R homonymous hemianopsia is caused by a lesion on which lobe?

Homonymous hemianopsia is a visual field defect that results in the loss of half of the visual field on the same side in both eyes. This condition occurs when there is damage to the optic pathways in the brain, particularly in areas responsible for processing visual information.

The occipital lobe is the primary region involved in visual processing. Specifically, it is responsible for interpreting signals from the eyes and transforming them into visual perception. A lesion in the occipital lobe can disrupt the transmission of visual information from the contralateral (opposite side) visual field, leading to a corresponding loss of vision in both eyes—resulting in homonymous hemianopsia.

In contrast, lesions in the frontal, temporal, and parietal lobes may lead to different deficits or symptoms, but they are not generally the primary causes of homonymous hemianopsia. The occipital lobe's crucial role in visual field processing is what makes it the correct answer to this question.