A macular involving visual field defect will occur only if which arteries are damaged?

• A. Only posterior cerebral artery is damaged
• B. Only anterior cerebral artery is damaged
• C. Both posterior cerebral artery and middle cerebral artery are damaged
• D. None of the above

Answer: (C)

Macular vision occupies a large cortical area in the occipital lobe and relies on blood supply from both the posterior cerebral artery and, near the foveal representation, the middle cerebral artery. Because of this dual supply, damage confined to the posterior cerebral artery often produces a contralateral homonymous hemianopia with macular sparing, since the middle cerebral territory can still perfuse the central retina. Only when both vascular territories are compromised does the central macular portion lose its cortical input, resulting in a macular-involving visual field defect. So concurrent damage to both the posterior cerebral artery and the middle cerebral artery explains a macular involvement.