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Compressive optic neuropathy (CON) results from intrinsic or extrinsic pressure on the optic nerve, leading to progressive visual dysfunction. Causes include orbital tumors, vascular lesions, inflammatory disease, trauma, and osseous abnormalities, with thyroid-associated orbitopathy and pituitary adenomas representing leading etiologies worldwide. This course reviews the clinical presentation of CON, typically characterized by painless, progressive vision loss, often accompanied by color desaturation, field defects, or changes in the optic disc, as well as the distinguishing features of CON from other optic neuropathies, which can be identified by careful clinical evaluation, detailed imaging, and interdisciplinary collaboration. Untreated disease can progress to irreversible blindness; therefore, timely diagnosis and intervention—whether medical, surgical, or radiotherapeutic—is essential to preserve or restore vision. This course explores the anatomy, pathophysiology, and clinical features of CON, alongside evidence-based strategies for diagnosis and management. Participants will also gain knowledge of key diagnostic tools such as MRI and perimetry, and recognition of red-flag symptoms. This activity for healthcare professionals is designed to enhance the learner's competence in identifying CON, performing the recommended evaluation, and implementing an appropriate interprofessional approach when managing this condition to prevent irreversible optic nerve damage. Objectives: Identify the etiologies of compressive optic neuropathy. Determine the appropriate evaluation of compressive optic neuropathy. Evaluate the management approaches recommended for compressive optic neuropathy. Collaborate with the interprofessional team in the management of compressive optic neuropathy to enhance patient outcomes. Access free multiple choice questions on this topic.

Any intrinsic or extrinsic compression that is present along the optic nerve can produce compressive optic neuropathy (CON). Other than damage by compression, optic nerve damage can occur as a result of demyelination, ischemia, metabolic, and traumatic insults.[1] The most common sign of injury to the nerve is a slow, progressive monocular visual loss often associated with headaches. Bilateral visual loss can result from midline lesions, eg, a pituitary adenoma, craniopharyngioma, meningioma, and giant cerebral aneurysms, or bilateral orbital lesions associated with thyroid disease and sarcoidosis. Correctly identifying the cause of the CON is essential as the underlying etiology guides management, and the wide-ranging differential diagnoses, which have overlapping clinical features, must be excluded. Anatomical Structures of the Optic Nerve The optic nerve contains over 1 million nerve fibers.[2][3] This quantity of fibers demonstrates the complexity and importance that the visual system has had during our evolution. The visual pathway begins in the retina and ends in the visual cortex of the occipital lobe. The retina consists of 2 functional parts: the optic portion and the nonvisual retina. The optic portion of the retina consists of the neural and pigmented layers. In contrast, the nonvisual retina is an extension of the pigmented layer and ends in the ciliary and iridial parts of the retina.[4] The lamina cribrosa of the sclera forms the optic nerve head and exits the orbit through the optic canal. As it leaves the orbit, the optic nerve head is encased by an extension of the cranial dura and the subarachnoid layer, which forms the optic nerve sheath. The axons of the ganglion cells project as the optic nerve and decussate in the optic chiasm before continuing as the optic tract, which courses to the lateral geniculate ganglion and then projects to the primary visual cortex as the optic radiations. The optic nerve averages 50 mm in length and includes a 1 mm intraocular segment, 25 mm intraorbital segment, 9 mm intracanalicular segment, and 16 mm intracranial segment.[5]

