Continuing Education Activity

Optic nerve sheath meningiomas (ONSM) are rare benign tumors of the central nervous system originating from the meninges encasing the optic nerve. Despite being histologically low-grade and slow-growing, their location affects the anterior visual pathway, potentially leading to significant and often irreversible vision loss if not promptly identified and addressed. The treatment of ONSM is complicated by its proximity to the optic nerve, as surgical excision frequently poses a significant risk of blindness in the affected eye. Consequently, radiotherapy has become the primary treatment modality in most cases. However, meticulous patient selection and monitoring are essential.

This activity outlines the pathophysiology, epidemiology, clinical presentation, diagnostic approaches, and optic nerve sheath meningiomas management. The activity includes describing the distinctive imaging features on magnetic resonance imaging and the significance of sophisticated functional imaging techniques using positron emission tomography. Pertinent literature regarding observation, radiotherapy, and restricted surgical methods can help clinicians evaluate risks and benefits when managing patients. This activity highlights the importance of the interprofessional healthcare team, which comprises ophthalmologists, neuro-ophthalmologists, neurosurgeons, radiation oncologists, radiologists, and rehabilitation specialists, in enhancing diagnostic precision, refining treatment, facilitating visual rehabilitation, and improving overall patient outcomes.

Objectives:

• Assess clinical symptoms, visual function, and neuroimaging findings to establish disease extent and progression.
• Implement current evidence-based treatment options for patients with optic nerve sheath meningiomas.
• Identify the signs and symptoms that warrant surgical intervention to avoid permanent visual loss in patients with optic nerve sheath meningiomas.
• Collaborate and communicate effectively within the interprofessional healthcare team—including ophthalmologists, neurosurgeons, radiation oncologists, radiologists, and rehabilitation specialists—to coordinate diagnostic evaluation, treatment planning, and visual rehabilitation for optimal patient outcomes.

Introduction

Optic nerve sheath meningioma (ONSM) is a rare, typically benign tumor originating from the meningothelial cells encasing the optic nerve.[1][2] Despite sharing histologic resemblance to meningiomas in other intracranial locations, the anatomical positioning of ONSM within the optic canal and orbit leads to a unique clinical presentation and therapeutic approach.[3][4] These tumors account for approximately 2% of all orbital tumors and 1% to 2% of all intracranial meningiomas; however, they can significantly jeopardize vision due to their proximity to the optic nerve and its vascular supply.[5] Consequently, even small tumors can cause significant visual impairment, differentiating ONSM from other orbital lesions whose size is more closely associated with symptom severity.

The optic nerve is surrounded by meninges continuous with the cerebral membranes, comprising the dura mater, arachnoid mater, and pia mater. ONSMs arise from arachnoid cap cells within the sheath, typically in the intraorbital or intracanalicular segments. Tumors can disseminate circumferentially around the nerve or migrate posteriorly down the optic canal towards the optic chiasm, jeopardizing vision bilaterally and worsening prognosis.[6] Exophytic or segmental growth patterns occasionally displace rather than encase the nerve, impacting surgical feasibility and planning. These dissemination patterns are essential for clinical decision-making, especially with radiation planning or surgical decompression.

Imaging advancements have revolutionized the diagnosis and monitoring of ONSM. High-resolution orbital MRI is the gold standard, showing the characteristic tram-track appearance (see Image. Optic Nerve Sheath Meningioma). Axial postcontrast scans are often pathognomonic.[7] Computed tomography may reveal calcifications, which support the diagnosis in equivocal cases.[8] Functional imaging techniques such as somatostatin receptor (SSTR)–based positron-emission tomography (PET/CT) or single-photon emission computed tomography have been used, leveraging the expression of somatostatin receptor subtype 2 (SSTR2) in meningiomas.[9] These approaches are especially beneficial when standard MRI yields equivocal results, frequently eliminating the necessity for biopsy, which poses risks in this area.

Optical coherence tomography (OCT) is a noninvasive tool for evaluating optic nerve fiber layer thinning and macular ganglion cell complex loss.[10] These changes are associated with visual field abnormalities and can serve as objective indicators of progression or stabilization during treatment. The multimodal integration of imaging and functional assessment underscores the contemporary methodology for ONSM: accurate diagnosis, vigilant monitoring, and prompt treatment upon evidence of progression. The dissemination patterns hold both clinical and therapeutic significance.

The natural history of ONSM is typically indolent, characterized by gradual yet progressive visual deterioration. Without treatment, the condition often results in irreversible optic atrophy and blindness in the affected eye. However, some patients experience sudden or rapid vision loss, indicating that not all cases follow the typical gradual progression.[11] Intraorbital ONSMs typically manifest with proptosis, optic disc pallor, and progressive vision impairment. Intracanalicular tumors can cause earlier and more severe vision deterioration due to the restricted bony constraints around the optic nerve. Posterior extension into the optic chiasm increases the likelihood of contralateral vision impairment, necessitating expanded radiation fields and an interdisciplinary evaluation of risks and benefits.[6]

Consequently, tumor localization and growth orientation awareness are crucial for accurate prognosis and treatment planning. ONSM illustrates how a tumor with a low histologic grade can cause significant morbidity due to its anatomical position. The characteristic imaging finding is circumferential optic sheath enhancement on MRI, and untreated cases virtually inevitably lead to significant vision impairment. Understanding these characteristics and awareness of novel imaging techniques and therapeutic strategies is essential for comprehensively managing this uncommon yet clinically meaningful orbital neoplasm.[12]

Etiology

ONSM originates from arachnoid cap cells that line the meninges of the optic nerve.[5] The specialized cells involved are the same progenitors associated with meningiomas in the central nervous system, indicating that ONSM shares biological characteristics with intracranial meningiomas; however, it exhibits a distinct clinical presentation due to its orbital position. The intraorbital portion is the most common site of origin (approximately 92%). Approximately 95% of ONSMs are unilateral, but rare bilateral tumors tend to occur in patients with neurofibromatosis type 2 (NF2).[13][14] 

The tumor typically occurs sporadically, lacking a distinct identifiable etiology, and is most often classified as World Health Organization grade 1.[15] In contrast to optic nerve glioma, which originates from glial components within the nerve, ONSM is extra-axial and compresses the optic nerve rather than invading it. Hormonal factors have been implicated in the etiology of meningiomas, including ONSM. Expression of progesterone receptors is commonly observed in orbital meningiomas, and experimental evidence indicates that progestins may promote tumor proliferation.[16] Clinical data suggest that women are more frequently affected, and tumor growth has occasionally been observed to accelerate during pregnancy.[17] While a direct causative relationship remains unproven, these study results indicate a hormonal influence on tumor biology. Recent pharmacoepidemiologic investigations have identified a correlation between prolonged exposure to high-dose progestins and an increased risk of meningioma, leading to recommendations for monitoring or discontinuing these medications in individuals with diagnosed meningiomas.[18][19]

Genetic disorders also contribute to ONSM in specific instances. For example, NF2 is the most common tumor predisposition syndrome, defined by the presence of numerous schwannomas and meningiomas. Pediatric ONSMs, although uncommon, are more frequently associated with NF2, and bilateral orbital involvement should prompt genetic assessment.[20]  Germline NF2 mutations and somatic NF2 inactivation promote tumorigenesis and are commonly associated with more aggressive clinical behavior than sporadic ONSM.[21] NF2 is caused by a mutation in the gene that normally encodes the protein merlin (schwannomin), located on chromosome 22. NF2 follows an autosomal dominant inheritance pattern, and individuals are born with one mutated copy of the NF2 gene.

