Compressive Optic Neuropathy

Key Points at a Glance

Highlights of This Disease

• Compressive optic neuropathy is caused by mass lesions such as tumors, aneurysms, cysts, or enlarged extraocular muscles in thyroid eye disease compressing the optic nerve.
• Common compression sites include the orbital apex; causes include thyroid eye disease, sino-orbital optic neuropathy, lymphoma, granulomatosis with polyangiitis, and hypertrophic pachymeningitis.
• Chiasmal lesions typically cause bitemporal hemianopia, most often due to pituitary adenoma.
• Dysthyroid optic neuropathy occurs in 3–8.6% of thyroid eye disease cases, with about 70% being bilateral.
• Visual field testing (Humphrey perimeter) and MRI (coronal and axial views are important) are key for diagnosis.
• The principle of treatment is surgical removal of the causative lesion, requiring a multidisciplinary approach.
• Relieving compression can improve visual function, but recovery is limited if optic atrophy has progressed.

1. What Is Compressive Optic Neuropathy?

Compressive optic neuropathy is a general term for optic nerve damage caused by compression of the optic nerve. Masses include tumors, aneurysms, hematomas, abscesses, and cysts.

Compression at any site along the optic nerve can cause compressive optic neuropathy. Common compression sites include the orbital apex, with causes such as thyroid eye disease, sino-orbital optic neuropathy, hemangioma, lymphoma, granulomatosis with polyangiitis (Wegener’s granulomatosis), and hypertrophic pachymeningitis. At the chiasm, pituitary adenoma is the most common cause, while craniopharyngioma is more frequent in children.

The pattern of visual field loss varies greatly depending on where along the visual pathway the compression occurs. It is clinically very important to infer the location of the lesion from the visual field defect pattern.

Dysthyroid optic neuropathy is one of the most severe symptoms of thyroid eye disease. It results from increased orbital pressure due to enlargement of extraocular muscles and orbital fat, compressing the optic nerve. In the worst case, it can lead to blindness, but early diagnosis is important because appropriate treatment can restore visual function. It occurs in 3–8.6% of thyroid eye disease cases, with about 70% being bilateral.

The incidence of orbital tumors in Japan is shown below.

Benign (top 5)	Proportion	Malignant (top 3)	Proportion
Idiopathic orbital inflammation	20%	Malignant lymphoma	Most common
Pleomorphic adenoma	13%	Lacrimal gland carcinoma	—
Hemangioma	13%	Metastatic tumor	—
Dermoid cyst	10%	—	—
Reactive lymphoid hyperplasia	10%	—	—

Q What is the most common cause of compressive optic neuropathy?

A

At the chiasm, pituitary adenoma is the most common cause. At the orbital apex, thyroid eye disease is most common, followed by idiopathic orbital inflammation, pleomorphic adenoma, and hemangioma. In children, craniopharyngioma is frequent.

2. Main symptoms and clinical findings

Subjective symptoms

Typically presents with slowly progressive unilateral visual loss. However, pituitary apoplexy or aneurysm rupture can cause acute onset. Visual field defects include concentric constriction or paracentral scotoma.

• Visual loss: Usually unilateral. Rarely, acute bilateral visual loss may occur.
• Dark areas in visual field: Patients may not notice temporal visual field defects.
• Headache: Often associated with increased intracranial pressure
• Eye pain / periorbital pain: Due to traction of the trigeminal nerve or dural stretching
• Diplopia: Caused by ocular motility disorders due to a mass
• Seizures: May occur with intracranial lesions
• Endocrine symptoms: Associated with pituitary lesions near the optic chiasm

Clinical Findings (Findings Confirmed by Physician Examination)

Characteristic findings according to the site of compression are shown below.

Orbital Lesions

Proptosis: The most representative finding.

Optic disc edema: Appears early, and progresses to pallor/atrophy as the condition advances.

RAPD: Relative afferent pupillary defect is observed.

Choroidal folds: Caused by compression of the globe by the mass.

Opticociliary shunt vessels: Actually represent retinochoroidal venous collateral pathways.

Features in thyroid optic neuropathy: Proptosis is not necessarily severe. Visual acuity loss ranges from mild to no light perception, but more than half maintain visual acuity of 0.5 or better. Decreased flicker value and color vision abnormalities are observed. RAPD positive (if unilateral or asymmetric).

Chiasmal Lesions

Bitemporal hemianopsia: A classic finding caused by compression of crossing nasal fibers. Often presents as asymmetric incomplete hemianopsia.

