Binocular vision (lat. - bini for double, and oculus for eye) — the ability to clearly see the image with both eyes;
It creates stereopsis. If binocular vision does not develop, it may by only by the right eye or by the left eye. This is called a monocular vision. Maybe alternate vision: by the right eye, then the left eye - alternating monocular vision.
Sometimes there is a vision with two eyes, but without merging into a single visual image - at the same time. Absence of binocular vision with two eyes open outwardly manifested in the form of a gradually developing strabismus.