Which visual field defect is produced by damage to Meyer's loop in the left temporal lobe?

Which visual field defect is produced by damage to Meyer's loop in the left temporal lobe?

• A. Left inferior quadrantanopia
• B. Left superior quadrantanopia
• C. Right inferior quadrantanopia
• D. Right superior quadrantanopia

Answer: (D)

Damage to Meyer's loop in the left temporal lobe disrupts the part of the optic radiations that carries information from the contralateral upper visual field. Meyer's loop contains fibers that represent the upper portion of the field, and a lesion here produces a contralateral superior quadrantanopia—often described as a “pie in the sky.” So, with a left temporal lobe injury, the right superior visual field is lost in both eyes, yielding a right superior quadrantanopia. If the damage were in the parietal portion of the optic radiations, you’d expect a contralateral inferior quadrantanopia (pie in the floor). This distinction helps pinpoint why the right superior quadrant is affected in this scenario.

Damage to Meyer's loop in the left temporal lobe disrupts the part of the optic radiations that carries information from the contralateral upper visual field. Meyer's loop contains fibers that represent the upper portion of the field, and a lesion here produces a contralateral superior quadrantanopia—often described as a “pie in the sky.” So, with a left temporal lobe injury, the right superior visual field is lost in both eyes, yielding a right superior quadrantanopia.

If the damage were in the parietal portion of the optic radiations, you’d expect a contralateral inferior quadrantanopia (pie in the floor). This distinction helps pinpoint why the right superior quadrant is affected in this scenario.