization of rods and cones
Nature designed so that the rods and cones are unevenly distributed over the entire surface of the retina. The fovea (the area of best vision) has the highest concentration of cones. This is due to the fact that this area is responsible for the clearest vision. As you move away from the fovea, the number of cones decreases, and the number of rods increases. So the peripheryretina is represented only by rods. This feature of the structure provides us with a clear vision in high light levels and helps to distinguish the outlines of objects in low light.
Neuronal organization of the retina
Immediately behind the layer of rods and cones are two layers of nerve cells. These are layers of bipolar and ganglion cells. In addition, there is a third (middle) layer of horizontal cells. The main purpose of this group is the primary processing of afferent impulses that come from rods and cones.
Interesting facts about the structure of the retina
Now we know what the retina is. We have already considered its structure and functions. It is also necessary to mention the most interesting facts related to this topic.
In order to reach the pigment layer, light must pass through all the layers of nerve cells, penetrate the rods and cones, and reach the pigment layer!
Another feature of the structure of the retina is the organization of providing clear vision in the daytime. The bottom line is that in the fovea each cone connects to its own ganglion cell, and as it moves away to the periphery, one ganglion cell collects information from several rods and cones.
Retinal diseases and their diagnosis
So what is the function of the retina? Of course, this is the perception of the light flux, which is formed by the refractive media of the eye. Violation of this function leads to violations of clear vision. ATophthalmology, there are a large number of diseases of the retina. These are diseases caused by degenerative processes, and diseases based on dystrophic and tumor processes, exfoliation, hemorrhages.
The main and primary symptomatology that may indicate diseases of the retina is a visual acuity disorder. In the future, optical circles, loss of visual fields and many other symptoms may occur. It must be remembered that with a decrease in visual acuity, you should immediately consult an ophthalmologist and undergo the necessary examination.
Conclusion
Vision is a huge gift of nature, and the retina, functions and its structure are a finely organized element of the eyeball both structurally and functionally.
Timely consultation and preventive examinations by an ophthalmologist will help to identify diseases of the visual analyzer and start treatment on time. Fortunately, modern medicine has unique technologies that allow you to get rid of visual disorders in just 20-30 minutes and regain the ability to see clearly. And knowing what function the retina performs, you can restore it.