Environmental exposures, trauma, or previous irradiation have not been consistently associated with ONSM, although cranial irradiation during childhood is a recognized risk factor for meningiomas overall.[6] Inflammation has been postulated as a contributing factor, but lacks corroborative evidence. Case reports occasionally describe ONSM association with unrelated orbital or systemic conditions; however, causality remains conjectural. Molecular research has significantly enhanced the understanding of meningiomas in general; however, studies specific to ONSM remain limited. Progress in DNA methylation profiling and genomic sequencing has revealed biologically distinct subgroups with variable prognoses.[22]

The clinical significance of these molecular classes remains uncertain, but investigation in this field may enhance risk assessment and targeted therapies. In summary, the pathogenesis of ONSM is multifactorial, characterized by sporadic growth from arachnoid cap cells, possible hormonal influences, and infrequent correlations with hereditary disorders such as NF2. Although most cases are idiopathic, recognizing these etiologic factors is crucial for identifying at-risk populations and counseling women of reproductive age and those with tumor predisposition syndromes.

Epidemiology

Optic nerve sheath meningioma is an uncommon orbital tumor, representing approximately 2% of all orbital neoplasms and less than 1% to 2% of all intracranial meningiomas.[14][23] Although rare, ONSM has clinical significance due to its propensity to cause irreversible visual impairment. ONSM predominantly affects adults, with most patients in their fifth to seventh decades of life. Of all meningiomas that involve the orbit, only 10% are of primary orbital origin, while the remainder are intracranial in origin and extend into the orbit.[14] Unlike optic pathway gliomas, which primarily occur in children, ONSMs are typically lesions that manifest in adults. This distinction is diagnostically pertinent when assessing optic nerve tumors across various age demographics. Pediatric occurrences are rare, are usually linked to syndromic diseases such as NF2, and tend to be more aggressive.[24][25] Pediatric ONSM has an overall prevalence of between 1:95,000 and 1:525,000.[26] Approximately 5% to 6% of cases are bilateral and associated with NF2.[14]

A notable sex disparity exists, with women more frequently affected than men, at ratios between 3:1 to 6:1 in several cohorts.[6] The female predominance corresponds with the hormonal explanations proposed in meningioma pathogenesis, particularly involving progesterone receptor expression.[27] Nonetheless, epidemiologic studies' results report that sex-based risk is multifactorial and may potentially reflect referral and diagnostic biases.

Geographic studies indicate that ONSM is globally prevalent with similar demographic patterns; however, regional disparities in diagnostic resources affect the reported incidence. In high-income countries, the widespread use of MRI and enhanced orbital imaging has enabled earlier detection. In contrast, in resource-limited environments, patients may present at a later stage with more advanced disease.[5] Population-based studies, such as those in the United States Surveillance, Epidemiology, and End Results program, yield the most dependable incidence estimates; however, they likely underestimate actual prevalence due to underdiagnosis or misclassification.[12] Results from recent studies have also emphasized socioeconomic disparities. Access to specialized neuro-ophthalmology care affects diagnostic timelines and treatment outcomes. Diagnostic delays correlate with poorer visual prognosis, highlighting that epidemiology encompasses not only biological predisposition but also the framework of health care systems.[11]

Pathophysiology

These tumors arise from the meningeal cells (arachnoid cap cells) lining the optic nerve sheath.[23] They typically grow circumferentially around the optic nerve and can significantly compress its pial vascular supply. This anatomical shape causes a gradual narrowing of the nerve fibers, resulting in compromised axoplasmic transport, ischemia, and ultimately axonal degeneration. These tumors can invade the entire path of the optic nerve, from the optic canal posteriorly to the globe anteriorly.[28][29]

Even small tumors can cause considerable dysfunction due to the limited capacity for expansion within the optic canal and intraorbital region. One of the initial alterations in ONSM is the cessation of axoplasmic flow. The optic nerve compression impedes the transfer of cellular organelles and proteins along the axons. This obstruction presents clinically as enlargement of the optic disc, which may advance to pallor and atrophy as axonal degeneration occurs.[6]

Tumor growth causes dural thickening and calcification, producing a rigid sheath that further jeopardizes the nerve. Radiologically, this presents as the tram-track sign on MRI or discernible calcifications on CT. Pathophysiologically, this signifies continuous remodeling of the meningeal tissue that perpetuates optic nerve damage.[5] ONSM can compromise vision by mechanical compression, axoplasmic stasis, ischemia, and subsequent death of retinal ganglion cells. These processes progress gradually, making prompt diagnosis crucial. Although the majority of tumors are indolent and low-grade, their anatomical position makes them dangerous, as even minimal proliferation can result in blindness.

Secondary ONSM is an extension of an intracranial meningioma into the orbit. A secondary ONSM is more common than a primary ONSM, but it is not a true ONSM as it does not grow from the cells surrounding the nerve. Some meningiomas can grow en plaque along the temporal dura and extend into the orbit through the optic canal or the superior orbital fissure.

Histopathology

ONSMs have microscopic characteristics similar to meningiomas found in other intracranial regions; however, they reveal unique patterns attributable to their orbital positioning. Histologically, most are characterized as meningothelial (syncytial) or transitional meningiomas of World Health Organization grade 1.[30] Their structure consists of homogeneous polygonal cells organized in whorls and lobules, typically exhibiting indistinct cytoplasmic boundaries and round to oval nuclei.[5] Psammoma bodies (see Image. Psammoma Bodies in Meningioma), which are concentric calcified formations, are commonly observed and may account for the radiographic calcifications identified on CT imaging.[31]

While tissue diagnosis is infrequently performed due to the potential for vision loss from biopsy, it can be performed in atypical cases or following surgical decompression. Biopsy usually reveals benign histological characteristics of ONSM.[32] These tumors have low mitotic activity, unremarkable cytology, and a lack of necrosis, corresponding with their slow clinical progression.[6] Atypical or anaplastic variants, although extremely rare at this site, can exhibit increased cellularity, higher mitotic indices, and necrosis. These histological findings indicate more aggressive growth and poorer outcomes.

Immunohistochemistry is essential for diagnosis. ONSMs generally express epithelial membrane antigen and vimentin, aligning with the meningioma phenotype.[33] Progesterone receptor–positive tumors occur frequently and are associated with a more favorable prognosis.[16] The expression of this receptor has prompted interest in the hormonal effects on meningioma biology, especially in orbital and skull-base regions, where there is a notable female predominance. Somatostatin receptor subtype 2 (SSTR2) is a significant immunohistochemical marker in most meningiomas, including ONSMs. An increased concentration of SSTR2 facilitates diagnosis, which can be helpful in certain types of functional imaging and nuclear scintigraphy that specifically detect this marker.[34]

History and Physical

Patients with ONSM typically present with a history of painless, gradual vision deterioration in one eye. The onset is insidious, frequently progressing over months to years, with patients initially observing slight blurring or diminished color perception. Dyschromatopsia is a common initial symptom, as color vision is especially susceptible to optic nerve impairment.[35] In contrast to optic neuritis, pain during extraocular movement is not a characteristic symptom.[36] The lack of pain should prompt consideration of a compressive cause in the relevant clinical context.[37]

Another significant feature is the rate of visual decline. Although the majority of ONSMs progress gradually, some patients may experience rapid deterioration, especially when the tumor invades the optic canal, where spatial constraints exacerbate the compression. Acute and severe vision loss should prompt evaluation for posterior tumor extension or atypical histologic characteristics. Pediatric cases may demonstrate more aggressive behavior, be less frequent, and may be associated with NF2.[38]

Patients can present initially with chronic optic nerve edema due to intraorbital compression of the optic nerve.[39] Eventually, the edema subsides and optic pallor develops. Optociliary shunt vessels can develop in approximately 30% of patients as the optic disc edema resolves.[40] These vessels represent venous collaterals connected to the choroidal circulation, typically forming after chronic central retinal vein obstruction. However, they can also occur in central retinal vein occlusion, optic nerve glioma, and sphenoid wing meningioma. When vision is affected, there is a relative afferent pupillary deficit in the affected eye. Visual field defects can be nonspecific in the affected eye, manifesting as altitudinal defects, generalized constriction, or enlarged blind spots.

