Optometry glasses must be checked for visual acuity, and those who finish single vision know this. Many years ago, opticians were accustomed to checking monocular vision, and there were few spectacle shops that could check binocular vision. With the progress of the times, people can no longer be satisfied with only looking at monocular vision.

The fundamental difference between monocular vision and binocular vision is that monocular vision is two-dimensional planar vision, while binocular vision is three-dimensional stereo vision, which is an advanced vision function for humans. With normal binocular vision, humans can learn better, engage in more delicate work, and correctly judge the distance, size, position, direction of objects, and the positional relationship between themselves and the objective environment.

Binocular vision must be based on finish single vision, but there are qualitative differences between them. Of course, compared with the spectacle shop that can only check monocular vision, the professional level and the quality of glasses are different from those that can check binocular vision.

Normal binocular vision refers to the image of an external object that falls on the macula or other corresponding points of the eyes, and at the same time produces nerve impulses, which are transmitted by the nervous system to the visual center of the brain. The optic center transmits the nerve impulses from the two eyes. The signal is analyzed and integrated into a complete, single-dimensional image.

Therefore, although it is binocular vision, the final image is a single object, so normal binocular vision is usually called binocular monovision.

The abnormal function of binocular monovision can be divided into two categories: one is that due to some reason, the normal binocular monovision function is not formed during the development process; the other is that the formed binocular monovision function is damaged. There are many factors that affect the function of binocular monovision, the more common reasons are:

①The large anisometropia causes the disparity in the size and definition of the image of the two eyes to be too large to form binocular monovision.

② Due to some eye diseases, the visual acuity of the two eyes is too different.

③ Abnormal adjustment and convergence ratio cause strabismus, or abnormality of one or several extraocular muscles makes the eyeballs unable to coordinate movement and form strabismus. The strabismus can not simultaneously see or merge.

④ When neurasthenia patients are exposed to external stimuli, they may also affect the formation of finish single vision.