A lesion of the optic nerve may result in which visual defect?

A lesion of the optic nerve typically results in unilateral loss of vision because the optic nerve is responsible for transmitting visual information from one eye to the brain. When there is damage to this nerve, the visual signal from the affected eye cannot reach the brain effectively, leading to a significant reduction or complete loss of sight in that eye.

This condition is often referred to as "monocular vision loss," where only one eye's vision is impacted as the optic nerve deals with the information from just one side. The other options are not directly associated with a primary optic nerve lesion. For example, double vision usually relates to issues with the muscles or nerves controlling eye movements rather than the optic nerve. Color blindness is typically linked to cone dysfunction in the retina, not the optic nerve, whereas bilateral visual field loss suggests involvement of other pathways and structures beyond the optic nerve itself, like the optic chiasm or the visual cortices, which would not occur solely from a lesion in one optic nerve.