On physical examination, diminished visual acuity, and a relative afferent pupillary deficit are common in unilateral disease. Automated perimetry frequently identifies central scotomas or generalized field constriction, which align with the pattern of axonal degeneration. Proptosis may occur in orbital involvement, and optociliary shunt veins may occasionally be observed on the optic disc, indicating collateral venous circulation resulting from persistent compression.[6] Patients may report transient visual loss associated with eye movement, or gaze-evoked amaurosis. 

Fundoscopic findings evolve with disease progression. In the initial phases, the optic disc may appear unremarkable or have slight edema. As the disease progresses, optic atrophy manifests, distinguished by pallor and attenuation of the neuroretinal rim.[35] Optical coherence tomography (OCT) of the retinal nerve fiber layer and ganglion cell complex frequently reveals thinning before the identification of disc pallor.[41] These objective findings are essential for tracking progression and complementing visual field testing. 

The lack of systemic symptoms serves as an additional diagnostic indicator. Patients with ONSM typically lack constitutional symptoms such as fever, malaise, or weight loss, which would indicate inflammatory, infectious, or neoplastic infiltrative conditions. This distinction aids in differentiating ONSM from conditions such as sarcoidosis, lymphoma, or optic perineuritis, which may exhibit greater systemic involvement.[42]

Particular emphasis must be placed on binocular vision and visual field assessments. If the tumor grows posteriorly towards the optic chiasm, the contralateral eye may have mild temporal field loss. This observation is extremely foreboding, indicating a risk of bilateral blindness and warrants immediate imaging and interdisciplinary management. If untreated, this tumor can lead to complete blindness. The classic clinical triad consists of visual loss, optic atrophy, and optociliary shunt vessels, but most patients do not present with all 3 components concurrently.[14][43]

Evaluation

The assessment of ONSM is predominantly dependent on imaging, functional evaluation, and meticulous exclusion of similar conditions. Due to the significant risk of vision loss associated with biopsy, diagnosis is typically established noninvasively. A systematic methodology ensures precise identification and appropriate management.

MRI is the gold standard for diagnosis and has reduced the need for tissue biopsy. The diagnosis of ONSM is confirmed with MRI, especially with gadolinium-enhanced fat-suppression sequences. Thin-slice orbital sequences with fat suppression demonstrate a characteristic tram-track appearance, in which contrast enhancement encircles the nonenhancing optic nerve.[44] Typical appearances of ONSMs on imaging are tubular expansion of the meninges surrounding the optic nerve (62%), globular enlargement (23%), fusiform expansion (11%), and focal enlargement of the optic nerve (4%).[45] In contrast, an optic nerve glioma typically demonstrates homogenous enhancement of the optic nerve and lacks the classic tram track sign. On MRI, ONSMs appear isointense to gray matter on T1-weighted and T2-weighted imaging. Computed tomography (CT) complements MRI by identifying calcifications that strongly support a meningioma diagnosis and assist in distinguishing it from optic neuritis or glioma.[38] CT scans of the orbit and head can delineate the bony anatomy and may reveal hyperostosis, particularly in secondary tumors.

Most meningiomas, including ONSMs, express SSTR2.[34][46] This facilitates the use of 68Ga-DOTATATE or 68Ga-DOTATOC positron emission tomography/computed tomography (PET/CT), demonstrating significant uptake in ONSM and minimal uptake in inflammatory or glial lesions.[47] SSTR-based imaging improves diagnostic specificity, facilitates diagnosis without biopsy, and assists in radiation therapy planning.[48] This modality is useful when MRI findings are ambiguous.

The ophthalmic assessment is essential to determine functional impairment. Automated perimetry measures visual field deficits, which may precede changes in visual acuity.[49] Color vision testing can be altered in patients with ONSM. Funduscopic examination may show signs of optic disc edema and pallor. Optical coherence tomography (OCT) quantifies the thinning of the retinal nerve fiber layer and ganglion cell complex, providing objective indicators of axonal loss that correlate with vision field decline.[50] OCT is especially beneficial for longitudinal monitoring posttreatment because visual acuity alone may not detect minor alterations in vision.[10] Angiography can show reduced perfusion and vascular alterations in patients with optic nerve compression.[41]

Laboratory studies play a limited role but may exclude inflammatory and infiltrative etiologies. Aquaporin-4 and myelin oligodendrocyte glycoprotein antibodies should be tested if demyelinating disease is suspected, but serum angiotensin converting enzyme or IgG4 levels may be beneficial in identifying systemic inflammatory disorders.[51] These tests should be conducted based on clinical suspicion rather than routine investigations. The European Association of Neuro-Oncology recommends MRI for diagnosis, stable disease monitoring, and progression evaluation.[52] Integrating MRI findings with standardized visual evaluations for monitoring is consistent with modern neuro-oncology practices. The assessment of ONSM incorporates high-resolution MRI and CT, functional SSTR imaging, and ophthalmologic evaluations using OCT and perimetry. Biopsy is infrequently required, and laboratory analyses serve as supplementary measures. Timely and accurate diagnosis is essential, as immediate care can stabilize or preserve vision.

Treatment / Management

Observation is the acceptable management strategy when visual function is intact or remains stable, especially in patients who maintain a central visual acuity of 20/50 or better. Neuro-ophthalmologists should closely monitor these cases with a thorough examination, including serial visual field testing and peripapillary retinal nerve fiber layer optical coherence tomography.[50][53] Annual MRI is recommended for surveillance.[4][54]

Tumor resection is almost impossible without incurring a severe vision loss, due to the proximity of the ONSM to the optic nerve. However, surgical resection may be justified in cases of disfiguring proptosis, significant visual decline, or intracranial extension. If the affected eye is blind and the tumor is confined to the orbit, observation is recommended. However, some surgeons advocate surgically resecting the tumor to avoid extension to other areas. If the eye is blind and intracranial extension is present, the tumor and the nerve should be removed. Some authors advocate surgical intervention as a primary treatment, not only to halt disease progression and reduce the risk of future vision loss, but also to reverse visual deficits.[23] Transnasal endoscopic optic nerve decompression has been recently proposed and has shown stabilization, in some cases, improvement in baseline visual function.[55][56]

Conventional radiotherapy has been used both preoperatively and postoperatively.[3][57] More recently, stereotactic radiotherapy has been employed as an alternative to surgery and is now considered the preferred treatment for progressive visual deterioration. Stereotactic radiotherapy has become the modality of choice, as it delivers the appropriate amount of radiation while minimizing exposure to surrounding tissue. However, risks of radiation-induced retinopathy or optic neuropathy are high.[58][59] 

Differential Diagnosis

The differential diagnosis of ONSM encompasses a wide range of neoplastic and nonneoplastic conditions affecting the optic nerve. Because biopsy rarely occurs, meticulous clinical correlation with imaging and functional assessments is crucial to prevent misdiagnosis. The differential diagnosis of ONSM encompasses optic neuritis, perineuritis, optic glioma, lymphoma, metastatic tumors, and systemic inflammatory disorders. Principal distinguishing characteristics are the rate of progression, pain characteristics, response to corticosteroids, imaging patterns, and functional imaging findings. Precise distinction is essential, as therapeutic approaches vary significantly between these entities.

Demyelinating optic neuritis: The predominant mimic is demyelinating optic neuritis.[60] In contrast to ONSM, optic neuritis is generally painful, has an acute or subacute onset, and frequently responds to corticosteroids. Optic neuritis exhibits intraneural enhancement on MRI, while ONSM presents with circumferential sheath enhancement and the classic tram-track sign.[61] Testing for aquaporin-4 and myelin oligodendrocyte glycoprotein antibodies may enhance diagnostic clarity when inflammatory demyelination is suspected.[51]

Optic perineuritis: Another significant consideration is optic perineuritis, an optic nerve sheath inflammatory disorder.[62] Both ONSM and optic perineuritis may exhibit sheath enhancement on MRI. Perineuritis typically manifests with painful visual impairment, is responsive to corticosteroids, and is often associated with systemic autoimmune or viral disorders.[42] The absence of corticosteroid responsiveness and gradual progression suggests a diagnosis of ONSM.

