Which statement best explains macular sparing in PCA strokes?

Which statement best explains macular sparing in PCA strokes?

• A. Macula is spared due to dual blood supply from MCA and PCA
• B. Macula is spared because retina has separate supply from choroidal arteries exclusively
• C. Macula is never spared
• D. Macula sparing occurs due to optic nerve involvement

Answer: (A)

Macular sparing in PCA strokes occurs because the central visual cortex region that processes the macula has collateral blood flow from the middle cerebral artery in addition to its primary supply from the posterior cerebral artery. When a PCA infarct damages the occipital cortex, peripheral parts of the visual field lose function, producing a contralateral homonymous hemianopia, but the macular area remains perfused via MCA branches, preserving central vision. This dual vascular supply to the occipital pole explains why central vision can be spared despite a PCA stroke. The phenomenon is cortical, not due to the retina or optic nerve.

Macular sparing in PCA strokes occurs because the central visual cortex region that processes the macula has collateral blood flow from the middle cerebral artery in addition to its primary supply from the posterior cerebral artery. When a PCA infarct damages the occipital cortex, peripheral parts of the visual field lose function, producing a contralateral homonymous hemianopia, but the macular area remains perfused via MCA branches, preserving central vision. This dual vascular supply to the occipital pole explains why central vision can be spared despite a PCA stroke. The phenomenon is cortical, not due to the retina or optic nerve.