The lamina cribrosa of the sclera forms the optic nerve head and exits the orbit through the optic canal. As it leaves the orbit, the optic nerve head is encased by an extension of the cranial dura and the subarachnoid layer, which forms the optic nerve sheath. The axons of the ganglion cells project as the optic nerve and decussate in the optic chiasm before continuing as the optic tract, which courses to the lateral geniculate ganglion and then projects to the primary visual cortex as the optic radiations. The optic nerve averages 50 mm in length and includes a 1 mm intraocular segment, 25 mm intraorbital segment, 9 mm intracanalicular segment, and 16 mm intracranial segment.[5] The optic nerve is a unique white matter tract of the central nervous system (CNS), comprised of over 1 million axons of retinal ganglion cells. Its anatomical course is divided into 4 segments: intraocular, intraorbital, intracanalicular, and intracranial. This trajectory renders the optic nerve susceptible to compressive injuries at multiple levels. In the orbit, lesions (eg, cavernous hemangiomas, optic nerve sheath meningiomas, and gliomas) can exert localized compression. Within the optic canal, the rigid bony confines predispose the nerve to significant functional impairment from even minimal expansion due to trauma, mucocele, or meningioma. Intracranially, lesions at the suprasellar region—including pituitary adenomas, craniopharyngiomas, and tuberculum sellae meningiomas—often compress the optic chiasm or proximal optic nerves, leading to characteristic patterns of visual field loss.[6] Clinical Course of Compressive Optic Neuropathy The natural history of CON varies according to etiology, rate of growth, and the degree of compression. Slow-growing tumors (eg, meningiomas) may initially present with subtle visual deficits, progressive optic atrophy, or slowly enlarging scotomas. In contrast, rapidly expanding lesions, eg, aneurysms or aggressive malignancies, may cause acute or subacute vision loss. In thyroid eye disease, optic neuropathy typically arises in the setting of orbital apex crowding by hypertrophied extraocular muscles, representing a compressive-inflammatory pathophysiology. Left untreated, CON can lead to irreversible optic nerve damage due to chronic ischemia, demyelination, and axonal degeneration.[7]

The natural history of CON varies according to etiology, rate of growth, and the degree of compression. Slow-growing tumors (eg, meningiomas) may initially present with subtle visual deficits, progressive optic atrophy, or slowly enlarging scotomas. In contrast, rapidly expanding lesions, eg, aneurysms or aggressive malignancies, may cause acute or subacute vision loss. In thyroid eye disease, optic neuropathy typically arises in the setting of orbital apex crowding by hypertrophied extraocular muscles, representing a compressive-inflammatory pathophysiology. Left untreated, CON can lead to irreversible optic nerve damage due to chronic ischemia, demyelination, and axonal degeneration.[7] Patterns of spread in CON are closely linked to the anatomical relationships of the optic nerve and visual pathways. Lesions at the orbital apex and optic canal typically produce unilateral vision loss, afferent pupillary defects, and optic disc pallor. Suprasellar masses may affect the optic chiasm, resulting in bitemporal hemianopia due to compression of the crossing nasal fibers. More posteriorly, involvement of the optic tracts can cause incongruous homonymous hemianopic defects. These characteristic field patterns aid localization and underscore the importance of meticulous perimetry in evaluation. Notably, progressive compression often demonstrates a sequence beginning with paracentral scotomas, enlargement of the blind spot, and eventual arcuate or altitudinal defects as axonal loss becomes widespread.[4] From a clinical perspective, CON must be distinguished from other optic neuropathies. While optic neuritis often presents with acute, painful monocular vision loss in young adults, CON typically manifests with insidious, painless, progressive decline in vision. Color desaturation, relative afferent pupillary defect, and optic disc changes are shared features, but the hallmark of CON lies in its association with a compressive lesion, often accompanied by proptosis, motility restriction, or neurological deficits. Neuroimaging, particularly magnetic resonance imaging (MRI) with fat suppression, remains indispensable in delineating the lesion, assessing its relationship to the optic nerve, and planning intervention.[8]

From a clinical perspective, CON must be distinguished from other optic neuropathies. While optic neuritis often presents with acute, painful monocular vision loss in young adults, CON typically manifests with insidious, painless, progressive decline in vision. Color desaturation, relative afferent pupillary defect, and optic disc changes are shared features, but the hallmark of CON lies in its association with a compressive lesion, often accompanied by proptosis, motility restriction, or neurological deficits. Neuroimaging, particularly magnetic resonance imaging (MRI) with fat suppression, remains indispensable in delineating the lesion, assessing its relationship to the optic nerve, and planning intervention.[8] The epidemiology of CON reflects the diversity of underlying etiologies. Orbital tumors are a leading cause in developed nations, whereas infectious and inflammatory lesions, such as tuberculosis, fungal granulomas, and mucormycosis, predominate in resource-limited settings. Thyroid-associated orbitopathy is now recognized as the most common cause of adult orbital disease globally and a significant contributor to compressive neuropathy, especially in populations with high rates of autoimmune thyroid disorders. Pituitary adenomas are the most frequent suprasellar lesions associated with compressive visual loss, with a prevalence estimated at 1 in 1000 individuals. Their indolent growth and predilection for the sellar-suprasellar region underscore the importance of periodic visual assessment in affected patients.[9] The pathophysiology of visual impairment in CON is multifactorial. Primary mechanical compression causes direct disruption of axonal conduction, while secondary ischemia from compromised pial vasculature exacerbates injury. Chronic compression impairs orthograde and retrograde axoplasmic transport, leading to axonal swelling, demyelination, and eventual atrophy. The degree of reversibility depends on the chronicity of compression: acute lesions with preserved axons may recover after decompression, whereas longstanding cases with optic atrophy generally have poor visual prognosis. This dichotomy highlights the critical importance of early diagnosis.[10]

