Ophthalmologist, using specialized equipment, can do a detailed diagnosis. Examination of visual acuity is one of the important components of the examination. After all, customers often care about the opportunity to see a "clear picture".
A general examination of vision includes the ability to see small details at a distance and near, defines the field of view, and shows the ability to correctly perceive colors. Examination of visual acuity is, in essence, the ability to distinguish between small parts. The test should include the definition of visual acuity for large and small distances.
Basic stages of verification:
- Sharpness at large and small distances;
- Definition of refraction;
- Definition of the field of vision;
- The ability to distinguish between colors.
When you need to check the visual acuity over long distances, a person displays a special table of characters or letters (with sizes from greater to smaller). Today, paper or projection tables are most often used (a special projector is directed to the vertical flat surface of the image). The patient's task is to correctly identify a character or a letter. Diagnosis involves determining visual acuity for the left and right eyes separately, for two eyes at once. For people with visual impairment, the use of corrective lenses is added.
Examination of visual acuity at short distances is extremely simple: it is necessary to read text written in different sizes. Children are offered definition of different drawings. When the primary diagnosis reveals a deviation from the norm, the ophthalmologist is taken to study the exact causes of vision impairment.
Definition of refraction
When the visual acuity check is carried out, one of the stages of further diagnosis is the definition of refraction, that is, the correction forces of the lens to correct visual acuity. Errors of refractive nature are associated with the diffraction of the rays: they converge in a beam before or behind the retina, and not exactly on it. For people who already use lenses or eyeglasses, the definition of refraction is an indispensable step.
Definition of the field of view
The peripheral vision is verified by studying the field of view, that is, the entire area covered by the motionless eye. The closer to the center, the more clearly visible the objects, the further - the less clearly.
Ability to distinguish between colors
The ability to distinguish between colors is determined by special tests. One of the important tasks is the detection of color blindness (or color blindness), which is possible in diseases of the optic nerve or retina, hereditary predisposition.
It is necessary to pay attention to the fact that the examination should be carried out exclusively by the ophthalmologist, since adequate and correct definition of visual acuity, field of vision, ability to distinguish between colors, refraction is possible only with the use of special diagnostic equipment and the instructions of the doctor. It is advisable to conduct a complete visual examination every two years.