EH-1 (Hess Screen) is a diagnostic device used to test eye muscle coordinometry. Testing with EH-1 is based on the detection of a false location for the action of the paralysed muscle. The test is most commonly used in paralytic strabismus and muscle paralysis and paresis. EH-1 takes the form of an array – a graph of intersecting parabolic lines of a strictly fixed shape, forming a grid. At the intersection of the lines, 25 test points in the form of green LEDs were applied. The patient’s task is to indicate individual points displayed in random order by the doctor.