The vast majority of people forget about the laws of physics as soon as the need to learn them disappears. But after all, this science is the whole life of each person individually and of all mankind together. For example, either physicists or ophthalmologists can clearly answer the question of what refraction is. After all, it is this physical phenomenon that serves as the basis of vision.
Science is everywhere
Physics is the whole world of man. Physical processes inside the body ensure the coordinated work of organs and systems. The term "refraction" in translation from English means "refraction". Types of refraction depend on the field of work. Hydroacoustics studies the refraction of sound waves in water, astronomy deals with the refraction of celestial bodies. If we talk about the human body, then ophthalmology uses the term "refraction" here. The very phenomenon of wave refraction is based on the basic laws of physics: the law of conservation of energy and the law of conservation of momentum.
Refraction as the basis of vision
The human visual apparatus is a complex systemperception of the world, capable of perceiving and converting the energy of electromagnetic radiation of the visible light spectrum into a color image that creates a picture of the surrounding world. Numerous processes, both physical and biochemical, provide the quality and features of human vision. One of these components is refraction. This is the process of light refraction as it passes through the components of the visual system: the anterior and posterior surfaces of the cornea and lens. It is this process that determines the main quality of human vision, colloquially called visual acuity and determined by specialists in diopters.
Types of refraction
Since the basis of vision is the refraction of the rays of the spectrum when passing through the structures of the visual system, the quality of this process determines the types of refraction of the eye. Assuming a clear projection of what is visible on the retina, we are talking about good vision, which depends on a pair of anatomical components of the visual system - on the refractive power and on the length of the optical axis of the eye. For each person, these parameters are individual, and therefore we can talk about a physical phenomenon, the characteristic of which is precisely the refractive power of the optical system of vision, which depends on the anatomy of the eye of a particular person, and about the ophthalmological manifestation of this physical property. The main parameter characterizing the quality of vision is clinical refraction. This term refers to the ratio of the main focus of the optical system and the retina.
Considering the question of human vision, one should understand which refraction becomes the mainan indicator of the quality of vision and makes a person resort to the help of special devices - glasses, contact lenses, or surgical intervention to correct the work of the optical system of the eye. This area of human he alth concerns specifically clinical refraction.
Far and close
Poor vision is a big problem, although the same glasses have become an accessory of style and taste, and lenses help improve vision and change eye color. But this is only an external paraphernalia, which most people resort to because of the need to correct the optical system of the eye. The degree of refraction, namely this physical phenomenon - the basis of vision, is determined by a specialist in diopters. Diopter - the optical power of axisymmetric optical systems, for example, lenses, determined by a focal length of 1 meter. The normal ratio of the length of the axis of the eye and the focal length give a clear image obtained on the retina and processed by the brain. This refraction is called emmetropic. With such vision, an individual can see both very distant objects, the dimensions of which are accessible to human vision, as well as nearby and small details. But, unfortunately, most people in the modern world suffer from visual impairments. In most cases, it manifests itself due to malfunctions in the optical system of vision, refraction, in particular.
If the refraction of light rays during the passage of the optical system of the eye is broken, then experts talk about ametropia, which is divided into three varieties:
- astigmatism;
- hyperopia;
- myopia.
The difference in refraction or its violation can be either congenital or acquired. The type of visual impairment and its degree is determined only by a specialist using special ophthalmic equipment. Myopia in everyday speech is called myopia, and hypermetropia - farsightedness. A more complex combination of disturbances in the perception of light rays by all components of the optical system of the eye is called astigmatism.
Child's vision
One of the tasks of a neonatologist examining a newborn baby is to establish the features of his vision. This is due to the fact that in some cases the child may have congenital disorders that require prompt medical intervention. A child is born with an underdeveloped visual system, which must adapt to the world around him. In the first weeks of life, the baby sees the world only as bright spots, which gradually acquire more and more clear contours and shades. Due to the special structure of the visual organs, hypermetropia is developed in newborns - farsightedness, disappearing over time - by the age of three years of a child's life. Normally, refraction in children becomes definite only by the age of 6-7 years. But already in the first six months of life, an ophthalmologist can identify some accommodation disorders and prescribe special glasses that help the child's visual apparatus develop correctly.
Myopia
The refraction of the eye in children and adults may be impaired due to elongationthe central axis of the eye, while the resulting image is focused not on the retina, but in front of it. The image of distant objects is blurry, muddy. To normalize such a visual impairment, the specialist recommends corrective glasses with diverging lenses - with negative diopters. If it is established that myopia requires the use of lenses from -0, 1 to -3 diopters, then the degree of impairment is considered weak. Correction of vision with glasses from -3 to -6 diopters is used for the middle stage of myopia. More than -6 diopters is a sign of severe myopia. It is noteworthy that a weak degree of myopia is "corrected" by many people, so to speak, with the help of squinting and staring at the observed object. This stimulates accommodation, that is, it increases the tension of the ligamentous-muscular apparatus of the eye, due to which the length of the central axis of vision is reduced. But the higher the degree of myopia, the less this method helps.
Hyperopia
When the image is focused behind the retina, refractive error is called hypermetropia, otherwise farsightedness. The reason for this may be as follows:
- too short central axis of the eye;
- changing the shape of the lens;
- disturbance of accommodation.
With age, many people experience a natural correction of vision, in which the existing myopia disappears, giving way to the so-called senile farsightedness - presbyopia. Although it will be natural for most older people to usetwo pairs of glasses - one for looking into the distance, the other for reading books. The natural processes of aging of the body also affect the tone of all components of the visual system, including accommodation. Due to this, the central axis of the eye is shortened, the perceived image becomes clearer only when it is at a certain distance. The vision of a person over the age of 45-50 often becomes "outstretched vision", when in order to read the text of a book, labels, you have to move it some distance from the eyes.
