Optics: diseases — симптомы, диагностика и лечение

Farsightedness, or hypermetropia, is an optical feature of the eye in which rays of light are collected conventionally behind the retina, and not on it: the eye is too short or its refractive power is too weak. The name confuses people: with noticeable hypermetropia, it is difficult to see both near and far, but a young man with a slight plus can freely read the bottom lines of the table, paying for it with a headache in the evening. Another common confusion is with the word “age-related”: hypermetropia and presbyopia are designed in completely different ways, although both sooner or later lead to reading glasses. And the main thing you should know right away: glasses do not spoil vision and do not “wean the eyes from working,” but in a child, uncorrected farsightedness can actually lead to strabismus and a persistent decrease in vision, which is then no longer lifted by the glasses.

Astigmatism is a condition in which the refractive surfaces of the eye, most often the cornea, are not perfectly spherical: they bend more in one direction than in another. Because of this, the light is collected not into one point, but into two different focal lines, and the brain receives an image stretched in one direction: the point turns into a stroke, the round headlight into an elongated spot, and the letters “O” and “C” become indistinguishable. Almost everyone has a slight astigmatism, and it does not require any action, but starting from about 0.75-1.0 diopters it already noticeably reduces the quality of vision and causes headaches. Children's age is especially important: if a child with astigmatism sees a blurry picture for years, the visual cortex simply will not learn to process a clear image, and amblyopia will develop, which is very difficult to correct after 8-9 years.

Anisometropia is a condition in which the optical power of the right and left eyes differs. One eye may be nearsighted and the other normal or farsighted, or the difference may be in the degree of astigmatism. A small discrepancy exists for many people and does not interfere in any way. But when the difference becomes noticeable, the brain receives two images of different clarity and size and cannot combine them. In adults, this manifests itself as visual fatigue and headaches, but in a child, the brain simply suppresses the signal from the worse eye - amblyopia, or “lazy eye,” develops. This is why it is important to detect anisometropia as early as possible.

Refractive errors are conditions in which the image is focused away from the retina and vision becomes blurry. These include myopia, farsightedness and astigmatism. These are not diseases of the eye in the usual sense, but features of its optics, and they are corrected with glasses, lenses or surgery. Childhood myopia deserves special attention: it progresses while the eye is growing, and modern ophthalmology can slow down this process - but only if it starts on time.

Asthenopia is visual fatigue that occurs with prolonged strain on the eyes: working at a computer, reading, driving, small manual work. The eyes get tired, burn, turn red, blurriness, heaviness and headache appear, often towards the end of the day. This is not a separate disease, but a signal that the visual system is working under strain. Common causes include ill-fitting or outdated glasses, hidden farsightedness and astigmatism, age-related presbyopia, weakness of the adductor muscles, and dry eye syndrome, which worsens with infrequent blinking at the screen. Asthenopia does not permanently damage vision, but it noticeably reduces performance. In most cases, it can be eliminated with proper vision correction, breaks and organization of the workplace.

Presbyopia is an age-related decrease in the eye's ability to see clearly at close range. To view a close object, the lens changes shape and becomes more convex; this process is called accommodation. Over the years, the lens thickens and loses elasticity, so after about 40–45 years a person begins to move the phone and book away, and in low light, small print becomes unreadable. Presbyopia develops in all people, it is not a disease, but a natural change, and it cannot be prevented by exercise. It can be easily corrected with glasses, contact lenses or surgery. The first appearance of complaints is a good reason to undergo a full examination by an ophthalmologist: after 40 years, the risk of glaucoma and other eye diseases increases.

Accommodation spasm is a persistent tension in the ciliary muscle of the eye, which is responsible for focusing near. When working with books, notebooks, phones and computers for a long time, the muscle stops completely relaxing, and the eye seems to get stuck in near vision mode. As a result, distance vision deteriorates, fatigue and headaches appear, and a routine test may show myopia, which in fact is not there. Therefore, the condition is called false myopia. Most often it occurs in schoolchildren and students, but it also occurs in adults with intense visual load. The spasm is reversible, but without eye rest and treatment it can contribute to the development of true myopia. An accurate diagnosis is made only after a vision test with pupil dilation.