The working distance is the distance between the surgeon's eyes and the patient's mouth. First of all, to determine the normal working distance in the normal working state, the correct posture to ensure the surgeon comfortable, straight back, not too tilted. This process can be adjusted by someone else. You can also refer to the following table to help you know the best working distance: Height & lt;170 cm 170-190 cm >190 cm Sitting posture 340 mm 420 mm 500 mm Standing posture 420 mm 500 mm 550 mm