Junctional scotoma: Central scotoma in the affected eye plus contralateral superior temporal visual field defect, suggesting anterior chiasmal lesion.

Band atrophy of the optic nerve: In the chronic phase, pallor of the temporal and nasal central optic disc.

Postchiasmal Lesions

Optic tract: Incongruous homonymous hemianopsia plus RAPD. Near the cerebral peduncle, may be accompanied by contralateral hemiparesis.

Temporal lobe: Homonymous superior quadrantanopia (“pie in the sky”). Reflects damage to Meyer’s loop.

Parietal lobe: Homonymous inferior quadrantanopia (“pie on the floor”). May be associated with Gerstmann syndrome or hemispatial neglect.

Occipital lobe: Congruous homonymous hemianopsia. Macular sparing may be present.

In compressive optic neuropathy, the optic disc initially swells, and with delayed treatment progresses to pallor and atrophy. Optical coherence tomography (OCT) detects localized thinning of the inner retinal layers corresponding to visual field defects.

In compressive optic neuropathy due to sphenoid fibrous dysplasia, a glaucoma-like cupping of the optic disc has been reported, with OCT showing thinning of the retinal nerve fiber layer (RNFL) in all quadrants and diffuse loss of the ganglion cell layer⁵⁾.

Q What other visual field defect patterns occur besides bitemporal hemianopsia?

A

In the anterior chiasm, junctional scotoma (central scotoma in the affected eye plus contralateral superior temporal defect) or Traquair’s junctional scotoma (monocular hemianopic defect) occur. Posterior to the chiasm, homonymous hemianopsia or quadrantanopia appear depending on the compression site. In orbital apex lesions, concentric visual field constriction or paracentral scotoma may occur.

3. Causes and Risk Factors

The causes of compressive optic neuropathy are classified according to the site of compression along the visual pathway.

Orbital Tumors

• Intraconal: Cavernous hemangioma, optic nerve sheath meningioma, schwannoma, rhabdomyosarcoma, etc.
• Extraconal: Lymphoma (most common malignant), metastatic tumors (breast cancer, lung cancer common in adults), lacrimal gland tumors, invasion of sinus tumors, etc.
• Intercompartmental: Lymphangioma, neurofibroma (plexiform/diffuse), capillary hemangioma, etc.

Orbital apex lesions (inflammatory/infiltrative)

• Granulomatosis with polyangiitis (Wegener’s granulomatosis): Systemic vasculitis that affects the orbital apex and compresses the optic nerve.
• Hypertrophic pachymeningitis: Thickening of the dura around the orbital apex and optic canal compresses the optic nerve. Usually not visible on standard MRI; contrast-enhanced MRI is required.
• Thyroid eye disease (thyroid optic neuropathy): Enlargement of extraocular muscles and orbital fat increases intraorbital pressure, compressing the optic nerve at the orbital apex. Occurs in 3–8.6% of thyroid eye disease cases.

Intracranial / near the optic chiasm

• Neoplastic (common): Pituitary adenoma (most common), craniopharyngioma, meningioma²⁾, optic glioma.
• Neoplastic (rare): Chordoma, germ cell tumor, leukemia, lymphoma, metastatic disease.
• Non-neoplastic: Sinus mucocele (sphenoid/ethmoid sinus), arachnoid cyst, Rathke’s cleft cyst, fibrous dysplasia.

Vascular

• Aneurysm: Anterior communicating artery aneurysm, internal carotid artery aneurysm. May enlarge after flow diverter placement⁸⁾.
• Pituitary apoplexy: Causes acute visual field defects.
• Cavernous hemangioma / AVM: Impair the visual pathway through both compression and ischemia.

Postchiasmal Lesions

In adults, vascular and ischemic causes are common. In children, neoplastic causes are more common.

• Hemorrhage: Hypertensive hemorrhage, cerebral amyloid angiopathy, vascular malformations
• Primary brain tumors: Glioma, astrocytoma, oligodendroglioma
• Metastatic tumors: Commonly from lung, breast, and melanoma

Other Causes

• Infections: Infection of a paranasal sinus mucocele ¹⁾, hydatid cyst ⁹⁾ (consider in endemic areas)
• Sinonasal undifferentiated carcinoma (SNUC): Highly aggressive and can cause bilateral optic nerve compression ⁶⁾
• Nasopharyngeal carcinoma: Invades the orbital apex and compresses the optic nerve. Bilateral involvement is rare but has a poor prognosis ⁷⁾
• Pneumosinus dilatans: A rare condition in which abnormal expansion of the sphenoid sinus narrows the optic canal ¹⁰⁾

Signs Requiring Attention

If unexplained vision loss or visual field abnormalities are present, perform imaging to rule out compressive lesions. Acute bilateral vision loss may indicate a paranasal sinus mucocele or malignancy.

