What occurs at the optic chiasm?

What occurs at the optic chiasm?

• A. Partial decussation of the optic nerve fibers.
• B. No crossing of fibers.
• C. Complete decussation of all optic fibers.
• D. Crossing occurs only for left eye fibers.

Answer: (A)

At the optic chiasm, the nasal retinas’ fibers cross to the opposite side while the temporal retinas’ fibers stay on their own side. This partial crossing means information from the left visual field (which hits the nasal retina of the left eye and the nasal retina of the right eye) is routed to the right hemisphere, and vice versa. Because only some fibers cross (the nasal ones), the crossing is partial, not complete. This arrangement supports binocular integration and contralateral processing of visual fields.

At the optic chiasm, the nasal retinas’ fibers cross to the opposite side while the temporal retinas’ fibers stay on their own side. This partial crossing means information from the left visual field (which hits the nasal retina of the left eye and the nasal retina of the right eye) is routed to the right hemisphere, and vice versa. Because only some fibers cross (the nasal ones), the crossing is partial, not complete. This arrangement supports binocular integration and contralateral processing of visual fields.