MRI — Pituitary Macroadenoma with Optic Chiasm Compression

A 45-year-old woman presents with a 3-month history of progressive visual disturbance described as "loss of the outer edges of my vision" and new-onset frontal headache. MRI of the sella turcica with gadolinium shows a 18 mm hypointense lesion arising from the anterior pituitary with superior extension. The structure marked **B** in the diagram shows compression of the crossing nasal retinal fibers. Which of the following visual field defects is most characteristic of this mass effect?