From what distance to check visual acuity

To visit an ophthalmologist must be at least once a year to avoid possible problems with vision. This event will not take much time, but the doctor will conduct all the necessary tests: test of visual acuity, fundus examination. And if necessary pick up points.

Instruction

1. A healthy eye has a visual acuity of 1.0. Visual acuity — the eye's ability to distinguish between two equidistant points at a minimum distance from each other. Determine this figure by using the table Sivtseva-Golovin, named after outstanding Soviet ophthalmologists. It is a white poster in the left part of which has black letters and the right black closed rings (Landolt rings). And letters, and a ring divided into 12 rows on size: the largest are on the top line, the smallest on the bottom. To the left of each row shows the figures indicating the distance at which healthy eyes should distinguish this line. On the right side shows the value that indicates the visual acuity for each row. The healthy eye sees the tenth row with distance of 5.0 meters.
2. Procedure visual acuity is as follows. The table is placed on the wall approximately at the level of human growth. Table lighting should be very good, otherwise possible distortion, giving the wrong information to the doctor. The patient is seated on a chair at a distance of five meters from the table. One eye (usually the left) closed the special flap, the other eye the patient examine table. To increase the speed of check visual acuity is often proposed to call only 1-2 letters from each row, and read out only the latest distinct rows. Then similarly, the left eye. Usually for simplicity of notation use the letter part of the table (table Sivtseva).
3. When using a table Sivtseva there is a risk of getting incorrect data, because the letters are always arranged in the same order, and to remember them is not difficult. This is especially important when conducting surveys in children (in order not to miss a decrease in visual acuity) and under the military-medical commissions. To this end, all the same more efficiently using a table Golovin with the Landolt rings. However, in modern ophthalmic practice, the most used development Sivtseva, as a more simple and understandable for the explanation and for reading.
4. In Russia it is accepted to measure visual acuity from a distance of 5.0 meters. It is believed that at this distance the eye is able to distinguish between those values that are accepted for the absolute visual acuity. There are two parallel sticks the letter "W" in the tenth line are located at a distance of 1.45 mm from each other. In foreign medicine vision is tested by Snellen table. This table is similar to table Sivtseva, but uses letters of the Latin alphabet. By the way, abroad decided to check vision from a distance of 6.0 meters, so the size of the letters there are different from the Russian version.