Parietal lobe lesions typically cause which type of visual field defect?

• A. Superior VF defects
• B. Inferior VF defects
• C. Central scotoma
• D. Quadrantanopia

Answer: (B)

When a parietal lobe lesion targets the dorsal optic radiations, it disrupts fibers that carry information from the inferior part of the visual field. Because of the way the visual field is mapped onto the retina and then through the optic radiations, damage in one parietal lobe leads to a loss in the contralateral inferior visual field. That’s why inferior visual field defects are the typical pattern with parietal lobe involvement. If the lesion is localized along the radiations, you might see an inferior quadrantanopia; a broader field loss can occur with a larger lesion. Central scotomas point to macular or retinal involvement, not this pathway, and superior visual field defects point to temporal lobe/Meyer’s loop issues.