Visual pathway gliomas are the principal neoplastic variant, particularly in children. These tumors originate within the optic nerve and manifest as fusiform enlargements rather than sheath thickening. Histologically, gliomas originate from astrocytes, unlike meningothelial ONSM. Gliomas are commonly associated with neurofibromatosis type 1 (NF1), whereas ONSMs are more commonly associated with NF2 in children.[63]

Optic nerve glioma must also be considered in the differential diagnosis of ONMS because both conditions exhibit progressive visual loss, optic disc changes, and proptosis. Specific characteristics can help in differentiating them.[64] ONSM generally manifests in middle age and is distinguished by a gradual, painless deterioration of vision, often with optic atrophy and optociliary shunt vessels on fundus examination. Conversely, optic nerve gliomas occur predominantly in children, especially among individuals with NF1, and may manifest with rapidly deteriorating vision, strabismus, or nystagmus. Radiological imaging is essential for differentiation.[65]

ONSM demonstrates a characteristic tram-track appearance or doughnut sign on contrast-enhanced MRI, indicating enhancement of the meningioma surrounding the nonenhancing optic nerve. Optic nerve gliomas generally present with fusiform enlargement of the optic nerve with variable enhancement and potential extension into the optic chiasm. Accurate distinction between these entities is crucial, as treatment varies considerably. ONSM is frequently treated with radiotherapy, whereas optic nerve gliomas are typically treated with observation or chemotherapy, particularly when associated with NF1.

Other orbital neoplasms, including lymphoma and metastatic lesions, may similarly resemble ONSM. Orbital lymphoma typically presents with diffuse orbital infiltration characterized by homogenous enhancement, frequently preserving the sheath architecture.[66] Metastatic lesions, although less prevalent, usually have a more aggressive progression and may present with systemic manifestations or a known history of a metastatic tumor.[67] Inflammatory and infiltrative conditions, such as sarcoidosis, idiopathic orbital inflammatory disease (orbital pseudotumor), and immunoglobulin G4-related illness, can affect the optic nerve sheath.[67][68][69]

These diseases generally exhibit systemic symptoms, abnormal laboratory findings, or involvement of additional orbital structures, aiding in their differentiation from isolated ONSM. Furthermore, SSTR positron emission tomography functional imaging has markedly enhanced diagnostic precision.[9] ONSMs exhibit significant uptake attributable to SSTR2 expression, while most inflammatory and glial lesions do not.[69] Integrating with MRI and clinical history reduces the necessity for biopsy and enhances diagnostic certainty.

Surgical Oncology

In the context of ONSM, surgical oncology is approached with considerable caution, as direct surgical manipulation of the optic nerve poses a significant risk of rapid and irreversible blindness due to disruption of the pial blood supply.[70] Surgical intervention is reserved for cases of severe vision loss or blindness, with the primary objectives of minimizing severe, disfiguring proptosis, managing intracranial extension, or relieving persistent pain.[71]

Several surgical methodologies have been developed, encompassing transorbital, orbitocranial, endoscopic, and cranio-orbital approaches, which facilitate partial or subtotal tumor resection and decompression of the optic canal to reduce mass effect.[25] These treatments are primarily palliative rather than curative because total resection is seldom feasible without severe functional repercussions. The principal surgical complications include cerebrospinal fluid leaks, aesthetic abnormalities, cranial neuropathies, and exacerbated orbital dysfunction, limiting the role of surgery in ONSM. Surgical treatment is deemed appropriate solely in exceptional circumstances when the advantages of debulking or decompression surpass the unavoidable risk of postoperative vision impairment and surgical complications.

Radiation Oncology

Radiation therapy has emerged as the primary treatment for ONSM in patients experiencing increasing visual deterioration with retained eyesight, providing a safer and more effective alternative to surgical intervention. Fractionated conformal radiation [4][72] and stereotactic radiotherapy [73][74] are the predominant methodologies, with standard prescriptions delivering standard doses greater than 25 to 30 fractions, optimizing tumor control while safeguarding optic nerve function. Dosimetric objectives [75] emphasize optimizing target coverage while minimizing radiation exposure to adjacent structures, including the contralateral optic nerve, optic chiasm, retina, and brainstem. Results from numerous prospective and retrospective studies have demonstrated stabilization or improvement in visual acuity in most patients, thereby confirming radiation therapy as the standard treatment.[76]

Contemporary methods, such as intensity-modulated radiotherapy,[77] volumetric modulated arc therapy,[78] and proton beam therapy,[79] improve dose conformality and decrease irradiation of healthy tissues, thereby lowering the risk of radiation-induced optic neuropathy, retinopathy, or hypopituitarism. Ongoing clinical trials are investigating adaptive planning, proton therapy, and the integration of advanced imaging techniques to improve treatment precision and functional outcomes. Adverse effects are typically delayed and may include dry eye, radiation-induced cataract, or optic neuropathy. These complications are addressed through diligent follow-up, prompt ophthalmologic assessment, and, when suitable, supportive measures such as corticosteroids or ocular surface therapy.

Prognosis

Life expectancy is excellent because ONSM is typically benign. However, the tumor causes direct compression of the optic nerve, compromising its vascular supply, and in some cases, it infiltrates the optic nerve.[23] The central prognostic factor is visual function. Without treatment, most patients experience progressive, irreversible visual loss from chronic compressive ischemia.

With timely treatment, many patients have stabilization of their vision. Baseline visual acuity, tumor size, and symptom duration before treatment predict functional outcomes. Earlier treatment and better pretreatment vision correlate with an improved prognosis.[11][77] Even after successful control, long-term surveillance is needed to detect delayed treatment-related toxicities (eg, radiation-induced optic neuropathy, cataract, ocular surface complications) that may affect quality of life.[78]

Complications

Complications in ONSM stem from both the disease's natural progression and its therapeutic interventions. Complications include:

• Permanent vision loss and blindness [79]
• Proptosis [80]
• Intracranial injury after surgery [81]
• Cerebrospinal fluid leak [82]
• Extension of the tumor into the optic chiasm [83]
• Radiation-induced optic neuropathy or retinopathy [84]
• Development of cataracts, dry eye, and keratopathy due to radiation therapy [85]

Postoperative and Rehabilitation Care

Treatment for patients with ONSM focuses on systematic neuro-ophthalmic monitoring, ocular surface protection, and prompt intervention to restore vision. Postoperative examination establishes a new visual baseline by using best-corrected visual acuity, color vision testing, pupillary assessment, automated perimetry, and OCT of the peripapillary retinal nerve fiber layer and macular ganglion layers to quantify residual axonal damage and monitor recovery.[86] OCT and perimetry can be used in preoperative and postoperative settings to assist in prognostic counseling.

MRI of the orbits and optic canal is generally performed several months postoperatively to assess the extent of decompression and establish a radiographic baseline, with subsequent periodic monitoring. Timely, symptom-focused management of ocular-surface complications is crucial. Regular application of preservative-free lubrication, eyelid taping, or temporary tarsorrhaphy in cases of lagophthalmos or exposure, and immediate corneal assessment if pain or photophobia arises.[87] Postoperative complications in orbitocranial surgery that require vigilant monitoring include transient or persistent diplopia, ptosis, cranial neuropathies, and cerebrospinal fluid leaks or infection. An interdisciplinary follow-up involving neurosurgery, oculoplastics, and neuro-ophthalmology is advised to optimize patient outcomes.[88]

Consultations

Management of ONSM requires an interdisciplinary clinical approach, including the following healthcare professionals:

• Neurosurgeon
• Neuro-opthalmologist
• Radiation Oncologist
• Neurologist
• Neuroradiologist

Deterrence and Patient Education

Because ONSM is not preventable, efforts focus on early discovery, rapid referral, and patient-focused education. Early diagnosis and treatment can often prevent irreversible blindness. Clinicians should inform patients about warning signs such as painless, progressive vision loss or dyschromatopsia, and patients should seek medical attention promptly. Optic neuritis causes pain, and recovery is possible, but ONSM is painless and progresses rapidly. 

