A 42-year-old woman with a pituitary macroadenoma undergoes visual field testing. The earliest field defect expected from upward compression of the chiasm by this tumour is:

• A Superotemporal quadrantic defects
• B Inferotemporal quadrantic defects ✓
• C Binasal defects
• D Left homonymous hemianopia

Explanation

Fibres from the inferior nasal retina cross low in the anterior chiasm and are compressed first by a tumour rising from below, so pituitary adenomas produce inferotemporal field defects initially, later becoming complete bitemporal hemianopia. A craniopharyngioma compresses the chiasm from above and damages upper crossing fibres first, giving superotemporal defects, which makes option A the classic distractor here.

Reference: Parsons' Diseases of the Eye, 23rd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.