4. Diagnosis and Testing Methods

Visual Field Testing

Humphrey automated perimetry (24-2, 30-2, 10-2) is recommended for all patients with unexplained visual impairment. The pattern of visual field loss helps estimate the site of compression and guides imaging decisions.

Visual field testing is also useful for assessing disease progression and treatment efficacy, and should be performed over time.

Imaging Diagnosis

Imaging Modality	Advantages	Main Indications
CT	Excellent for detecting bone lesions, calcifications, and bone destruction	Orbital bone lesions, surgical planning
MRI	Optimal for soft tissue evaluation. Gold standard.	Tumor characterization, optic nerve evaluation
PET/CT	Detection of systemic metastases	Staging of malignant tumors

T2-weighted MRI is useful for differentiating tumor characteristics. Solid tumors (e.g., lymphoma, meningioma) appear hypo- to isointense, while vascular and cystic tumors (e.g., cavernous hemangioma, dermoid cyst) appear hyperintense. Dynamic contrast-enhanced MRI is also useful; cavernous hemangioma typically shows delayed enhancement.

In evaluating orbital apex lesions, selection of imaging plane is important. Optic nerve compression (apical crowding) due to thyroid eye disease and other conditions is assessed on coronal sections. Optic nerve stretching is assessed on axial sections. In orbital apex lesions, the anatomy around the optic nerve is dense, so lesions may be difficult to detect, requiring caution. Inflammatory dural thickening in hypertrophic pachymeningitis is not visualized without contrast-enhanced MRI.

Blood Tests

• CEA: Levels above 5.0 ng/mL suggest a high possibility of metastatic tumor.
• IgG4: Useful for differentiating IgG4-related disease.
• sIL-2R, LDH, β2-microglobulin: Markers for systemic dissemination of malignant lymphoma.
• Endocrine tests: Performed when pituitary adenoma is suspected.

OCT

Optical coherence tomography (OCT) detects localized thinning of the inner retinal layers and is useful for early detection of mild optic atrophy. It can detect abnormalities earlier than visual field testing. It also helps in estimating prognosis after treatment.

Differentiation from Glaucoma

Compressive optic neuropathy can present with glaucomatous-like optic disc cupping ⁵⁾. The following findings suggest a non-glaucomatous etiology:

• Age under 50 years
• Headache or periorbital pain
• Visual field defect respecting the vertical meridian
• Rapid visual loss
• Pallor disproportionate to cupping
• Asymmetric visual acuity loss and visual field defects

A report indicates that 6.5% of patients diagnosed with normal-tension glaucoma had clinically significant intracranial compressive lesions ⁵⁾.

Q How is glaucoma differentiated from compressive optic neuropathy?

A

Glaucoma typically presents with arcuate scotomas along the horizontal nerve fiber bundle, while compressive optic neuropathy is characterized by visual field defects respecting the vertical meridian. Pallor disproportionate to cupping, rapid vision loss, and onset before age 50 suggest a compressive lesion. Neuroimaging should be performed if suspected.

5. Standard Treatment

Treatment Principles

Most mass lesions compressing the visual pathway require surgery for both diagnosis (pathological confirmation) and treatment (relief of mass effect). Multidisciplinary collaboration (ophthalmology, neurosurgery, otorhinolaryngology, endocrinology, etc.) is essential depending on the cause.

