Question
A 65-year-old male presents with progressive binasal visual field loss. Imaging reveals a space-occupying lesion (SOL) in the brain, and he is currently under treatment.
Based on the visual field defect, which of the following is the most likely anatomical location of the lesion?
| A. |
Lateral compression of the optic chiasm
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| B. |
Right Optic tract
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| C. |
Left occipital cortex
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| D. |
Midline optic chiasm
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Show Answer
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Correct Answer » A
Explanation
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This MRI image shows a sagittal section of the brain with a space-occupying lesion (SOL) located near the optic chiasm, highlighted by a red circle.
The lesion compresses the lateral aspect of the chiasm, correlating with binasal hemianopia — a characteristic visual field defect caused by pressure on the uncrossed nasal fibers of both optic nerves.
Lateral compression of the optic chiasm
– Binasal hemianopia refers to the loss of nasal fields in both eyes.
– This pattern is rare and typically associated with:
– Bilateral lateral compression of the optic chiasm, most commonly by:
1. Bilateral internal carotid artery aneurysms
2. Lateral SOLs near the optic chiasm
This type of compression affects the uncrossed temporal retinal fibers, which carry input from the nasal visual fields.
