At the optic chiasm, which statement is true?

At the optic chiasm, which statement is true?

• A. All visual information crosses to the opposite hemisphere.
• B. Contralateral visual field information from the lateral retina projects to the ipsilateral brain.
• C. No information crosses; each eye stays in its own hemisphere.
• D. Visual information is processed entirely in the optic nerve.

Answer: (B)

The key idea is how the visual pathways reorganize at the optic chiasm. Fibers from the nasal halves of the retinas cross to the opposite side, while fibers from the temporal (lateral) halves stay on the same side. This means the left visual field from both eyes is processed in the right hemisphere, and the right visual field from both eyes is processed in the left hemisphere. In other words, contralateral visual field information ends up in the opposite hemisphere due to crossing at the chiasm, with subsequent processing continuing in the brain rather than in the optic nerve itself.

The key idea is how the visual pathways reorganize at the optic chiasm. Fibers from the nasal halves of the retinas cross to the opposite side, while fibers from the temporal (lateral) halves stay on the same side. This means the left visual field from both eyes is processed in the right hemisphere, and the right visual field from both eyes is processed in the left hemisphere. In other words, contralateral visual field information ends up in the opposite hemisphere due to crossing at the chiasm, with subsequent processing continuing in the brain rather than in the optic nerve itself.