Education also includes high-risk groups. Although the risk for ONSM is unclear, women, especially those on long-term progestin medication, should be aware of the hormonal effects on meningioma proliferation.[18] Ocular signs are more common in children with NF2, necessitating frequent surveillance examinations.[20] Radiotherapy preserves vision but seldom restores it. Discussions must include radiation risks such as cataract formation and dry eye, as well as long-term monitoring.[11] Visual rehabilitation must be part of patient education. Low-vision aids, occupational therapy, and driving restrictions must be addressed immediately if the dominant eye is affected. Advice on adaptable approaches helps patients maintain autonomy and quality of life.

Education should also include patient participation in posttreatment care. Tracking disease progression requires regular ocular examinations, including visual field testing, optical coherence tomography, and MRI. Patient participation with follow-up helps detect vision or tumor changes early, improving care. ONSM deterrence and education should focus on early warning signs, high-risk populations, realistic treatment results, patient rehabilitation, and long-term follow-up. Knowledge enhances outcomes and quality of life for individuals with challenging diagnoses.

Pearls and Other Issues

ONSM is histologically benign yet possibly functionally malignant, with the risk of permanent vision loss. In contrast to many orbital tumors, even small ONSMs can cause significant visual impairment due to their close anatomic proximity to the optic nerve. Signs and symptoms include painless, progressive vision loss, optic atrophy, and optociliary shunt vessels. Warning signs necessitate immediate orbital MRI.

A frequent error is misidentifying ONSM as optic neuritis. Both conditions manifest with unilateral vision loss; however, optic neuritis is characterized by pain, frequently improves spontaneously or with corticosteroids, and predominantly affects younger individuals. Administering corticosteroids without a confirmed diagnosis may delay appropriate treatment, potentially leading to irreparable visual damage.[51]

The timing of therapy presents another concern. When vision is significantly compromised, radiation therapy seldom reinstates function. The goal is to intervene early when visual function is viable because baseline vision is the most significant predictor of outcome. Clinicians should recognize that ONSM may expand into the optic canal and optic chiasm. This posterior spread signifies a critical juncture, as the risk of bilateral sight loss emerges. Identifying early radiographic indicators of optic chiasm involvement is essential for devising radiation fields and advising patients.[78] Preventing errors, such as misdiagnosis and therapeutic delays, can significantly improve patient outcomes.

Enhancing Healthcare Team Outcomes

ONSM requires an interprofessional team management approach. Neuro-ophthalmologists, neuroradiologists, radiation oncologists, neurosurgeons, oculoplastic surgeons, medical physicists, low-vision specialists, optometrists, occupational therapists, and nurses must work together to provide patient-centered care for ONSM. Precision clinical characterization of visual function includes best-corrected acuity, color vision, pupillary responses, automated perimetry, and OCT. Expert imaging interpretation encompasses high-resolution orbital MRI with contrast, thin-section CT of the optic canal, and SSTR imaging in equivocal cases. The neuro-ophthalmologist establishes the functional baseline and tracks change. The neuroradiologist standardizes imaging reports to highlight treatment-planning features. In collaboration with physicists and dosimetrists, the radiation oncologist designs conformal treatment plans that maximize tumor control while minimizing radiation dose to the optic apparatus. The neurosurgeon and oculoplastic surgeon are consulted for selected indications.

Ethical and shared decision-making are essential in managing this condition. Pharmacists and nursing teams provide peritreatment care (ocular-surface protection, corticosteroid tapers when appropriate, pain control, and adherence counseling). Interdisciplinary tumor boards are fundamental in reducing diagnostic delays, treatment errors, and miscommunication. Proactive care coordination includes scheduling surveillance MRI and formal visual testing. Educating patients, defining red-flag symptoms, and ensuring rapid team access maintain safety and long-term quality of life, which can provide better functional outcomes for patients with ONSM.

Review Questions

• Access free multiple choice questions on this topic.
• Click here for a simplified version.
• Comment on this article.

References

1.

Hong S, Usami K, Hirokawa D, Ogiwara H. Pediatric meningiomas: a report of 5 cases and review of literature. Childs Nerv Syst. 2019 Nov;35(11):2219-2225. [PubMed: 31001646]

2.

Shaikh M, Khera P, Yadav T, Garg P. Dural Ectasia of the Optic Nerve: A Rare Presentation in Neurofibromatosis Type I. J Neurosci Rural Pract. 2019 Apr-Jun;10(2):349-351. [PMC free article: PMC6454956] [PubMed: 31001034]

3.

Kheir V, Faouzi M, Borruat FX. Visual Outcomes of Fractionated Radiotherapy in Optic Nerve Sheath Meningioma: A Retrospective Study. Klin Monbl Augenheilkd. 2019 Apr;236(4):526-529. [PubMed: 30812038]

4.

Pandit R, Paris L, Rudich DS, Lesser RL, Kupersmith MJ, Miller NR. Long-term efficacy of fractionated conformal radiotherapy for the management of primary optic nerve sheath meningioma. Br J Ophthalmol. 2019 Oct;103(10):1436-1440. [PubMed: 30573496]

5.

Solli E, Turbin RE. Primary and Secondary Optic Nerve Sheath Meningioma. J Neurol Surg B Skull Base. 2021 Feb;82(1):27-71. [PMC free article: PMC7987404] [PubMed: 33777618]

6.

Vanikieti K, Chaiwithooanukul C, Puataweepong P, Jindahra P, Padungkiatsagul T. Long-Term Visual Function After Fractionated Stereotactic Radiotherapy for Primary Optic Nerve Sheath Meningioma: A Retrospective Analysis of 34 Subjects. Clin Ophthalmol. 2022;16:3119-3128. [PMC free article: PMC9512281] [PubMed: 36172493]

7.

Kanamalla US. The optic nerve tram-track sign. Radiology. 2003 Jun;227(3):718-9. [PubMed: 12773677]

8.

Peyster RG, Hoover ED, Hershey BL, Haskin ME. High-resolution CT of lesions of the optic nerve. AJR Am J Roentgenol. 1983 May;140(5):869-74. [PubMed: 6601426]

9.

Mairot K, Sahakian N, Salgues B, Levy N, Gascon P, Denis D. Somatostatin receptor PET/CT scan as a helpful diagnostic tool for optic nerve sheath meningioma. J Fr Ophtalmol. 2021 Dec;44(10):e619-e621. [PubMed: 34229893]

10.

Tonagel F, Wilhelm H, Kelbsch C, Richter P. Characteristics of peripapillary retinal nerve fiber layer atrophy in glaucoma, optic nerve sheath meningioma, and sphenoid wing meningioma. Graefes Arch Clin Exp Ophthalmol. 2022 Feb;260(2):577-581. [PMC free article: PMC8786747] [PubMed: 34554296]

11.

Tang T, Wang J, Lin T, Zhai Z, Song X. The treatment efficacy of radiotherapy for optic nerve sheath meningioma. Eye (Lond). 2024 Jan;38(1):89-94. [PMC free article: PMC10764342] [PubMed: 37349547]

12.

Hussain ZS, Loya A, Riaz KM, Lee AG. Optic Nerve Sheath Meningiomas: A National Surveillance, Epidemiology, and End Results (SEER) Database Analysis. J Neuroophthalmol. 2024 Sep 01;44(3):360-364. [PubMed: 38127446]

13.

Furdová A, Babál P, Kobzová D. Optic nerve orbital meningioma. Cesk Slov Oftalmol. 2018 Spring;74(1):23-30. [PubMed: 30541293]

14.

