This instrument is mainly used to check the power of the phoria prism of the human eye, (adding a single prism can expand the inspection range) is one of the necessary instruments for diagnosing abnormal eye positions.Inspection range: 0△~20△ (△ is the power of the prism), and the value of each division is 1△). Operation methodHold the handle 1 of the instrument with your hand, align the index reticle on the rotating prism 2 with the "0" reticle on the reading ring 3 (hereinafter referred to as "zero"), and then stare at the light bulb 3-5 meters away in front at the same time. Light source (ordinary flashlight can be used as light source).Then one eye leans against the end face of the Maldives rod frame 4 to observe the point light source through the instrument, and the other eye directly observes the point light source. At this time, what one eye sees is a bright red ray, and what the other eye sees is a spot of light source.If the light does not pass through the point of light, there is phoria in both eyes. At this time, turn the small handwheel 5 until the bright red light passes through the light spot, and then read on the reading ring. The value read is the prism power of the phoria to be checked.After zeroing, place the instrument in front of the left (right) eye according to the vertical position of the stripe groove of the Maldives rod. At this time, what the left (right) eye sees is a horizontal bright red light, and what the right (left) eye sees is light from the light source. point.If the light spot is above (below) the bright red light, it means left eye phoria; otherwise, it means right eye phoria. Turn the small handwheel 5 until the bright red light passes through the light spot of the light source. Then take a reading on the reading ring. 20 prisms, large viewing hole Inspection range 20△ Portable cryptic tester can measure the position of the near and far eyes