The pathophysiology of visual impairment in CON is multifactorial. Primary mechanical compression causes direct disruption of axonal conduction, while secondary ischemia from compromised pial vasculature exacerbates injury. Chronic compression impairs orthograde and retrograde axoplasmic transport, leading to axonal swelling, demyelination, and eventual atrophy. The degree of reversibility depends on the chronicity of compression: acute lesions with preserved axons may recover after decompression, whereas longstanding cases with optic atrophy generally have poor visual prognosis. This dichotomy highlights the critical importance of early diagnosis.[10] Patterns of spread are particularly important in localizing lesions and predicting outcomes. In the orbital segment, tumors or inflammatory masses tend to displace rather than infiltrate the nerve, producing eccentric compression. Within the optic canal, even small lesions exert disproportionate pressure due to the confined bony space. At the chiasm, midline lesions (eg, pituitary macroadenomas) compress crossing fibers, while lateral lesions (eg, aneurysms or meningiomas) selectively impact ipsilateral fibers. Posteriorly, optic tract lesions may produce homonymous hemianopias with relative sparing of acuity. These predictable patterns form the cornerstone of clinical neuro-ophthalmology.[11] The natural history of untreated CON is generally unfavorable, progressing from subtle deficits to severe, irreversible blindness. However, modern interventions have dramatically altered outcomes. Surgical resection or decompression, radiotherapy, medical management of thyroid eye disease, and targeted therapies for specific tumors have all improved visual prognosis. Nevertheless, treatment outcomes are heavily contingent on early detection. Once optic atrophy is established, visual recovery is minimal. Therefore, a thorough understanding of the disease’s progression and anatomical nuances allows clinicians to identify cases earlier and intervene before irreversible damage ensues.[8]

The natural history of untreated CON is generally unfavorable, progressing from subtle deficits to severe, irreversible blindness. However, modern interventions have dramatically altered outcomes. Surgical resection or decompression, radiotherapy, medical management of thyroid eye disease, and targeted therapies for specific tumors have all improved visual prognosis. Nevertheless, treatment outcomes are heavily contingent on early detection. Once optic atrophy is established, visual recovery is minimal. Therefore, a thorough understanding of the disease’s progression and anatomical nuances allows clinicians to identify cases earlier and intervene before irreversible damage ensues.[8] Therefore, CON is a complex condition that exemplifies the interplay between anatomy, pathophysiology, and clinical presentation. Its natural history, though potentially devastating, offers windows of reversibility when promptly identified and treated. The patterns of spread, dictated by the location and type of compressive lesion, serve as diagnostic beacons in clinical evaluation. As advances in imaging, neurosurgery, orbital surgery, and radiotherapy continue, the outlook for patients with CON is improving. However, success ultimately depends on clinician awareness, timely recognition, and an integrated interprofessional approach. A detailed appreciation of general information, anatomical susceptibility, natural history, and characteristic spread patterns remains indispensable in optimizing care for these patients.[12]

