Neuro-Ophthalmology and Orbit Flashcards

A pituitary macroadenoma compressing the chiasm from below most typically causes which early field defect?

Answer: Bitemporal superior quadrantanopia

Compression from below first affects inferonasal crossing fibers, which serve the superotemporal fields.

A patient has a central scotoma in the right eye and a superotemporal field defect in the left eye. Where is the lesion?

Answer: Junction of the right optic nerve and chiasm

A junctional scotoma comes from a lesion where the optic nerve meets the chiasm, involving contralateral inferonasal crossing fibers.

A right temporal lobe lesion affecting Meyer's loop causes which visual field defect?

Answer: Left superior homonymous quadrantanopia

Meyer's loop carries inferior retinal fibers for the contralateral superior field, which gives a 'pie in the sky' defect.

Macular sparing in a homonymous hemianopia from an occipital infarct is most often attributed to which factor?

Answer: Dual blood supply to the occipital pole from PCA and MCA

Collateral flow from the MCA to the occipital pole often preserves macular vision in PCA infarcts.

A left optic tract lesion with an incongruous right homonymous hemianopia is most likely to cause an RAPD in which eye?

Answer: Right eye

The RAPD is in the eye with temporal field loss (contralateral), because crossed fibers outnumber uncrossed fibers.

A patient with a known pituitary adenoma develops sudden severe headache, bilateral vision loss, and ophthalmoplegia. What is the most likely diagnosis?

Answer: Pituitary apoplexy

Hemorrhage or infarction of an adenoma causes acute chiasmal and cavernous sinus compression and needs urgent steroids and neurosurgical review.

Which pattern of optic atrophy is classic for a lesion of the optic tract or chiasm?

Answer: Band (bow-tie) atrophy

Loss of nasal-retina crossing fibers causes nasal and temporal 'bow-tie' pallor of the disc.