A 62-year-old man presents with difficulty seeing food on his plate while eating. Visual field testing shows a left homonymous superior quadrantanopia with normal acuity and pupils. The lesion is most likely located in the:

• A Left temporal lobe involving Meyer's loop
• B Right parietal lobe involving the superior optic radiations
• C Right temporal lobe involving Meyer's loop ✓
• D Right lateral geniculate body

Explanation

Meyer's loop carries fibres from the contralateral superior quadrant, looping through the temporal lobe before reaching the calcarine cortex. Damage to the RIGHT temporal lobe therefore produces a LEFT homonymous superior quadrantanopia, classically called a 'pie in the sky' defect. The parietal lobe carries inferior quadrant fibres, so a parietal lesion gives an inferior quadrantanopia, which kills distractor B. Laterality must match the field defect, eliminating option A.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.