Diagnosis of visual impairments is a procedure that is necessary for every person. Ideally, the diagnosis of visual impairments should be carried out once a year in order to timely identify the disease at the initial stage of its development.
Diagnosis of visual impairment involves an analysis of the ability of the human eye to clearly see objects located in the distance and near the eyes, as well as an assessment of the field of view and the ability to distinguish colors.
To diagnose visual impairments, a person is usually shown tables consisting of a set of numbers, letters or other symbols of different sizes. The table can be fixed to the wall or displayed on it using a symbol projector. The patient must establish which letters, symbols and numbers are shown to him. First, visual acuity is checked in each individual eye, when the patient is asked to cover one eye with his hand, and the other to try to see the symbols. Then visual acuity is checked in both eyes at once, when it is necessary to look with two eyes. If a person uses means of vision correction – contact lenses or glasses, then vision is checked both without them and with them. To diagnose visual impairments near the distance, it is necessary to read a text fragment, which is printed in letters of different fonts.
If the result of the diagnosis of visual impairment showed reduced vision, then the task of the eye doctor is to establish the cause of the impairment of vision, for which he can prescribe an analysis of the patient’s refraction.
The study of human refraction is the identification of the optical intensity of corrective means for vision, which are necessary for a person in order for him to be able to see normally. Errors in the study of refraction can occur under the condition of focusing light rays not at the very center of the retina, on a little behind it or in front of it. Diagnosis of visual impairment necessarily includes a refraction study if a person wears glasses or contact lenses.
Diagnosis of visual impairment, during which the characteristics of the visual field are determined, consists in the assessment of peripheral vision. The field of view of the eye is the area that a person is able to see in a particular direction of the eyes. Accordingly, a person sees objects in the center of the field of view more clearly, and at the periphery they are vague and indistinct.
Diagnosis of visual impairment for color perception is carried out to establish color blindness – a violation of color perception – in patients who have suspicions of pathology of the retina or optic nerve. In addition, color perception tests are routinely performed on those patients who have a genetic predisposition to color blindness.
How often is it necessary to undergo the procedure for diagnosing visual impairments
Eyesight tests should be done regularly. If no visual impairment is observed in a person, then the diagnosis of visual impairment should be carried out according to a specific schedule:
– almost immediately after the birth of the child;
– a child aged six months;
– when the child reaches the age of three;
– before entering school and annually during training;
– every two years between the ages of twenty and sixty-five;
– annually after sixty-five years.
These conditional periods, described in the diagram, are of the nature of recommendations, that is, it is advisable to observe them for people who have no problems with the work of the visual organs. If any deviations from normal vision develop, more frequent visits to the ophthalmologist may be assigned. The visit schedule is indicated by the ophthalmologist.