Stereo vision refers to the ability of human eyes to distinguish the distance, depth, concave convex and height of surrounding objects in three-dimensional visual space. Stereopsis is an advanced visual function, which is closely related to daily life, study and work. Stereopsis examination is of great significance to evaluate visual function. Stereopsis function is developed independently. It is not completely affected by vision development. Generally, stereopsis is basically mature at the age of about 3-4 years. However, there will be differences in stereopsis acuity among different people. The basis of stereo vision is binocular monocular vision. In clinic, some people can accurately judge the distance even if they lose one eye since childhood. This is a phenomenon of Monocular Stereo Vision, which judges the spatial position through training and relying on experience and some specific conditions. For amblyopia patients, stereopsis function examination is to comprehensively evaluate the visual function of patients and provide guiding value for the training of work orientation and living ability of patients.

All inspection methods of binocular stereopsis are designed based on the principle of binocular parallax. Because the horizontal distance between the two eyes is about 60mm, when the two eyes look at the same object, the pointing angle of the two eyes' line of sight to the object is different due to the collection factors, and there are certain differences in the corresponding relationship between the two eyes' retinas, resulting in certain differences in the two eyes' images. This phenomenon is called binocular parallax. Binocular stereopsis is a subjective examination. Therefore, the examination of binocular stereopsis needs the cooperation of the examinee. The unit of dioptric radian is usually dioptric radian and sometimes diopter（ ˋ） Unit, 1 ˋ= 60〝.

Stereoscopic examination methods mainly include Dorman depth vision meter examination, stereoscope examination, synoptophore examination, comprehensive optometer examination, Titmus stereogram examination, Frisby board stereogram examination, random point stereogram examination, etc. The common stereoscopic inspection methods usually include: Titmus stereogram inspection, Frisby board diagram inspection, random point stereogram inspection, comprehensive optometer stereogram inspection and so on.