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Updated: Dec 2, 2025
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Optic Disc Cupping Due to Dolichoectatic Internal Carotid Artery Optic Nerve Compression
Jonathan A Micieli1, Edward A Margolin
1Department of Ophthalmology and Vision Sciences (JAM, EAM), University of Toronto, Toronto, Canada ; Division of Neurology, Department of Medicine (JAM, EAM), University of Toronto, Toronto, Canada; and Kensington Vision and Research Centre (JAM), Toronto, Canada .
Summary
Compression of the optic nerve by the internal carotid artery (ICA) can cause optic neuropathy and cupping that mimics glaucoma, even without high intraocular pressure (IOP). This finding is crucial for diagnosing optic neuropathies.
Area of Science:
- Ophthalmology
- Neuroscience
- Radiology
Background:
- Investigating optic neuropathy caused by optic nerve compression from the internal carotid artery (ICA).
- Differentiating this condition from glaucoma in patients with normal intraocular pressure (IOP).
Observation:
- Retrospective case series of three patients with optic neuropathy and optic disc cupping.
- Patients presented with visual field defects and optic nerve cupping, but had IOP < 21 mm Hg.
- Radiological evidence confirmed optic nerve compression by the ICA in all cases.
Findings:
- Significant optic nerve compression by the ICA can lead to optic neuropathy.
- The condition presents with optic disc cupping and visual field defects, mimicking glaucoma.
- This occurs in patients without elevated IOP.
Implications:
- Highlights a non-glaucomatous cause of optic disc cupping and visual field loss.
- Emphasizes the importance of neuroimaging in diagnosing optic neuropathies.
- Suggests reconsidering differential diagnoses in suspected normal-tension glaucoma cases.
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