CON arises when the optic nerve or its surrounding structures are subjected to sustained mechanical pressure. This compression can be due to intrinsic lesions of the optic nerve itself or extrinsic processes from adjacent orbital, intracranial, or vascular pathology. Chronic compression disrupts axonal transport, compromises vascular perfusion, and triggers secondary inflammatory cascades, ultimately leading to axonal degeneration, demyelination, and progressive visual loss. Etiologies can be broadly divided into infectious, inflammatory, vascular, traumatic, neoplastic, osseous, and miscellaneous causes, each with distinct clinical and radiological profiles (see Tables 1 and 2). Recognition of the underlying etiology is crucial, as prognosis and therapeutic options vary significantly. Infectious Causes The following infectious causes of granulomatous or mass-like lesions may compress the optic nerve: Fungal infections: Aspergilloma is the most frequently implicated, especially in immunocompromised hosts. Chronic invasive fungal sinusitis can extend into the orbital apex, leading to optic nerve compression.[3][13] Tuberculosis: Orbital or intracranial tuberculomas may rarely exert pressure on the nerve.[14] Clinicians should bear in mind that infectious CON often progresses rapidly and requires urgent antimicrobial and sometimes surgical decompression. Inflammatory Causes Several inflammatory diseases present with orbital or meningeal masses that cause optic nerve compression, including: Idiopathic orbital inflammation (orbital pseudotumor): These etiologies are characterized by diffuse infiltration of orbital tissues, occasionally encasing the optic nerve.[14] Thyroid-associated orbitopathy (Graves’ disease): Extraocular muscle hypertrophy (especially inferior and superior recti) can compress the optic nerve at the orbital apex, one of the most common causes of CON worldwide.[15][16][17] Sarcoidosis: This condition develops due to granulomatous involvement of the orbit, meninges, or optic nerve sheath.[18] IgG4-related disease: Pachymeningitis and orbital pseudotumor are increasingly recognized contributors.[19][20][21][22] Vascular Causes The following vascular malformations and aneurysms may cause a compressive effect: Intracranial aneurysms, particularly those of the internal carotid, anterior communicating, or ophthalmic arteries [23][24]

IgG4-related disease: Pachymeningitis and orbital pseudotumor are increasingly recognized contributors.[19][20][21][22] Vascular Causes The following vascular malformations and aneurysms may cause a compressive effect: Intracranial aneurysms, particularly those of the internal carotid, anterior communicating, or ophthalmic arteries [23][24] Carotid-cavernous fistulas secondary to venous congestion and enlargement of orbital veins, resulting in secondary CON.[25] Venous malformations, varices, and lymphangiomas, producing intermittent compression, often exacerbated by Valsalva maneuvers [26][27] Dolichoectasia or ectatic carotid arteries (may exert mass effect at the optic chiasm or canal) [28][29] Traumatic Causes Traumatic etiologies that may lead to CON include: Orbital fractures with bony displacement impinging on the optic canal [30][31] Subperiosteal hematomas or orbital hematomas following trauma resulting in acute, sight-threatening CON [32][33] Postsurgical scarring or implants (rare) Neoplastic Causes Neoplasms represent the most common category of chronic CON, which usually manifests insidiously, with progressive visual decline and occasionally proptosis. These neoplastic etiologies include: Benign tumors: Meningiomas (optic nerve sheath meningiomas), schwannomas, cavernous hemangiomas, and dermoid cysts [34][35][36][37] Primary malignant tumors: Optic gliomas (especially in NF-1), lymphomas, sarcomas [38][39][40] Secondary tumors: Pituitary adenomas, craniopharyngiomas, and metastases from systemic cancers (breast, lung, prostate) Osseous (Bone-Related) Causes Bony disorders can narrow the optic canal, leading to chronic compression, including: Fibrous dysplasia: Abnormal bone remodeling can narrow the optic canal [41][42] Paget’s disease of bone: Expansile lesions affecting the skull base [43] Osteopetrosis: Thickened, sclerotic bones compressing the optic nerve canal [44][45] Osteomas and hyperostosis: Localized bony overgrowths [46] Langerhans cell histiocytosis: Lesions involving skull base bones [47] Other Causes Mucoceles: Expansion of paranasal sinus mucoceles (commonly ethmoidal or sphenoidal) into the orbital apex [48][49][50][51] Granulomatous meningitis: Tuberculosis or fungal infections, encases the optic nerve [52] Postradiation fibrosis: Late complication of cranial radiotherapy Table 1. Etiologies of Compressive Optic Neuropathy Table Category Examples Table 2. Distinctive Clinical and Imaging Features by Etiology

