Ametropia
Summary/Definition
Ametropia is a situation in which the focus of the eye is not concentrated in the central region of the retina. In other words, the object we want to see is not in the focus of our eyes.
Astigmatism is a condition in which the eye cannot focus on one point due to the uneven refraction of light entering the eye due to the uneven surface of the cornea.
Myopia means that the eyeball is too elongated, and the focus that should be on the retina is in front of the retina, which makes it difficult to see objects clearly in the distance and to see objects clearly near.
Amblyopia is a condition in which vision deteriorates and cannot be corrected with optical correction, even if the eye has no visible abnormalities.
Symptoms
Ametropia usually causes difficulties with clear vision of objects. Depending on the severity, mild ametropia may be asymptomatic, while severe ametropia may lead to gradual deterioration of vision.
The most common symptom of myopia is the inability to clearly distinguish objects at a distance. Since objects that are close are usually clearly visible, this rarely leads to the development of amblyopia. However, if myopia is accompanied by astigmatism, asymmetric myopia or high-grade myopia, this may contribute to the development of amblyopia. Hyperopia can manifest itself in the form of various symptoms depending on the age, the amplitude of the accommodation of the eye and the object to be considered. With a sufficient amplitude of eye accommodation, mild hyperopia is often not accompanied by special visual symptoms, and in many cases there are no visual disturbances or objective deviations from the norm. However, as the degree of hyperopia increases, the control of the refractive power of the eye increases, there is a decrease in visual acuity, and eye pain and headaches may also occur due to accommodation fatigue.
A common symptom of astigmatism is that objects appear blurry rather than clear. In more severe cases, astigmatism may be accompanied by eye pain and headaches. Amblyopia is a condition in which the path of light and the optic nerve are normal, but visual acuity is reduced to such an extent that it is impossible to achieve normal vision using optical correction. There may also be a difference in visual acuity between the two eyes – more than two rows in the table to check visual acuity. In the presence of this symptom, it is necessary to conduct an examination to determine whether vision is developing normally.
Diagnostics
Ametropia can be detected by refractive examination. Usually, the degree of ametropy of the eyes is determined by objective refraction, and further correction and verification of visual acuity are carried out by subjective refraction. In some cases, the degree or presence of ametropia may vary depending on the accommodation of the eye, so sometimes eye drops are used to eliminate the accommodation spasm, and then refraction is performed.
Treatment and course of the disease
Treatment of ametropia is aimed at improving focus on the central fossa. Treatment options include the use of glasses, contact lenses and refractive surgery.
Concave lenses are usually prescribed for myopia, convex lenses for hyperopia, and cylindrical lenses for astigmatism. The appointment of glasses is considered the most convenient way to solve the problem of vision loss caused primarily by ametropia.
It is necessary to learn how to wear contact lenses correctly and take care of them, since improper handling of them can cause diseases of the cornea or conjunctiva. Orthokeratology is a method of correcting myopia, in which the shape of the cornea is temporarily changed with the help of special lenses that the patient uses at night, which allows him to do without glasses or contact lenses during the day.
Refractive surgery includes photorefractive keratectomy using an excimer laser and surgical implantation of an artificial lens. Laser refractive keratoplasty and photorefractive keratectomy are methods of reducing & increasing the refractive ability of the cornea by changing its curvature using a laser. Phakic implantation of an artificial lens is an operation to correct a refractive error, in which a special artificial lens corresponding to ametropia is installed, while preserving the intact lens.
