Final answer:
Stereopsis is the ability to fuse two ocular images into one cerebral picture, involving convergence and the accommodation-convergence reflex. It is crucial for depth perception and three-dimensional vision.
Step-by-step explanation:
The ability to fuse two ocular images into one cerebral picture is called stereopsis or three-dimensional vision. This involves the coordination of both eyes to create depth perception and is related to several vision processes, including convergence, where the eyes move toward each other to focus on a nearby object, and conjugate gaze, where the eyes move together in the same direction. The optic nerve from each eye merges at the optic chiasm, allowing visual information to be combined in the brain, giving rise to a single integrated image with depth, enabling us to see the world in three dimensions.
When the eyes converge, they both adduct, and to maintain focus on an approaching object, the lens of the eye changes shape in a process called accommodation. This accommodation-convergence reflex is coordinated by neurological pathways involving the oculomotor nerve.