Vision defect - what is it? You will learn the answer to the question posed from the presented article. In addition, you will receive information about the most common eye problems people experience and how to get rid of them.
General information
In medical practice, a visual defect is often called an anomaly of refraction. Such anomalies are the most common eye problems. The essence of this group of diseases is that the optical system of the eye is unable to focus light rays on the retina, which is our registrar of light stimuli. The main symptom and consequence of this pathological condition is poor vision.
Vision defect and its structure
This deviation can be of different nature. Today, several common visual defects stand out, namely:
- astigmatism;
- myopia, or the so-called myopia;
- farsightedness, or hypermetropia;
- color blindness, or color blindness;
- color agnosia.
To understand why this or that visual defect occurs, one should considerfeatures of the presented deviations in more detail.
Astigmatism
The reason for the development of such a pathological condition is an incorrectly formed cornea of the visual organ. It should also be noted that the development of astigmatism is directly affected by the displacement of the lens of the eye with respect to the axis of refraction. Both of these reasons entail differences in distances, which are essential for focusing the "picture".
Such a visual defect in one eye can combine the effects of farsightedness, nearsightedness and normal vision.
Myopia, or the so-called myopia
Myopia can develop for several reasons. The first is lengthening the eye while maintaining the correct refraction. As for the second reason, this is an overly powerful optical refraction, which is more than 60 diopters, with the length of the visual organ within the normal range. Both presented deviations adversely affect the acquisition of a normal image. In other words, the picture is not able to focus on the retina, but is located inside the eyeball. Thus, only a focused image of any objects that are at a short distance from a person penetrates the retina.
To correct this visual defect, patients are often prescribed special glasses to help build a clearer picture. In this case, a person can view objects in the distance without much tension. To the nearsightedthe patient saw more clearly, minus lenses are used to bring distant objects closer.
Far-sightedness, or hypermetropia
Such a defect develops due to excessively weak optical refraction in the visual organs while maintaining the normal length of the eyeball. It should be especially noted that the shortening of the eyeball also becomes the cause of farsightedness, provided that the refractive optical power is preserved.
Due to the fact that the farsighted eye is not able to focus on the retina, muscle tension increases significantly. This phenomenon gradually changes the curvature of the lens, which in turn leads to the adaptation of the visual organ to the prevailing conditions. However, this is not enough for normal focusing of the resulting image.
When examining objects near the eyes, the muscle tissues of this organ tense even more. In other words, the closer an object is, the further away its image appears on the retina.
What are the ways to eliminate visual defects, or rather, farsightedness? To correct this deviation, glasses with plus lenses are used. They help quite well in building the image.
As you know, when a baby is born, his eyes are slightly squeezed horizontally. That is why all small children are somewhat farsighted. However, as they develop, their vision gradually returns to normal.
If the degree of farsightedness in a person is small,far and near vision may be normal. But at the same time, people will complain of severe headaches and eye fatigue. If the degree of farsightedness is average, then this is manifested by poor near vision.
Color blindness, or color blindness
Such a defect is a congenital disease that is most often observed in men. The essence of this deviation lies in the fact that in patients the correct perception of color is disturbed, regulated by photoreceptor cells (cones) in the retina. If a person lacks any type of cones, then he has color blindness.
Color agnosia
Color agnosia is a variation of visual agnosia. With this disease, a patient with preserved color vision may not correctly distinguish colors. There is also simultaneous and letter agnosia. Diagnosis of such deviations requires a thorough examination by a neurologist. You can determine the type of agnosia using special tests.
The treatment of such a disease consists in the active therapy of the deviation that led to the defeat of individual parts of the brain. Very often, agnosia is not cured, causing great discomfort to the patient.
Visual defect typical of classic migraine
Migraine with typical aura is more common in males. In this case, patients may experience visual impairment. As a rule, they appear in the form of sparkling points, lightning-likeflashes, zigzags, balls, after which a rather severe attack of headache develops. The intensity of such phenomena is observed for several minutes or seconds. Quite often, sparkling images are replaced by the loss of some parts of the visual fields. It should be especially noted that such disorders are sometimes combined with numbness of the face, half of the body and tongue, as well as weakness in the limbs and impaired normal speech.
