The laws of physics, the vast majority of people forget immediately, as soon as the need to teach them disappears. But this science is the whole life of each person individually and of all mankind together. For example, 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 within the body ensure the smooth functioning of organs and systems. The term "refraction" in translation from English means "refraction". Types of refraction depend on the area of ​​work. The refraction of sound waves in water is studied by hydroacoustics, astronomy is engaged in the refraction of celestial bodies. If we talk about the human body, then ophthalmology uses the term "refraction" here. The phenomenon of wave refraction itself 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 the most complex system of world perception, 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 world. Numerous processes, both physical and biochemical, ensure the quality and characteristics of human vision. One such component is refraction. This is the process of refraction of light when passing through the components of the visual system: the front and rear surfaces of the cornea and lens. It is this process that determines the basic quality of human vision, called colloquial 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 the eye visible on the retina, we are talking about good vision, depending on the pair of anatomical components of the visual system - on the refractive power and on the length of the optical axis of the eye. Each person has these individual parameters, and therefore we can talk about a physical phenomenon, the characteristic of which is the refractive power of the optical system of vision, which depends on the anatomy of the eye of a particular person, and 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.
When considering the issue of human vision, one should understand what refraction becomes the main indicator of the quality of vision and makes a person resort to special devices - glasses, contact lenses or surgical intervention to adjust the operation of the optical system of the eye. This area of ​​human health relates specifically to 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 both improve vision and change eye color. But this is only an external paraphernalia, which most people resort to because of the need to adjust 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 is 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 of the eye and processed by the brain. This refraction is called emmetropic. With this vision, the individual can see as very far located objects, the sizes of which are accessible to human vision, as well as the nearest and small details. But, unfortunately, most people in the modern world suffer from visual impairment. In most cases, it manifests itself due to malfunctions of the optical system of vision, refraction, in particular.
If the refraction of light rays when passing through the optical system of the eye is violated, then experts say about ametropia, which is divided into three varieties:
- astigmatism;
- hypermetropia;
- 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 with the help of special ophthalmological equipment. Myopia in everyday speech is called myopia, and hyperopia is called 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 who examines a newborn baby is to establish the features of his vision. This is due to the fact that in some cases a child may have congenital disorders that require prompt medical attention. A child is born with an underdeveloped visual system that must adapt to the world. In the first weeks of life, the baby sees the world only with bright spots, which gradually acquire increasingly clear contours and shades. Due to the special structure of the visual organs in newborns, hyperopia is developed - hyperopia, which disappears over time - by three years of a child’s life. Normally, refraction in children becomes certain only by 6-7 years. But already in the first six months of life, an ophthalmologist can detect some disturbances in accommodation and prescribe special glasses to help the child’s visual apparatus develop correctly.
Myopia
Eye refraction in children and adults may be impaired due to lengthening of the central axis of the eye, while the resulting image focuses 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 scattering 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 violation is considered weak. Vision correction with glasses from -3 to -6 diopters is used in the middle stage of myopia. More than -6 diopters are a sign of severe myopia. It is noteworthy that the low degree of myopia by many people is “corrected,” so to speak, by squinting and staring at the observed object. This stimulates accommodation, that is, 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.
Farsightedness
When focusing the image behind the retina, the violation of refraction is called hyperopia, otherwise hyperopia. The reason for this may be as follows:
- too short central axis of the eye;
- change in the shape of the lens;
- violation of accommodation.
With age, many people have a natural vision correction, in which the existing myopia passes, giving way to the so-called senile hyperopia - presbyopia. Although for most older people it would be natural to use two pairs of glasses - one to look into the distance, the other to read books. The natural processes of aging 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 picture becomes clearer only when it is at a certain distance. Vision of a person after the age of 45-50 years often becomes "the vision of an outstretched arm", when in order to read the text of a book, a label, one has to move it a certain distance from the eyes.
Contrary to the opinion of many ordinary people, farsightedness is not an advantage over myopia. The thing is in a simpler accommodation of sight when observing distant objects in comparison with the considered near objects.
Hypermetropia is measured in diopters with a plus sign. Such lenses allow you to focus the image of nearby objects, making it clearer.
Astigmatism
In some cases, the patient’s visit to the ophthalmologist becomes the 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 vision system. In this case, picking up glasses is quite difficult without the use of certain equipment, because in the same eye, but in its different meridians, there may be both myopia and hyperopia, and combinations can be very different. Such visual impairment is expressed in the fact that it is difficult for the patient to clearly see objects both at long and near distances. Correction of such a problem with vision is possible only by selecting a special combination of lenses in the frame, that is, glasses. Contact lenses are not used for astigmatism.
Vision diagnostics
In the study of refraction in the office of an ophthalmologist, 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 is the diagnostic process going? This procedure has been known to everyone since childhood - a visitor of the ophthalmologist’s office is invited to sit at a certain distance from a special table and, with one eye closed, read the indicated letters or symbols with his second 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 reason 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 passes only a few hours after administration, which causes some discomfort of this diagnostic technique. During the period of accommodation reduction under the influence of the medicine, the ophthalmologist or ophthalmologist offers the patient special lenses or a set of lenses with which the degree of visual impairment is determined, and corrective glasses are selected. Refraction of the cornea and lens will be noticeably altered 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, with farsightedness. In this case, cycloplegia is not used.
Treatment for visual impairment
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 this problem is called myopia or myopia. Hypermetropia is 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.
According to experts, it is a big mistake to talk about the treatment of visual impairment, in particular about its side, such as clinical refraction, by 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 refraction of the human visual apparatus is carried out only in specialized medical institutions. An ophthalmologist will determine the degree of impairment and recommend a method for correcting vision. The surgical method of refraction recovery is gaining popularity. Modern ophthalmology has the technique of surgical vision correction, 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 less traumatic surgery to correct vision with a laser.
Such an intervention helps to correct the optical surfaces of the vision system. The correction technique for the surface layers of the cornea is called photorefractive keratectomy. Ablation, that is, removal of the layers of the cornea, helps to change its thickness, curvature, due to which there is a change in the length of the refraction beam and focusing the resulting image 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 epithelization. Visual functions after this operation are restored within a month. As a complication after PRK, clouding of the cornea, scarring of the epithelial layer may develop, which is prevented by the correct appointment of special medications.
Charging for vision
From childhood, a person must take care of his vision. 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 required state, certain exercises should be performed.
For example, to look from a near point to a distant one, which are located on one 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. Turning to a specialist will help you choose the necessary set of exercises that can preserve or even improve the functioning of the visual system.
Vitamins in a plate
The answer to the question of what is refraction can be very simple. Indeed, the light waves perceived by the eye are refracted when passing 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, the person has poor eyesight that needs correction. Like the whole body, vision requires a complete set of significant vitamins, micro and macro elements, and other biologically active substances. They can be found in special vitamin-mineral complexes, which are recommended by a specialist. But food can make up for the shortage 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 vision.
Answering the question of what refraction is in ophthalmology, one should speak not so much about the physical phenomenon itself, but about the fact that it is the basis of the quality of vision. It is a violation of the refraction of light rays when passing through the optical system of the eye that causes myopia, hyperopia, or astigmatism. Currently, these vision problems affect half the world's population. To improve vision, a person has to use methods of correcting refraction of the visual apparatus - glasses, contact lenses or surgery.