Description In the process of optometry, it is used to measure the distance between the eyes of the human eye and the height of the pupil to the bottom of the lens. Usage method: 1. Hang the device on the glasses and align the center point with the bridge of the nose 2. There are knobs on the right and left, and you can adjust the pupil height measurement by twisting 3. The upper edge of the measuring piece is aligned with the center point of the pupil, and the value of the ridge height is read out at the edge of the center point under the frame.