Refractory disorders are an ophthalmic disease in which a decrease in vision is associated with an abnormality in image focusing. The symptoms of pathology are blurred vision along with rapid eye fatigue against the background of performing visual work. In addition, discomfort from a headache with eye strain is possible. To diagnose refractive errors, visometry, refractometry, ophthalmoscopy, biomicroscopy and perimetry are used. Therapeutic tactics are reduced to the appointment of contact methods of optical correction. Modern treatment methods are represented by laser and refractive surgery.
Refractory disorders include myopia (myopia), hyperopia (hyperopia), astigmatism, and presbyopia.
Reasons for violation
Many causes contribute to the development of refractive errors, but it is far from always possible to establish the etiological factor. Hypermetropia is the result of an inhibition of eye growth. Under normal conditions, this is diagnosed during the newborn. Other forms of refractive errors and accommodation are associated with polyetiological pathologies, the main reasons for the development of which are:
- Anatomical feature of the structure of the eyes. In people with myopia, the elongated sagittal axis of the eyeballs is determined. In the presence of farsightedness, the anteroposterior axis in humans is shortened. A predisposing factor is also often a change in the refraction of the optical medium.
- The influence of hereditary predisposition. For example, myopia is a genetically determined pathology. In the presence of a dominant type of inheritance, this disease is characterized by a milder course and occurs later. A recessive form of pathology is characterized by an early onset, and, in addition, an unfavorable prognosis.
- The effect of excessive visual stress. Long visual work (whether reading along with watching TV or computer games) leads to spasms of accommodation. A decrease in the accommodative capacity of the eyes is a risk factor for the subsequent development of myopia.
Disruption of eye refraction in children also occurs. About it below.
Additional factors affecting the appearance of pathology
In addition to the above reasons, it is necessary to note the following factors affecting the development of such a pathology as refractive errors:
- The effect of infectious diseases. The myopic variant of clinical refraction is often the result of previous infections in the form of rubella, ophthalmic herpes, and so on. Impaired optical function is often caused by congenital toxoplasmosis.
- Another reason for the occurrence of such a disease is an organic change in the anterior ocular segment. Eye injuries along with keratitis, cicatricial changes and opacities of the cornea lead to a change in the radius of the lens. The failure of the trajectory of the light beam acts as a trigger factor for the occurrence of acquired astigmatism.
- The effect of metabolic disorders. Persons suffering from metabolic disorders are at risk of weakened accommodation. The highest likelihood of this disease is noted in patients with diabetes. This can be explained by the intense synthesis of sorbine.
What violation of refraction leads to the development of myopia? Primary weakness of accommodation and imbalance of convergence and accommodation.
Symptomatology
The clinical manifestation of refractive error is determined by its type. In the presence of myopia, patients complain of the vagueness of far-spaced images. When looking at a short distance, vision is not impaired. In order to improve perception, people squint their eyes. Long-term optical loads provoke the appearance of discomfort in the frontal and temporal region along with pain in the orbit and photophobia. Myopia creates difficulties when traveling on your own transport and when watching movies in a movie theater. Age-related changes lead to an improvement in the visometric indicator in the fourth decade of life.
Patients with this pathology note that their vision deteriorates only when reading or using a smartphone. Viewing a subject located far away is usually not accompanied by visual dysfunctions. At the first degree of farsightedness, the compensation mechanism provides good near vision. A high level of farsightedness is accompanied by optical dysfunction, which is not related to the distance to the objects in question. Visual impairment with age may indicate the development of presbyopia.
Diagnostics
The diagnosis is usually based on anamnestic data, and, in addition, on the result of an instrumental method of research and a functional test. For patients with a suspected refractive error, visometry is carried out using test lenses, as well as using skioscopy. Diagnosis usually includes the following studies:
- Computer refractometry, which is the main method for studying clinical refraction. With hyperopia, visual dysfunctions in patients are eliminated with the help of collecting lenses.
- Visometry. In the presence of myopia, decreased vision can vary widely. In the case of performing visometry according to standard methods using the Golovin table, visual dysfunction with hyperopia cannot be established.
- Ophthalmoscopy. During examination of the fundus in patients with myopia, myopic cones are found along with staphylomas and degenerative dystrophic changes in the macula. In the peripheral part of the retina, multiple round, and, in addition, slit-like defects can be visualized.
Refractive Disorders in Children
The difference in ocular refraction after birth can be quite large. Both myopia and severe hyperopia can develop. At the same time, the average value of a child’s refraction is within the limits of hyperopia, with a value of +2.5 - +3.5 diopters. The vast majority of infants have astigmatism, with indicators of at least 1.5 diopters.
During the first year after birth, at the time of increased emmetropization, the difference in refraction decreases significantly - refraction of hyperopia and myopia shifts to the values of emmetropia, while the astigmatism also decreases. The course of this process slows down a little during the time period of life from 1 to 3 years, after which the refraction in the overwhelming number of children is corrected, approaching the indicators of emmetropia.
What other diagnostic methods are used?
During the diagnosis of suspected refractive errors, the following research and diagnostic options may be additionally carried out:
- Ultrasound examination of the eyes. An ultrasound scan is performed to measure ocular parameters. In the presence of myopia, the elongation of the anteroposterior axis is determined, and in the case of farsightedness, its shortening is recorded. In the presence of a fourth degree of myopia, vitreous changes are often detected.
- Perimetry As part of this study, a narrowing of the angular space is observed, which is visible to the eye with a fixed gaze. For patients with astigmatism, loss of certain areas from the visual field is typical. For a detailed diagnosis of the central region of visible space, the Amsler test is used.
- Biomicroscopy of the eyes. In this study, a single erosive defect in the cornea is revealed. If the patient has hyperopia, it is often possible to visualize conjunctival vascular injection.
Next, we learn how the treatment of refractive errors is carried out, and which therapeutic methods are currently used most often.
Pathology treatment
The tactics of therapy are determined by the form of visual refraction disorders. Myopia patients are prescribed eyeglass correction using scattering lenses. In the presence of the first degree of myopia, the compensatory mechanism allows the use of contact lenses and glasses only when necessary. With the development of weak hyperopia, patients are prescribed glasses with collecting lenses exclusively for working at a short distance. Permanent use of glasses is prescribed in the presence of severe asthenopia. The use of contact lenses may have a less pronounced effect, which is largely due to the formation of a small image on the inner shell of the eyes.
For the treatment of presbyopia, in addition to correction lenses, collecting lenses having a spherical shape are prescribed. Patients with astigmatism are individually selected glasses that combine spherical and cylindrical lenses. Contact correction involves the use of a toric lens. Against the background of low effectiveness of spectacle correction, microsurgical treatment is prescribed, which is reduced to applying microcuts to the cornea. In the presence of the first degree of astigmatism, excimer laser correction is allowed. Against the background of a high degree of the disease, patients are prescribed implantation of phakic lenses.
Forecast
The prognosis for this disease is often favorable. Timely correction of optical dysfunctions allows for complete compensation.
Prevention
Specific methods of prevention have not yet been developed. As for non-specific preventive measures, they are aimed at preventing spasms of accommodation, and, in addition, to stop the progression of pathology.
This requires visual gymnastics, taking breaks while working at the computer or while reading books. It is equally important in the framework of prevention to also monitor the lighting. Patients in middle and old age are recommended to undergo an annual examination by an ophthalmologist. In this case, it is necessary to measure intraocular pressure and conduct visometry.