Mucoceles: Expansion of paranasal sinus mucoceles (commonly ethmoidal or sphenoidal) into the orbital apex [48][49][50][51] Granulomatous meningitis: Tuberculosis or fungal infections, encases the optic nerve [52] Postradiation fibrosis: Late complication of cranial radiotherapy Table 1. Etiologies of Compressive Optic Neuropathy Table Category Examples Table 2. Distinctive Clinical and Imaging Features by Etiology Table Etiology Clinical Features Additionally, the leading causes of CON can vary by region. In Western countries, neoplasms and thyroid-associated orbitopathy represent the most frequent etiologies, while in Asia and Africa, infectious processes such as aspergilloma and tuberculosis occur more commonly. Neoplastic and osseous causes typically produce a slowly progressive course, while trauma, hematomas, and infections more often result in acute or subacute presentations. Patterns of spread can also vary by etiology. Paranasal sinus disease frequently extends into the orbital apex, whereas pituitary and parasellar masses exert pressure on the optic chiasm before involving the optic canal. These distinctions are clinically relevant. Early identification of CON remains essential, as sustained compression leads to irreversible optic atrophy. Furthermore, timely intervention with medical therapy or surgical decompression offers the potential to preserve or restore vision when initiated before permanent damage occurs.

Overall estimates from reported cases of CON are 1.14 to 4 cases per 100,000 individuals per year. Gender, race, ethnicity, and age vary depending on the specific etiology.[53] Due to the numerous etiologies that can cause CON, the estimates of its incidence vary depending on the etiology. Thyroid orbitopathy associated with Graves’ disease occurs with an incidence of 16 cases per 100,000 in females and 2.9 cases per 100,000 in males.[54][55] Craniopharyngioma demonstrates an incidence ranging from 0.5 to 2 cases per 100,000 persons annually.[56] Fibrous dysplasia affects approximately 1 in 5,000 to 10,000 individuals.[57] Orbital hemangiomas account for 8% to 10% of benign tumors in the pediatric population, showing a marked female predominance with a ratio of 5 to 1.[58][59] Pituitary adenomas appear with a frequency of 10.5%, yet these tumors produce visual symptoms only when they enlarge sufficiently to compress the optic nerve or the optic chiasm.[60] Optic gliomas, primarily affecting children, represent 3% to 5% of pediatric tumors.[61] A cerebral aneurysm involving the internal carotid artery near the optic nerve carries a prevalence of 3%.[62][63] CON is not a single disease but a final common pathway caused by a wide spectrum of orbital, intracranial, vascular, infectious, inflammatory, and osseous disorders. As such, the epidemiology of CON reflects the underlying etiologies rather than a unified disease entity. Nonetheless, population-level studies and disease registries provide important insights into its frequency, demographic distribution, and global variation.[53] Global Burden The precise global incidence and prevalence of CON remain undefined due to the diverse etiologies and variable diagnostic practices. Available data suggest that CON accounts for 5% to 15% of all optic neuropathies. In developed regions, neoplasms, eg, meningiomas, pituitary adenomas, and craniopharyngiomas, along with thyroid-associated orbitopathy, represent the leading causes. In low-income and middle-income countries (LMICs), particularly in South Asia and Africa, infectious processes such as invasive fungal sinusitis caused by Aspergillus or Mucor, and granulomatous diseases, including tuberculosis and sarcoidosis, occur more frequently.[64] Age Distribution

The precise global incidence and prevalence of CON remain undefined due to the diverse etiologies and variable diagnostic practices. Available data suggest that CON accounts for 5% to 15% of all optic neuropathies. In developed regions, neoplasms, eg, meningiomas, pituitary adenomas, and craniopharyngiomas, along with thyroid-associated orbitopathy, represent the leading causes. In low-income and middle-income countries (LMICs), particularly in South Asia and Africa, infectious processes such as invasive fungal sinusitis caused by Aspergillus or Mucor, and granulomatous diseases, including tuberculosis and sarcoidosis, occur more frequently.[64] Age Distribution In children, optic pathway gliomas—often linked with neurofibromatosis type 1—constitute the most common cause of CON, while craniopharyngiomas represent another important etiology, especially in late childhood and adolescence. Among young to middle-aged adults, thyroid-associated orbitopathy peaks in the third to fifth decade with a strong female predominance, and pituitary adenomas occur most often between ages 30 and 50. In older adults, meningiomas, particularly optic nerve sheath meningiomas, and metastatic disease appear more commonly after age 50 (see Table 4). Bony disorders, eg, Paget’s disease or osteopetrosis, usually present in middle-to-late adulthood.[65] Sex Distribution Thyroid-associated orbitopathy demonstrates a female-to-male ratio of approximately 5 to 6:1, and optic nerve sheath meningioma shows a ratio of 3 to 4:1. Pituitary adenomas display a slight male predominance in macroadenomas, while microadenomas occur more frequently in women. Trauma-related CON disproportionately affects males, consistent with global injury patterns. Gliomas, sarcoidosis, and infectious causes, eg, invasive aspergillosis, exhibit no significant sex bias (see Table 4).[66] Epidemiology in Various Regions

