Question

If there is a lesion in the left optic nerve before the optic chiasm, how would vision be affected?

(A) All information from the right eye would be compromised.
(B) All information from the left eye would be compromised.
(C) All information from the right visual field would be compromised.
(D) All information from the left visual field would be compromised.

Answer 1

A lesion in the left optic nerve before the optic chiasm would lead to vision loss in the left eye, resulting in unilateral blindness or monocular vision loss.

Step-by-step explanation:

If there is a lesion in the left optic nerve before the optic chiasm, the visual consequence would be that all information from the left eye would be compromised. This is because the optic nerves carry visual information from their respective eyes to the brain, and if the left optic nerve is damaged, it cannot transmit visual signals to the brain. Visual information from the medial (nasal) side of the left retina crosses over at the optic chiasm to the right side of the brain, but since the lesion is before the chiasm, these axons would also be affected. The lateral (temporal) side of the left retina's axons, which do not cross and project to the same side of the brain, would be impacted by the lesion as well. As a result, the patient would experience a loss of vision in the left eye, known as unilateral blindness or monocular vision loss.