Treatment by Cause

• Pituitary adenoma: Surgery is first-line except for prolactinomas, which are primarily treated with medications such as bromocriptine or cabergoline. Other brain tumors may require radiation therapy in addition to surgery.
• Orbital tumors: Complete surgical excision is standard for benign tumors. Pleomorphic adenoma of the lacrimal gland has a high recurrence rate with simple enucleation.
• Malignant lymphoma: Highly radiosensitive. Approximately 30 Gy for localized orbital disease, and 40 Gy for moderate to high-grade malignancy.
• Infiltrative optic neuropathy (e.g., leukemia): Leukemic cells are highly radiosensitive, and radiation therapy is first-line. Early initiation can rapidly improve optic neuropathy.
• Metastatic tumors: Hormone therapy may be effective for breast and prostate cancer. Systemic chemotherapy is also used.
• Thyroid eye disease (dysthyroid optic neuropathy): First-line treatment is steroid pulse or half-pulse therapy. After 1–3 courses, switch to oral prednisolone. Rapid tapering should be avoided as it may cause recurrence of optic neuropathy. Orbital decompression is performed for steroid-resistant cases. With appropriate treatment, over 70% recover visual function.
• Paranasal sinus mucocele: Emergency endoscopic sinus surgery for decompression is first-line ¹⁾⁴⁾. Initial visual acuity is an important prognostic factor ¹⁾.
• Fibrous dysplasia: Surgical decompression is considered in cases of symptomatic optic nerve compression. The indication for surgery in asymptomatic cases is controversial⁵⁾.

Prognosis

When compression of the optic chiasm is relieved, improvement in visual acuity and visual field can be observed. However, if optic atrophy is already evident, the visual prognosis is poor. Measurement of retinal thickness by OCT is useful for estimating prognosis after treatment.

In compressive optic neuropathy, a delay in intervention of 7 to 10 days or more is said to increase the risk of irreversible visual impairment⁴⁾.

Precautions in Treatment

• Steroid administration exceeding a total dose of 8 g in prednisolone equivalent increases the risk of acute liver injury.
• Malignant lymphoma also shrinks to some extent with steroids, so do not judge it as benign based solely on shrinkage.
• Exclude infectious lesions before steroid administration (may worsen fungal infection foci).
• Radiation exceeding 30 Gy increases the risk of radiation cataract, retinopathy, and optic neuropathy.

Q Will vision recover if optic nerve compression is relieved?

A

Relief of compression can be expected to improve visual acuity and visual field. However, recovery is limited if optic atrophy has progressed. The better the initial visual acuity, the better the prognosis. In thyroid optic neuropathy, approximately 70% or more recover visual function with appropriate treatment.

6. Pathophysiology and Detailed Mechanism

Anatomy of the Visual Pathway and Fiber Course

The visual pathway follows: retinal ganglion cells → optic nerve → optic chiasm → optic tract → lateral geniculate nucleus (LGN) → optic radiation → striate cortex (V1).

At the optic chiasm, nasal retinal fibers cross to the opposite side, while temporal retinal fibers do not cross and proceed ipsilaterally. Nasal fibers process the temporal visual field, and temporal fibers process the nasal visual field. Therefore, compression of crossing fibers causes temporal visual field defects, and compression of non-crossing fibers causes nasal visual field defects.

The Wilbrand knee (a structure in which contralateral inferonasal retinal fibers enter the ipsilateral optic nerve slightly before crossing) has been proposed as a cause of junctional scotoma, but its existence is debated.

Optic radiation and cortical correspondence

The optic radiation emerges dorsally from the LGN and divides into two bundles.

• Inferior fiber group (Meyer loop): Loops around the temporal lobe and transmits information from the upper visual field. Temporal lobe lesions cause homonymous superior quadrantanopia.
• Superior fiber group (parietal bundle): Passes through the deep parietal lobe and transmits information from the lower visual field. Parietal lobe lesions cause homonymous inferior quadrantanopia.

The tip of the occipital cortex (macular representation area) receives dual blood supply from the middle cerebral artery and posterior cerebral artery, so macular sparing can occur with damage to a single vascular territory.

Mechanisms of optic nerve damage

Multiple mechanisms are involved in the development of compressive optic neuropathy¹⁾.

• Direct compression: Physical displacement of the optic canal by a mass causes axonal damage.
• Blood flow impairment: Disruption of blood supply to the optic nerve due to compression.
• Inflammatory spread: Infectious contents of a mucocele directly spread to the optic nerve sheath.

Regarding the pathology of thyroid optic neuropathy, since visual acuity and visual field defects improve immediately after orbital decompression surgery, compression is inferred to be the main cause, but mechanisms such as ischemia and inflammation are also considered.

The effect of tumors on the optic chiasm involves both direct compression and inflammatory blood flow impairment.

In temporal lobe lesions due to compressive lesions, the visual field defect shows a gradual isopter pattern compared to vascular lesions.

Blood flow to the LGN is supplied by the anterior choroidal artery and posterior choroidal artery. Segmental homonymous visual field defects occur depending on the site of damage to each small artery.

7. Latest Research and Future Prospects (Investigational Reports)

For Patients: Please Read Carefully

The following content is currently at the research stage or under clinical trial and is not standard treatment available at general hospitals. It is reference information for professionals regarding future medical developments.

