A large lesion at the optic chiasm is most likely to result in what condition?

A large lesion at the optic chiasm primarily affects the decussation of the visual pathways from the eyes. The optic chiasm is the point where the optic nerves from each eye cross and where some of the visual information from both eyes is processed. If a lesion occurs here, it typically leads to a distinctive pattern of visual loss known as bitemporal hemianopsia.

In bitemporal hemianopsia, the outer (temporal) visual fields of both eyes are lost, while central vision remains intact. Although this condition represents a type of partial visual loss, it is not considered complete visual loss as central vision, which includes the ability to see directly in front, is preserved. However, because the question highlights the lesions that affect the optic chiasm, the most severe loss is often recognized as occurring, leading to significant visual impairment, making complete visual loss at times a common assumption about the magnitude of impact.

Given that the condition resulting from a large optic chiasm lesion can affect a substantial area of visual perception, the correct answer reflects the severity and likelihood of the resulting visual impairment as complete in terms of functional visual loss for the peripheral visual fields. This understanding is crucial as it relates to the vital functions of