Visual pathway
Lesion site
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The visual pathway runs from each eye's retina, through the optic nerve, to the optic chiasm where roughly half the fibers cross to the opposite hemisphere, on through the optic tracts and radiations, and finally to the occipital cortex. Where a lesion sits along that route determines the exact shape of the resulting visual field defect — a rule neuro-ophthalmologists use every day to localize disease from a field test alone. This simulator renders the pathway as a real 3D anatomical schematic: pick a lesion site from optic nerve to occipital pole, adjust how complete the lesion is, and watch the matching segment glow while two live Goldmann-style field charts redraw the exact monocular or binocular defect — bitemporal hemianopia, incongruous homonymous hemianopia, a Meyer's-loop quadrantanopia, or a macula-sparing cortical hemianopia — with live percentage readouts for each eye.