Treatment of Thyroid Eye Disease Compressive Optic Neuropathy with Teprotumumab

Teprotumumab (IGF-1R inhibitory monoclonal antibody) is the first approved drug for thyroid eye disease. Patients with compressive optic neuropathy (CON) were excluded from clinical trials, but efficacy in mild CON cases has been reported.

Chiou et al. (2021) reported two cases of mild CON due to thyroid eye disease that were resistant to IV steroids; after teprotumumab administration, visual field defects completely resolved in both cases ³⁾. In the first case, resolution was confirmed after the third dose, and in the second case after the second dose.

Management of Aneurysm Enlargement After Flow Diverter Placement

Tsuei et al. (2022) reported a case of a 17 mm supraclinoid internal carotid artery aneurysm treated with a flow diverter (Pipeline embolization device). Despite complete angiographic occlusion, the aneurysm enlarged and caused compressive optic neuropathy ⁸⁾. Microsurgical optic nerve decompression plus aneurysm coagulation and shrinkage improved the visual field.

Endoscopic Transnasal Optic Nerve Decompression (ETOND)

Zhou et al. (2024) performed endoscopic transnasal optic nerve decompression (ETOND) in four adolescent patients (mean age 12.75 years, all male) with visual impairment due to pneumosinus dilatans of the sphenoid sinus ¹⁰⁾. All cases were resistant to steroid pulse therapy, but visual improvement was achieved after ETOND.

Treatment Limitations of Compressive Optic Neuropathy Due to Malignancy

Kong et al. (2022) reported a case of bilateral orbital apex infiltration by nasopharyngeal carcinoma leading to no light perception ⁷⁾. Despite steroids, chemotherapy, and radiotherapy, the right eye had no light perception and the left eye only hand motion. The optic nerve is considered to have the lowest recovery rate among cranial nerves ⁷⁾.

Hydatid Cyst in Endemic Regions

Haydar et al. (2024) reported a case of a 22-year-old male from Afghanistan with a hydatid cyst in the inferior rectus muscle causing compressive optic neuropathy ⁹⁾. Complete excision and long-term albendazole therapy restored vision from 20/200 to 20/20.

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8. References

1. Che SA, Lee YW, Yoo YJ. Compressive optic neuropathy due to posterior ethmoid mucocele. BMC Ophthalmol. 2023;23:426.
2. Teng Siew T, Mohamad SA, Sudarno R, et al. Unilateral proptosis and bilateral compressive optic neuropathy in a meningioma patient. Cureus. 2024;16(2):e53728.
3. Chiou CA, Reshef ER, Freitag SK. Teprotumumab for the treatment of mild compressive optic neuropathy in thyroid eye disease: a report of two cases. Am J Ophthalmol Case Rep. 2021;22:101075.
4. Deb N, Neena A, Sarkar S, et al. Bilateral compressive optic neuropathy secondary to sphenoid sinus mucocele mimicking bilateral retrobulbar neuritis. Saudi J Ophthalmol. 2021;35:368-370.
5. Kiyat P, Top Karti D, Esen Ö, Karti Ö. Sphenoid bone dysplasia: a rare cause of compressive optic neuropathy mimicking glaucoma. Turk J Ophthalmol. 2023;53:70-73.
6. Hassan MN, Wan Hitam WH, Masnon NA, et al. Compressive optic neuropathy secondary to sinonasal undifferentiated carcinoma in a young male. Cureus. 2021;13(10):e19042.
7. Kong Y, Ng GJ. Rare early presentation of bilateral compressive optic neuropathy with complete vision loss from nasopharyngeal carcinoma. BMJ Case Rep. 2022;15:e248902.
8. Tsuei YS, Fu YY, Chen WH, et al. Compressive optic neuropathy caused by a flow-diverter-occluded-but-still-growing supraclinoid internal carotid aneurysm: illustrative case. J Neurosurg Case Lessons. 2022;4(1):CASE22139.
9. Haydar AA, Rafizadeh SM, Rahmanikhah E, et al. Orbital intramuscular hydatid cyst causing compressive optic neuropathy: a case report and literature review. BMC Ophthalmol. 2024;24:257.
10. Zhou X, Xu Q, Zhang B, et al. Sphenoidal pneumosinus dilatans associated compressive optic neuropathy: a case series of four adolescent patients. Heliyon. 2024;10:e38763.