Infarctions within the territory of the posterior cerebral artery typically lead to what visual deficit?

• A. Complete blindness in one eye
• B. CL homonymous hemianopsia with macular sparing
• C. Loss of central vision
• D. Color vision deficiency

Answer: (B)

Infarctions in the territory of the posterior cerebral artery (PCA) can result in specific visual deficits due to the areas of the brain that the PCA supplies. One of the hallmark deficits associated with PCA strokes is contralateral homonymous hemianopsia, which manifests as the loss of the visual field on the same side in both eyes. This means that if the right PCA is affected, the left visual field is lost in both eyes, and vice versa.

The "macular sparing" component of this deficit is particularly important to note. Macular sparing refers to the preservation of the central visual field or the foveal region, which is responsible for sharp vision and color perception. This preservation occurs because the central retina receives blood supply from both the PCA and the middle cerebral artery (MCA), allowing for some redundancy. As a result, when the PCA is occluded, the foveal vision can often remain intact, leading to the classic presentation of contralateral homonymous hemianopsia with macular sparing.

Understanding this visual deficit is crucial for diagnosis and management of patients with PCA infarctions, and it highlights the unique vascular anatomy of the visual pathways in the brain.