A 38-year-old woman with progressive visual loss from a large pituitary macroadenoma extending into the suprasellar cistern undergoes Humphrey perimetry. Which part of the visual field is expected to be affected FIRST?

• A Inferior temporal quadrants bilaterally
• B Temporal crescents bilaterally
• C Superior nasal quadrants bilaterally
• D Superior temporal quadrants bilaterally ✓

Explanation

A pituitary tumour compresses the chiasm from below, striking first the decussating fibres from the inferior nasal retinae, which travel in the lowest portion of the chiasm. These fibres represent the superior temporal quadrants, so bitemporal superior quadratic loss appears before complete bitemporal hemianopia. A craniopharyngioma compressing the chiasm from above preferentially involves the superior nasal retinal fibres and produces inferior temporal defects first, which is the key discriminating point.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.