Where is the lesion in the visual pathway?

[Miracoli]

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A 30 yrs old woman presents to the ER complaining of blurred vision, pain in the right eye and decreased visual acuity in the right eye that does not correct with pinhole testing. There is a relative afferent pupillary defect on the right, and testing of the right visual field shows a small central scotoma. The most likely localization of the lesion is the:
A. Optic nerve
B. Optic chiasm
C. Optic tract
D. Optic radiations
E. Occipital cortex

 

[notbobtrustme]

scotoma + loss of afferent makes me lean toward optic nerve.

none of the others fit, given they would show some sort of gross visual field defect. All we have here is an apparent scotoma.

 

[syma]

Optic neuritis. Therefore A

 

[Apoplexy__]

Yeah, A. Besides optic neuritis, could be glaucoma (esp. in ER setting).

 

[sanj238]

Why not macular degeneration

 

[Transposony]

Yeah, A. Besides optic neuritis, could be glaucoma (esp. in ER setting).

Glaucoma would have peripheral scotoma.

 

[Transposony]

Why not macular degeneration

Young women, Pain & afferent pupillary defect

 

[sarah65]

I'd say A as well. Pain, visual acuity and defect afferent limb were key for me.

 

[syma]

Young women, Pain & afferent pupillary defect

And no pain with AMD.

With CAG, you would get a scotoma after a period of time. Not everyone with a closed angle attack presents with a scotoma.

 

[Miracoli]

A is correct!
-Decreased visual acuity that does not correct with pinhole testing, an RAPD, and a central scotoma is characteristic of optic nerve disease.
-A lesion affecting the optic chiasm will produce a bitemporal heteronymous hemianopia.
-If a lesion affects the optic tract, the optic radiations (in both temporal and parietal areas), it will produce a contralateral homonymous hemianopia
-If a lesion affects the occipital cortex, it will produce a contralateral homonymous hemianopia with “macular sparing.”

 

[Transposony]

Pinhole Testing