A patient has an injury to the optic nerves, such that the branches of each optic nerve that normally cross to the opposite side of the brain at the optic chiasm are severed. The remaining branches, which do not cross to the other side of the brain, are intact. Which of the following best describes the effect of this injury on his vision?
A) He can now see only by using his right eye; his left eye is functionally blind.
B) Only information from the left visual field can enter his brain for processing.
C) Only the signal for half the visual field of each eye is processed by the brain.
D) His brain now receives visual information only from the medial half of each retina.

Question

Quizplus · Accepted Answer

The injury affects the crossing fibers at the optic chiasm, which carry information from the nasal (medial) halves of each retina. This results in loss of peripheral vision from both eyes, meaning only the temporal (lateral) halves of each retina, which do not cross, send signals to the brain.

A Patient Has an Injury to the Optic Nerves, Such