Emmetropia is a clinical refraction in which parallel rays are concentrated in the plane of the retina. At the same time, the human eye perceives objects very clearly, without using accommodation.
In the presence of this type of vision, a person has absolutely no pathological changes and disorders, however, at the age of about 40-45 years, certain difficulties arise with reading. This condition requires correction.
Definition
Emmetropia is a state of vision, characterized by the fact that transmitted light rays are focused by refraction exactly on the retina, provided it is completely relaxed. This is a completely normal manifestation, so a person very clearly sees even very distant objects.
Emmetropia of the eye occurs when the refractive power of the cornea and the axis of the eyeball are stabilized, which allows the luminous flux to accurately focus on the retina. With this phenomenon, a person has the most distinct vision.
He sees equally well near and far from himself. When reading, if the subject is located at a distance of about 30-33 cm, you need to make a minimum of effort, as a result of which the eyes get tired much later than in any other condition.
Emmetropia is a proportional refraction in which the ratio of refractive power to the axis of the eye is optimal. If the indicators deviate in any direction, ametropia occurs.
Emmetropization
Many patients who have been given this diagnosis are interested in what it is - eye emmetropia. A description of this condition suggests that this condition is considered normal, but requires the supervision of a doctor.
Emmetropization is the process of emmetropia, which is controlled by incoming signals. The mechanisms that control this process have not yet been precisely studied. Presumably, it is influenced by a genetic factor.
Emmetropization occurs as a result of ongoing active and passive processes. Passive processes consist in increasing to the required size of the eyes with the growth of the child. The active process implies mechanisms for regulating the length of the axis of the eyeball.
Emmetropia disorders
Disorders of emmetropia are called ametropia. In this case, light rays do not reach the retina. Ametropia is also called a violation of refraction and emmetropia. Such disorders include hyperopia, myopia and astigmatism. The ability of the eyes to focus the light flux on the retina is based on such anatomical features as:
- eyeball length;
- lens bend;
- bending of the cornea.
If the eye has an excessively long axis, the luminous flux is focused in front of the retina, which provokes the occurrence of myopia. If the light reaches the retina about focusing, then it is farsightedness.
Of great importance is also the bending of the cornea, since if it does not have an ideal spherical surface, then the light flux is refracted with irregularities and focuses rather unevenly, which provokes the occurrence of astigmatism. If the lens has an excessively curved shape, then this becomes the main cause of myopia, and if it is flat, then hyperopia.
What are the pathologies
Emmetropia is a higher visual acuity, which is considered the norm. A person with such indicators has very clear vision and sees objects well within 1.5 m without eye strain. However, it is worth noting that in some cases various kinds of violations can occur which include:
- physiological astigmatism;
- ametropia;
- amblyopia;
- myopia;
- farsightedness.
Astigmatism is an anomaly, which consists in the fact that the rays of the light flux gather at one point, as a result of which a circle forms on the retina. The larger it is in diameter, the less visual acuity. The depth of the lesion depends on the width of the pupil.
Ametropia is a disproportionate refraction in which the focus of the rays does not coincide with the retina. Emmetropia is a proportional refraction, and it belongs to the most perfect and harmless variety. Visual acuity in this case is 1.0 or more.
Myopia - the luminous flux is collected in front of the retina, resulting in a slightly blurred image. Such a person does not see well in the distance and well in the vicinity. With farsightedness, the picture is blurry as in fog.
Amblyopia is a serious pathology in which no light enters the retina, which can be due to cataracts, a throat on the cornea and irreversible disorders in the vitreous body.
Clinical picture
In the event of the occurrence of absolutely any disorders associated with the organs of vision, in addition, symptoms such as:
- difficulty distinguishing distant objects;
- protrusion of the eyeball;
- headache.
All this happens due to overfatigue of the optic nerve and requires diagnosis, as well as qualified treatment.
Diagnostics
Refraction can be determined after applying special means in the form of drops, since only in this case is it possible to obtain the most accurate information without distorting the result. In addition, you can detect deviations using special lenses. If objective methods for determining refraction are additionally required, then skioscopy and refractometry are used.
In a newborn child, it is very difficult to recognize the presence of deviations, so the examination is limited only to detecting the presence of visual functions.
How to maintain good vision
Emmetropia is a normal state of refraction, while the image is the clearest, and the range of vision is the largest, tending to infinity. However, it is worth remembering that over time, refraction can worsen, which is why you need to follow the recommendations of an ophthalmologist and periodically undergo examinations.
In order to maintain a healthy vision for a long time, it is necessary to take into account such aspects as:
- food;
- visual loads;
- stress
- mental stress;
- vitamins.
Nutrition is very important, as there must necessarily be a lot of foods rich in vitamins and nutrients in the daily diet. It is necessary to minimize the amount of stress, reduce visual and mental stress.