neuroq57 - spartans1

[ArchivalUser]

A 50 year old lady complains of gradual onset of blurred vision in her left eye. Examination reveals a left sided relative afferent pupillary defect. Fundoscopy reveals left sided optic atrophy. Visual fields show a left sided central scotoma and an upper quadrantic visual field defect in the right eye. Where is the lesion?
A. Left optic nerve
B. Left anterior optic chiasm
C. Sphenoid wing
D. Left occipital area
E. Left optic radiation

[ArchivalUser]

B........????

[ArchivalUser]

Answer: b) left anterior optic chiasm. Lesions of the anterior chiasm (junction of optic nerve and chiasm) will produce an ipsilateral central scotoma and a contralateral superior quadrantanopia. The contralateral defect is due to interruption of the crossing nasal fibers.