Parker RT, Ovens CA, Fraser CL, Samarawickrama C. Optic nerve sheath meningiomas: prevalence, impact, and management strategies. Eye Brain. 2018;10:85-99. [PMC free article: PMC6207092] [PubMed: 30498385]

15.

Hirschmann D, Nasiri D, Entenmann CJ, Haberler C, Roetzer T, Dorfer C, Millesi M. Is location more determining than WHO grade for long-term clinical outcome in patients with meningioma in the first two decades of life? Wien Klin Wochenschr. 2025 Jan;137(1-2):21-30. [PMC free article: PMC11739186] [PubMed: 38819451]

16.

Agopiantz M, Carnot M, Denis C, Martin E, Gauchotte G. Hormone Receptor Expression in Meningiomas: A Systematic Review. Cancers (Basel). 2023 Feb 03;15(3) [PMC free article: PMC9913299] [PubMed: 36765937]

17.

Utsugi R, Okita Y, Kagawa N, Kishima H. Optic nerve sheath meningioma presenting as progressive visual disturbance during pregnancy: A case report. Exp Ther Med. 2023 Jan;25(1):65. [PMC free article: PMC9798152] [PubMed: 36605527]

18.

Roland N, Kolla E, Baricault B, Dayani P, Duranteau L, Froelich S, Zureik M, Weill A. Oral contraceptives with progestogens desogestrel or levonorgestrel and risk of intracranial meningioma: national case-control study. BMJ. 2025 Jun 11;389:e083981. [PMC free article: PMC12153057] [PubMed: 40500141]

19.

Roland N, Froelich S, Weill A. Medroxyprogesterone acetate and meningioma: a global issue. Front Glob Womens Health. 2025;6:1470539. [PMC free article: PMC11979271] [PubMed: 40207201]

20.

Bachir S, Shah S, Shapiro S, Koehler A, Mahammedi A, Samy RN, Zuccarello M, Schorry E, Sengupta S. Neurofibromatosis Type 2 (NF2) and the Implications for Vestibular Schwannoma and Meningioma Pathogenesis. Int J Mol Sci. 2021 Jan 12;22(2) [PMC free article: PMC7828193] [PubMed: 33445724]

21.

Ravnik J, Rowbottom H. The Impact of Molecular and Genetic Analysis on the Treatment of Patients with Atypical Meningiomas. Diagnostics (Basel). 2024 Aug 15;14(16) [PMC free article: PMC11353905] [PubMed: 39202270]

22.

Soni P, Ghufran MS, Olakkaran S, Puttaswamygowda GH, Duddukuri GR, Kanade SR. Epigenetic alterations induced by aflatoxin B₁: An in vitro and in vivo approach with emphasis on enhancer of zeste homologue-2/p21 axis. Sci Total Environ. 2021 Mar 25;762:143175. [PubMed: 33131875]

23.

Rassi MS, Prasad S, Can A, Pravdenkova S, Almefty R, Al-Mefty O. Prognostic factors in the surgical treatment of intracanalicular primary optic nerve sheath meningiomas. J Neurosurg. 2019 Aug 01;131(2):481-488. [PubMed: 30239315]

24.

Narayan D, Rajak S, Patel S, Selva D. Cystic change in primary paediatric optic nerve sheath meningioma. Orbit. 2016 Aug;35(4):236-8. [PubMed: 27310300]

25.

Harini V, Balsamy M. A Rare Case of Optic Nerve Sheath Meningioma in a Pediatric Patient: Diagnosis and Endoscopic Endonasal Surgical Management. J Pharm Bioallied Sci. 2025 Apr-Jun;17(2):97-99. [PMC free article: PMC12373371] [PubMed: 40860008]

26.

Levin LA, Jakobiec FA. Optic nerve tumors of childhood: a decision-analytical approach to their diagnosis. Int Ophthalmol Clin. 1992 Winter;32(1):223-40. [PubMed: 1537660]

27.

Thom M, Martinian L. Progesterone receptors are expressed with higher frequency by optic nerve sheath meningiomas. Clin Neuropathol. 2002 Jan-Feb;21(1):5-8. [PubMed: 11846045]

28.

Lekovic GP, Schwartz MS, Hanna G, Go J. Intra-Orbital Meningioma Causing Loss of Vision in Neurofibromatosis Type 2: Case Series and Management Considerations. Front Surg. 2018;5:60. [PMC free article: PMC6189417] [PubMed: 30356733]

29.

Jacobi DM. Optic nerve sheath meningioma. Clin Exp Optom. 2019 Mar;102(2):188-190. [PubMed: 30054955]

30.

Tan LT, Stewart CM, Sheerin F, MacDonald B, Silva P, Norris JH. Ectopic orbital meningioma: Fact or fiction? Orbit. 2017 Jun;36(3):144-146. [PubMed: 28594302]

31.

Perez GM, Parker JC, Smith JL. Arachnoidal cap cell hyperplasia of the intracanalicular optic nerve sheath. J Clin Neuroophthalmol. 1981 Sep;1(3):173-83. [PubMed: 6286731]

32.

Coombs RA, Chen JJ, Salomão DR, Tajfirouz DA, Eggenberger ER, DiNome MA, Leavitt JA, Pless ML, Garrity JA, Mansukhani SA. Optic Nerve and Optic Nerve Sheath Biopsy Indications and Outcomes. J Neuroophthalmol. 2025 May 15;45(3):267-272. [PubMed: 40369726]

33.

Bhaker P, Tyagi R, Mahajan D, Mohindra S, Vasishta RK. Optic nerve glioma: A great mimicker. Surg Neurol Int. 2014;5:9. [PMC free article: PMC3927089] [PubMed: 24575324]

34.

Ait Sahel O, Hommadi M, Nabih Oueriagli S, Benameur Y, Doudouh A. Optic nerve sheath meningioma detected by somatostatin receptor scintigraphy with [99mTc]Tc-Tektrotyd. Nucl Med Rev Cent East Eur. 2024;27:53-55. [PubMed: 39582302]

35.

Sharanya R, Habeeba C, Kumar K, Shah VM. Clinical and radiological presentation of meningiomas. Indian J Ophthalmol. 2025 May 01;73(5):691-694. [PMC free article: PMC12121868] [PubMed: 40272297]

36.

Sun CB, Jiang B, Liu GH, Xiao Q. [Clinical and imaging characteristics of optic nerve tumors as the differencial diagnosis of optic neuritis]. Zhonghua Yan Ke Za Zhi. 2023 May 11;59(5):367-375. [PubMed: 37151005]

37.

Chaga M, Chen T, Feng W, Pema P, Shah H, Wang T, Conti D, Feng J, Rodrigo MR, Luick E, Thompson D, Baldwin J, Latif B, Hanley J, Danish S. ZAP-X Stereotactic Radiosurgery for Optic Nerve Sheath Meningioma: A Case Report. Cureus. 2025 Jul;17(7):e87094. [PMC free article: PMC12312259] [PubMed: 40747197]

38.

Gupta S, Chattannavar G, Goyal Sharma A, Kekunnaya R. Optic nerve and choroidal calcification in pediatric neurofibromatosis type 2. Am J Ophthalmol Case Rep. 2025 Jun;38:102306. [PMC free article: PMC11997260] [PubMed: 40236506]

39.

Donaldson L, Margolin E. Approach to patient with unilateral optic disc edema and normal visual function. J Neurol Sci. 2021 May 15;424:117414. [PubMed: 33799215]

40.

Manjandavida FP, Honavar SG, Gowrishankar S, Mulay K, Reddy VA, Vemuganti GK. Optic nerve meningeal hemangiopericytoma: a clinicopathologic case report. Surv Ophthalmol. 2013 Jul-Aug;58(4):341-7. [PubMed: 23294915]

41.