Contrary to the opinion of many ordinary people, farsightedness is not any advantage over myopia. It's all about the simpler accommodation of vision when observing distant objects compared to near objects considered.
Hypermetropia is measured in diopters with a plus sign. These lenses allow you to focus the image of nearby objects, making it clearer.
Astigmatism
In some cases, a patient's visit to an ophthalmologist becomes a reason for a thorough examination, because sometimes the determination of refraction in a regular clinic is difficult because the patient has a certain type of astigmatism - a violation of the refraction of light waves in each component of the optical system of vision. In this case, it is quite difficult to choose glasses without using certain equipment, because in the same eye, but in its different meridians, both myopia and hyperopia are possible, and the combinations can be very different. This visual impairment isin that it is difficult for the patient to clearly see objects both at a distant and near distance. Correction of such a vision problem is possible only by the selection of a special combination of lenses in the frame, that is, glasses. Contact lenses are not used for astigmatism.
Vision diagnostics
When examining refraction in the ophthalmologist's office, the type and degree of visual impairment is determined. The patient is prescribed corrective glasses or contact lenses with a certain number of diopters with a plus or minus sign. How does the diagnostic process work? This procedure has been known to everyone since childhood - a visitor to the ophthalmologist's office is invited to sit at a certain distance from a special table and, closing one eye, read the indicated letters or symbols with the other eye. To make this method of diagnosing visual acuity more accurate, it is necessary to minimize the natural accommodation of vision. It is for this purpose that certain medicinal substances are instilled into the patient's eyes, temporarily paralyzing the ciliary muscle of the eye, that is, causing cycloplegia. Atropine is usually used, the effect of which disappears only a few hours after administration, which causes some discomfort of this diagnostic technique. During the period of reduction of accommodation under the influence of the drug, the oculist or ophthalmologist offers the patient special lenses or a set of lenses, with the help of which the degree of visual impairment is determined, and corrective glasses are selected. The refraction of the cornea and lens will be quite noticeablechanged if accommodation is involved in the process of vision. In some cases, the process of refraction of light rays in the eye system must be studied in dynamics, for example, in case of farsightedness. In this case, cycloplegia is not used.
Treatment of visual impairments
When answering the question of what refraction is, one should always remember that physics is the essence of the processes of life itself. The refraction of light rays in the optical system of vision is the main indicator of visual acuity. This means that refraction is the most important component of high-quality visual perception of the surrounding world.
If a person does not see well into the distance, then such a problem is called myopia or myopia. Hypermetropia - the ability to see distant objects and poorly distinguish near ones. Also, a person may suffer from astigmatism. The vast majority of those who see poorly prefer to use special devices - glasses or contact lenses.
It is a big mistake, according to experts, to talk about the treatment of visual impairment, in particular about such a side as clinical refraction, with folk methods at home. Such techniques can serve as qualitative ways to prevent the development of disorders or slow the progression of existing problems.
Surgery
Determination of the refraction of the human visual apparatus is carried out only in specialized medical institutions. An optometrist will determine the degree of impairment and recommend a method for correcting vision. The surgical method is gaining popularityrefraction recovery. Modern ophthalmology has the technique of surgical correction of vision, allowing you to eliminate existing defects in the optical system of the eye. Such an intervention is carried out by several methods, each of which is constantly being improved. The most effective and least traumatic laser vision correction surgery.
This intervention helps to correct the optical surfaces of the vision system. The method of correction of the superficial layers of the cornea is called photorefractive keratectomy. Ablation, that is, the removal of layers of the cornea, helps to change its thickness, curvature, due to which the length of the refraction beam changes and the resulting image is focused directly on the retina. This type of intervention is the most gentle, has a short period of postoperative recovery - a maximum of 4-5 days. However, this period is characterized by significant discomfort until epithelialization. Visual functions after this operation are restored within a month. As a complication after PRK, clouding of the cornea, scarring of the epithelial layer can develop, which is prevented by the correct prescription of special medications.
Exercise for vision
From childhood, a person must protect his eyesight. This is facilitated by special exercises aimed at stimulating proper accommodation. Clinical refraction - an indicator of the quality of optical perception, depends on the work of the ligamentous-muscular apparatus. To maintain accommodation in the rightcondition should perform certain exercises.
For example, to look from a near point to a far one, which are located on the same straight line in front of the eyes. Or look right and left without turning your head. Also look up and down. These exercises can be performed in any environment. Contacting a specialist will help you choose the necessary set of exercises that can maintain or even improve the functioning of the visual system.
Vitamins in a plate
The answer to the question, what is refraction, can be very simple. After all, light waves perceived by the eye are refracted as they pass through the components of the visual system, due to which the brain receives signals to be processed. And if the refraction occurs with violations, then the image is incorrect. In this case, a person has poor vision that requires correction. Like the rest of the body, vision needs a complete set of significant vitamins, micro- and macroelements, and other biologically active substances. They can be found in special vitamin and mineral complexes recommended by a specialist. But food can also make up for the deficiency of these components. Thiamine, riboflavin, retinol, ascorbic acid, tocopherol, zinc, lute, zeaxanthin, polyunsaturated fatty acids are important for vision. They are present in many vegetables and fruits, liver, fish, dairy products. A complete, balanced diet will help preserve your eyesight.
Answering the question of what refraction is in ophthalmology, one should not talk so much aboutthe physical phenomenon itself, how much about the fact that it is the basis of the quality of vision. It is the violation of the refraction of light rays when passing through the optical system of the eyes that causes myopia, hypermetropia or astigmatism. Currently, half of the world's population suffers from these vision problems. To improve vision, a person has to use refractive correction techniques of the visual apparatus - glasses, contact lenses or surgery.
