Correct! This is a right superior homonymous quadrantanopia—a defect pattern that is exquisitely localizing—to the left inferior visual cortex or its adjacent incoming axons. Notice three features of these defects: 1) they are on the same side of visual space (“homonymous”); 2) the defect borders are aligned to the vertical meridian (“hemianopic”); and 3) the defect borders are aligned to the horizontal meridian. Defects with borders aligned to BOTH MERIDIANS can arise only from lesions limited to the upper or lower banks of the calcarine fissure, a brain groove that separates the superior from the inferior primary visual cortex. In this patient, the lesion lies in the lower bank

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A Meyer’s loop lesion does cause a homonymous hemianopia, but the defect borders rarely reach down to the horizontal meridian. Instead, their inferior borders have a radial orientation with respect to the fixation point, forming defects popularly known as “pie in the sky”

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By the way, do not apply the term “quadrantanopia” unless the defects are homonymous hemianopias with borders aligned to both the vertical and the horizontal meridians! True quadrantanopias are almost always caused by infarctions in the domain of the posterior cerebral artery, which serves the upper and lower calcarine banks with separate branches. With regard to the other answer choices: optic tract lesions do not typically produce quadrantanopias, and optic chiasm lesions never do! In this patient, MRI revealed restricted diffusion in the lower left bank of primary visual cortex, indicating fresh infarction. The lower calcarine artery, one of the terminal branches of the posterior cerebral artery, must have been occluded. Embolism is always a consideration, with the heart as a source.

Incorrect

Incorrect

Incorrect