Interlandi E, Pellegrini F, Papayannis A, Cuna A, Mandarà E, De Luca M, Cirone D, Ciabattoni C, Marullo M. Optical Coherence Tomography Angiography Findings in Optic Nerve Sheath Meningioma. Case Rep Ophthalmol. 2020 May-Aug;11(2):364-369. [PMC free article: PMC7443631] [PubMed: 32884551]

42.

Kim H, Kim HG, Oh JH, Lee KM. Deep-learning model for diagnostic clue: detecting the dural tail sign for meningiomas on contrast-enhanced T1 weighted images. Quant Imaging Med Surg. 2023 Dec 01;13(12):8132-8143. [PMC free article: PMC10722041] [PubMed: 38106283]

43.

Frisèn L, Royt WF, Tengroth BM. Optociliary veins, disc pallor and visual loss. A triad of signs indicating spheno-orbital meningioma. Acta Ophthalmol (Copenh). 1973;51(2):241-9. [PubMed: 4801582]

44.

Vidal I, Antunes AP, Morgado C, Simas N, Roque R, Albuquerque L. Pearls & Oy-sters: A Challenging Optic Neuropathy-What Not to Miss in Optic Nerve Sheath Enhancement. Neurology. 2024 Jun 11;102(11):e209494. [PubMed: 38759129]

45.

Saeed P, Rootman J, Nugent RA, White VA, Mackenzie IR, Koornneef L. Optic nerve sheath meningiomas. Ophthalmology. 2003 Oct;110(10):2019-30. [PubMed: 14522782]

46.

Nussbaum-Hermassi L, Ahle G, Zaenker C, Duca C, Namer IJ. Optic nerve sheath meningioma detected by single- photon emission computed tomography/computed tomography somatostatin receptor scintigraphy: a case report. J Med Case Rep. 2016 Apr 22;10(1):96. [PMC free article: PMC4841063] [PubMed: 27103315]

47.

Vay SU, Werner JM, Kabbasch C, Schmidt M, Drzezga A, Fink GR, Galldiks N, Warnke C. Uncovering an Optic Nerve Sheath Meningioma Using 68Ga-DOTATATE PET/CT. Clin Nucl Med. 2021 Sep 01;46(9):e464-e465. [PubMed: 33826577]

48.

Yarmohammadi A, Savino PJ, Koo SJ, Lee RR. Case report ⁶⁸Ga-DOTATATE of optic nerve sheath meningioma. Am J Ophthalmol Case Rep. 2021 Jun;22:101048. [PMC free article: PMC7966962] [PubMed: 33748535]

49.

Inoue T, Mimura O, Ikenaga K, Okuno Y, Nishiguchi I. The rapid improvement in visual field defect observed with weekly perimetry during intensity-modulated radiotherapy for optic nerve sheath meningioma. Int Cancer Conf J. 2019 Jul;8(3):136-140. [PMC free article: PMC6545187] [PubMed: 31218191]

50.

Sibony P, Strachovsky M, Honkanen R, Kupersmith MJ. Optical coherence tomography shape analysis of the peripapillary retinal pigment epithelium layer in presumed optic nerve sheath meningiomas. J Neuroophthalmol. 2014 Jun;34(2):130-6. [PubMed: 24625774]

51.

Muro-Fuentes EA, Stunkel L. Diagnostic Error in Neuro-ophthalmology: Avenues to Improve. Curr Neurol Neurosci Rep. 2022 Apr;22(4):243-256. [PMC free article: PMC8940596] [PubMed: 35320466]

52.

Goldbrunner R, Stavrinou P, Jenkinson MD, Sahm F, Mawrin C, Weber DC, Preusser M, Minniti G, Lund-Johansen M, Lefranc F, Houdart E, Sallabanda K, Le Rhun E, Nieuwenhuizen D, Tabatabai G, Soffietti R, Weller M. EANO guideline on the diagnosis and management of meningiomas. Neuro Oncol. 2021 Nov 02;23(11):1821-1834. [PMC free article: PMC8563316] [PubMed: 34181733]

53.

Loo JL, Tian J, Miller NR, Subramanian PS. Use of optical coherence tomography in predicting post-treatment visual outcome in anterior visual pathway meningiomas. Br J Ophthalmol. 2013 Nov;97(11):1455-8. [PubMed: 23966371]

54.

Hénaux PL, Bretonnier M, Le Reste PJ, Morandi X. Modern Management of Meningiomas Compressing the Optic Nerve: A Systematic Review. World Neurosurg. 2018 Oct;118:e677-e686. [PubMed: 30010062]

55.

Maza G, Subramaniam S, Yanez-Siller JC, Otto BA, Prevedello DM, Carrau RL. The Role of Endonasal Endoscopic Optic Nerve Decompression as the Initial Management of Primary Optic Nerve Sheath Meningiomas. J Neurol Surg B Skull Base. 2019 Dec;80(6):568-576. [PMC free article: PMC6864426] [PubMed: 31750042]

56.

Hunt PJ, DeMonte F, Tang RA, Su SY, Raza SM. Surgical Resection of an Optic Nerve Sheath Meningioma: Relevance of Endoscopic Endonasal Approaches to the Optic Canal. J Neurol Surg Rep. 2017 Apr;78(2):e81-e85. [PMC free article: PMC5391263] [PubMed: 28413768]

57.

Sasano H, Shikishima K, Aoki M, Sakai T, Tsutsumi Y, Nakano T. Efficacy of intensity-modulated radiation therapy for optic nerve sheath meningioma. Graefes Arch Clin Exp Ophthalmol. 2019 Oct;257(10):2297-2306. [PubMed: 31377848]

58.

Liu JK, Forman S, Hershewe GL, Moorthy CR, Benzil DL. Optic nerve sheath meningiomas: visual improvement after stereotactic radiotherapy. Neurosurgery. 2002 May;50(5):950-5; discussion 955-7. [PubMed: 11950397]

59.

Ratnayake G, Oh T, Mehta R, Hardy T, Woodford K, Haward R, Ruben JD, Dally MJ. Long-term treatment outcomes of patients with primary optic nerve sheath meningioma treated with stereotactic radiotherapy. J Clin Neurosci. 2019 Oct;68:162-167. [PubMed: 31401001]

60.

Chan F, Fraser C, Brilot F, Dale RC, Ramanathan S. Structural and functional biomarkers of visual dysfunction in MOG antibody-positive optic neuritis: a scoping review. J Neuroimmunol. 2025 Nov 15;408:578715. [PubMed: 40829360]

61.

Johns TT, Citrin CM, Black J, Sherman JL. CT evaluation of perineural orbital lesions: evaluation of the "tram-track" sign. AJNR Am J Neuroradiol. 1984 Sep-Oct;5(5):587-90. [PMC free article: PMC8335125] [PubMed: 6435424]

62.

Madkhali J, Aba Alkhail AB, Aldriweesh MA, Al Malik Y. Bilateral optic perineuritis: a rare manifestation of giant cell arteritis - case report and literature review. Front Ophthalmol (Lausanne). 2025;5:1598302. [PMC free article: PMC12270863] [PubMed: 40687924]

63.

Donthineni PR, Shanbhag SS, Basu S. An Evidence-Based Strategic Approach to Prevention and Treatment of Dry Eye Disease, a Modern Global Epidemic. Healthcare (Basel). 2021 Jan 17;9(1) [PMC free article: PMC7830429] [PubMed: 33477386]

64.

Gorodezki D, Tonagel F, Zipfel J, Mezger M, Haas-Lude K, Holzer U, Nägele T, Schuhmann MU, Ebinger M. MRI-based, three-dimensionally assessed tumor burden and growth velocity to predict visual acuity deterioration in optic pathway glioma - results of a retrospective longitudinal analysis. Childs Nerv Syst. 2025 Jul 11;41(1):230. [PMC free article: PMC12254072] [PubMed: 40643687]

65.

