Anchor the exam on whether the defect is monocular, bitemporal, or homonymous, because that determines where to image. A clear field pattern is more useful than vague symptom wording when deciding whether the lesion is optic nerve, chiasm, or occipital cortex.

Bitemporal hemianopia localizes to the optic chiasm; A central scotoma in one eye usually indicates pre-chiasmal retina or optic nerve disease; Left homonymous hemianopia localizes to the right retrochiasmal pathway; Macular sparing classically suggests occipital infarction; Palinopsia points to posterior cortical dysfunction