Question

Incongruous Homonymous hemianopia with Wernicke's hemianopia pupil is seen with the lesion of

• A. Optic radiation
• B. Lateral geniculate body
• C. Optic tract
• D. Anterior occipital cortex

Answer 1

The Correct Option is C

Localize by two clues: incongruity plus a pupillary defect both point upstream to the optic tract.
The more anterior (closer to the chiasm) a retrochiasmal lesion is, the more incongruous the homonymous hemianopia, because the corresponding fibres from the two eyes have not yet lined up. The optic tract is the most anterior post chiasmal site, so it gives the most incongruous defect.
Crucially, the pupillary light reflex fibres are still traveling within the optic tract here; they leave only just before the lateral geniculate body. A tract lesion thus produces a Wernicke's hemianopic pupil (no reflex when the blind hemiretina is lit) and, later, bow tie optic atrophy.
The optic radiation and occipital cortex lie beyond where pupillary fibres have departed, so their defects are congruous and spare the pupil. Combining an incongruous hemianopia with a hemianopic pupil pins the lesion to the optic tract.