Marjańska A, Styczyńska J, Jatczak-Gaca A, Stachura J, Marjański M, Styczyński J. Predictors in Optic Pathway Gliomas in Neurofibromatosis Type 1: A Single Center Study. Cancers (Basel). 2025 Apr 23;17(9) [PMC free article: PMC12070890] [PubMed: 40361331]

66.

Kim JL, Mendoza PR, Rashid A, Hayek B, Grossniklaus HE. Optic nerve lymphoma: report of two cases and review of the literature. Surv Ophthalmol. 2015 Mar-Apr;60(2):153-65. [PMC free article: PMC4334739] [PubMed: 25595061]

67.

Stephen M, Maruthachalam K, Kasturi N, Periyandavan J. Orbital Metastasis from Hidradenocarcinoma. Rom J Ophthalmol. 2025 Apr-Jun;69(2):287-290. [PMC free article: PMC12277994] [PubMed: 40698115]

68.

Micieli JA, Streutker CJ, McIntyre K. Isolated Optic Perineuritis as the Presenting Sign of Sarcoidosis. J Neuroophthalmol. 2020 Jun;40(2):255-257. [PubMed: 31490345]

69.

Klingenstein A, Haug AR, Miller C, Hintschich C. Ga-68-DOTA-TATE PET/CT for discrimination of tumors of the optic pathway. Orbit. 2015 Feb;34(1):16-22. [PubMed: 25264824]

70.

Turbin RE, Wladis EJ, Frohman LP, Langer PD, Kennerdell JS. Role for surgery as adjuvant therapy in optic nerve sheath meningioma. Ophthalmic Plast Reconstr Surg. 2006 Jul-Aug;22(4):278-82. [PubMed: 16855500]

71.

Turbin RE, Thompson CR, Kennerdell JS, Cockerham KP, Kupersmith MJ. A long-term visual outcome comparison in patients with optic nerve sheath meningioma managed with observation, surgery, radiotherapy, or surgery and radiotherapy. Ophthalmology. 2002 May;109(5):890-9; discussion 899-900. [PubMed: 11986093]

72.

de Melo LP, Arruda Viani G, de Paula JS. Radiotherapy for the treatment of optic nerve sheath meningioma: A systematic review and meta-analysis. Radiother Oncol. 2021 Dec;165:135-141. [PubMed: 34688809]

73.

Ovens C, Dean B, Gzell C, Patanjali N, Jonker B, O'Connor M, Estoesta P, DeMartin T, Fraser C. Optimal management in optic nerve sheath meningioma - A multicentre study and pooled data analysis. J Clin Neurosci. 2020 Oct;80:162-168. [PubMed: 33099341]

74.

Hajikarimloo B, Tos SM, Mohammadzadeh I, Shahabi K, Amjadzadeh M, Golkar Z, Alvani MS, Habibi MA. Stereotactic radiosurgery for optic nerve sheath meningiomas: A comprehensive systematic review and meta-analysis. J Clin Neurosci. 2025 Sep;139:111432. [PubMed: 40580760]

75.

Fariselli L, Marzoli SB, Morlino S, Pinzi V, Pedone C, De Martin E, Romeo A, Tramacere I, Marchetti M. Hypofractionated Radiosurgery (25 Gy/5 Fractions) for Optic Nerve Sheath Meningiomas: Results From an Exploratory Phase 2 Prospective Trial. Int J Radiat Oncol Biol Phys. 2025 Oct 01;123(2):406-414. [PubMed: 40349855]

76.

Koç İ, Yüce Sarı S, Yazıcı G, Kapucu Y, Kıratlı H, Zorlu F. Role of hypofractionated stereotactic radiotherapy for primary optic nerve sheath meningioma. Neurooncol Pract. 2024 Apr;11(2):150-156. [PMC free article: PMC10940822] [PubMed: 38496921]

77.

Tien MC, McDonald HM, Wei E, Micieli JA, Margolin EA. Optic Nerve Sheath Meningiomas: A Retrospective Cohort Study Comparing Outcomes in Treated Versus Observed Patients. J Neuroophthalmol. 2025 Dec 01;45(4):466-472. [PubMed: 39773911]

78.

Deng MY, Rauh S, Anil G, Lischalk JW, Hahnemann L, Eichkorn T, Hörner-Rieber J, Paul A, Sandrini E, Hoegen-Sassmannshausen P, Held T, Regnery S, Bauer L, Sahm F, von Deimling A, Wick A, Wick W, Jungk C, Krieg SM, Herfarth K, Debus J, König L. Analysis of safety and efficacy of proton radiotherapy for optic nerve sheath meningioma. Neurooncol Adv. 2024 Jan-Dec;6(1):vdae160. [PMC free article: PMC11491494] [PubMed: 39434923]

79.

Sharieff JA, Melson A, Algan O. Treatment of Recurrent Optic Nerve Sheath Meningioma With a Secondary Course of Radiotherapy. Cureus. 2021 Sep;13(9):e17935. [PMC free article: PMC8513540] [PubMed: 34660125]

80.

Dolar Bilge A, Yazici B, Güngör AF, Yazici Z. An Atypical Paediatric Optic Nerve Sheath Meningioma. Neuroophthalmology. 2020;44(6):403-406. [PMC free article: PMC7722708] [PubMed: 33335349]

81.

Yamashiro K, Sadato A, Hirose Y. A Patient With Exophytic Primary Optic Nerve Sheath Meningioma: Stratified Risk of Surgery Based on the Morphology. 2023 Jul-Aug 01J Craniofac Surg. 34(5):e495-e497. [PubMed: 37220669]

82.

Hao J, Pircher A, Miller NR, Hsieh J, Remonda L, Killer HE. Cerebrospinal fluid and optic nerve sheath compartment syndrome: A common pathophysiological mechanism in five different cases? Clin Exp Ophthalmol. 2020 Mar;48(2):212-219. [PubMed: 31648390]

83.

Lestak J, Haninec P, Kyncl M, Tintera J. Optic nerve sheath meningioma-findings in the contralateral optic nerve tract: A case report. Mol Clin Oncol. 2020 May;12(5):411-414. [PMC free article: PMC7087475] [PubMed: 32257196]

84.

Gishti O, de Keizer ROB, Detiger SE, van Rij C, Slagter C, Paridaens D. Radiation optic neuropathy and retinopathy in patients with presumed benign intraorbital tumours treated with fractionated stereotactic radiotherapy. Eye (Lond). 2023 Aug;37(12):2470-2474. [PMC free article: PMC10397216] [PubMed: 36513859]

85.

Hamilton SN, Nichol A, Truong P, McKenzie M, Hsu F, Cheung A, Dolman P, Gete E, Ma R. Visual Outcomes and Local Control After Fractionated Stereotactic Radiotherapy for Optic Nerve Sheath Meningioma. Ophthalmic Plast Reconstr Surg. 2018 May/Jun;34(3):217-221. [PubMed: 28422769]

86.

Shin HJ, Costello F. Imaging the optic nerve with optical coherence tomography. Eye (Lond). 2024 Aug;38(12):2365-2379. [PMC free article: PMC11306400] [PubMed: 38961147]

87.

Noorani S, Kim DB. Tape-splint tarsorrhaphy technique to manage exposure keratopathy in a patient refusing surgical intervention. Clin Case Rep. 2023 Aug;11(8):e7797. [PMC free article: PMC10421974] [PubMed: 37575457]

88.

Sulaiman II, Hashim MA, Ismail M. The Complexities of Orbital Arteriovenous Malformations: A Systematic Review of Clinical Features and Treatment Approaches. Cureus. 2024 Oct;16(10):e71323. [PMC free article: PMC11554339] [PubMed: 39529779]

Disclosure: Bhupendra Patel declares no relevant financial relationships with ineligible companies.

Disclosure: Marco Zeppieri declares no relevant financial relationships with ineligible companies.

Disclosure: Edward Margolin declares no relevant financial relationships with ineligible companies.