Determining the visual acuity for distance
Examination of visual acuity is done by first testing one eye, while the other eye is closed at the time. The patient is required to read the optotypes that the eye sees to the bottom line, which is documented. The last line is written, and if the patient can read only a few signs from the next one, they are recorded as a plus. If, for instance, the patient sees 5 rows, his visual acuity is 6/12 in relation to the normal visus. If the patient sees 3 characters in the 6th row, it is written v = 6 / 12 + 3. If the patient clearly recognizes all the rows (visus 6/6) means that the patient sees normally (there is emetropy) or is easily farsighted (there is latent hypermetropy which is compensated by the accommodation).
The process of seeing is not pure mathematics, so a patient with a 6/12 visuity does not have a 50% visual acuity. The loss of visual acuity, i.e. of the central sight, is calculated according to the percentage of the drop of the sight of the examined eye (both eyes together). Thus for example 6/6, 6/5 and 6/4 represents a normal visible acuity. The visual acuity of 6/12 represents loss of vision of 15%, 6/60 loss of 80% and 6/24-loss of 40%.
If the patient does not see the uppermost order, we bring him closer to the board and record the distance from which he reads (for example, from 3 meters he reads what he should read from 60 meters or 3/60). If the patient does not read the signs from any distance, we stop at a certain distance and with an extended hand we point fingers with a question as to how much the patient will count. When the patient counts, we write BP. If he does not count the fingers, we wave our hand and check if the patient sees it. If he does not see the hand, we direct a light source from a 20 cm distance and check if there is a visual perception of light. If he notices the light, we note that there is a light perception. If there is no light perception, we note that it does not exist. In this case, it is diagnosed as blindness or amurosis.
optometrist Marija Kosturanova