Compressive Optic Neuropathy: Overview
- Optic nerve or chiasm damage from compression by an intraorbital or intracranial mass
- Common orbital causes: Graves disease, sino-orbital tumor, optic nerve sheath meningioma
- Common intracranial causes: sphenoid meningioma, craniopharyngioma, pituitary adenoma, pilocytic astrocytoma (optic glioma), carotid aneurysm
- Treatment often reverses vision loss, especially if diagnosis is made early
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Core clinical features
- Visual acuity and visual field loss in one eye or both
- Nerve fiber bundle and/or hemianopic visual field defects
- Afferent pupil defect if the optic nerves are affected asymmetrically
- Optic discs appear normal, elevated, or pale
- Visual loss is usually slowly progressive, although acute loss may occur, especially with tumor hemorrhage and cyst expansion
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Possible accompanying clinical features
- Periocular pain
- Proptosis
- Resistance to retropulsion of the eye
- Ptosis
- Displacement of the eye within the orbit
- Ocular ductional deficits
- Conjunctival congestion
- Neurologic or endocrine abnormalities
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Imaging features
- MRI shows an orbital mass or an intracranial mass compressing the optic nerve and/or optic chiasm
- Optic neuritis
- Radiation optic neuropathy
- Posterior ischemic optic neuropathy
- Hypotensive ischemic optic neuropathy
- Leber hereditary optic neuropathy
- Toxic optic neuropathy
- Nutritional deficiency optic neuropathy
- Infiltrative optic neuropathy
- Order an orbit-based MRI, which will provide adequate views of the anterior visual pathway and disclose most causative lesions, but…
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Trap: intraorbital optic nerve sheath meningiomas or other compressive lesions may go undetected because imaging signs are too subtle to be seen on standard brain imaging protocols or if contrast is not used
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Trap: intracranial vascular lesions are often poorly characterized or even undetected unless dedicated vascular imaging is performed and reviewed by experienced radiologists
- Refer the patient to a specialist experienced in treating orbital or intracranial tumors
- Surgery is indicated only if vision is compromised or the tumor is large or enlarging and surgery is considered safe
- Radiation therapy is indicated only if the patient is aged greater than 9 years and surgery would be unsafe or has left a large or expanding tumor
- Endovascular intervention may be indicated for carotid aneurysm
- Visual recovery depends on the degree of pre-existing vision loss, the nature of the lesion, and the expertise of the treating physicians