The diagram shows the pathway of axons from the retina to the visual cortex. If a lesion interrupted the visual pathway at the black bar, a person would expect to see:
A)only the right visual field from both eyes.
B)only the left visual field from both eyes.
C)the right visual field from the left eye and the left visual field from the right eye.
D)the left visual field from the right eye and left eye and the right visual field from the right eye.

Question

The diagram shows the pathway of axons from the retina to the visual cortex. If a lesion interrupted the visual pathway at the black bar, a person would expect to see: 
A)only the right visual field from both eyes. 
B)only the left visual field from both eyes. 
C)the right visual field from the left eye and the left visual field from the right eye. 
D)the left visual field from the right eye and left eye and the right visual field from the right eye.

Quizplus · Accepted Answer

The axons from the nasal (medial) part of the retina cross at the optic chiasm to join the contralateral optic tract, whereas the axons from the temporal (lateral) part of the retina remain on the ipsilateral optic tract. Therefore, a lesion at the black bar would only affect the axons crossing at the optic chiasm, resulting in the loss of the left visual field from the right eye and right visual field from the left eye. This is known as a bitemporal hemianopia or heteronymous hemianopia.

The Diagram Shows the Pathway of Axons from the Retina