Thyroid-associated orbitopathy demonstrates a female-to-male ratio of approximately 5 to 6:1, and optic nerve sheath meningioma shows a ratio of 3 to 4:1. Pituitary adenomas display a slight male predominance in macroadenomas, while microadenomas occur more frequently in women. Trauma-related CON disproportionately affects males, consistent with global injury patterns. Gliomas, sarcoidosis, and infectious causes, eg, invasive aspergillosis, exhibit no significant sex bias (see Table 4).[66] Epidemiology in Various Regions Thyroid eye disease affects approximately 16 per 100,000 women and 3 per 100,000 men annually, with complications occurring in about 3% to 8% of cases. Pituitary adenomas account for 10% to 15% of intracranial tumors, and nearly 50% present with visual pathway compression. Meningiomas represent the most common primary intracranial tumor, with an incidence of 8 to 9 per 100,000 annually; optic nerve sheath meningiomas comprise about 2% of orbital tumors. Trauma-related CON, though uncommon, arises in 0.5% to 5% of closed head injuries, particularly when hematomas or fractures cause compression.[67] In India and Southeast Asia, thyroid eye disease remains prevalent but often receives delayed treatment, resulting in higher rates of CON. Invasive fungal sinusitis, particularly aspergillosis and mucormycosis, disproportionately affects diabetic and immunocompromised patients. During the COVID-19 pandemic, thousands of mucormycosis-related CON cases were reported. In Africa, infectious etiologies, eg, tuberculosis and fungal sinusitis, contribute significantly due to higher endemic rates and limited access to specialty care. In Japan and East Asia, thyroid orbitopathy occurs less frequently than in Western populations, while orbital inflammatory disease and IgG4-related disease are more common (see Table 3).[68] Patterns of Spread Paranasal sinus disease, including mucoceles and invasive fungal infections, often extends into the orbital apex and compresses the optic nerve. Sellar and suprasellar tumors, eg, pituitary adenomas and craniopharyngiomas, primarily compress the optic chiasm and retrochiasmal pathways. Lesions of the orbital apex, including inflammation, lymphoma, and sarcoidosis, cause direct optic nerve compression. Bony canal lesions (eg, fibrous dysplasia and osteopetrosis) progressively narrow the optic canal.[69]

Paranasal sinus disease, including mucoceles and invasive fungal infections, often extends into the orbital apex and compresses the optic nerve. Sellar and suprasellar tumors, eg, pituitary adenomas and craniopharyngiomas, primarily compress the optic chiasm and retrochiasmal pathways. Lesions of the orbital apex, including inflammation, lymphoma, and sarcoidosis, cause direct optic nerve compression. Bony canal lesions (eg, fibrous dysplasia and osteopetrosis) progressively narrow the optic canal.[69] Natural History and Prognostic Relevance Slowly progressive etiologies, including meningioma, thyroid eye disease, and fibrous dysplasia, provide a window for recognition and timely intervention. Rapidly progressive causes, including invasive fungal sinusitis, hemorrhage, and metastases, carry a high risk of irreversible blindness unless addressed with urgent treatment. Table Table 3. Major Compressive Optic Neuropathy Etiologies in Different Regions. Table 4. Demographic Patterns of Compressive Optic Neuropathy Etiologies Table Etiology Age Group

The optic nerve is part of the CNS. The mammalian CNS lacks the ability for regeneration and axonal growth. When the optic nerve is exposed to axonal damage, glial scar tissue forms, limiting the diffusion of growth factors.[1] Inhibitory proteins of myelin (eg, Nogo and myelin-associated glycoprotein), low expression of growth factors, and lack of laminin are also some factors that hinder the ability for axonal regrowth.[70] The more proximal the damage of the optic nerve is to the eye, the faster apoptosis of the retinal ganglion cells will occur. Apoptosis will lead to a cascade of events involving p53, which will cause further cell death. A CON can occur by compressing the vascular supply and causing ischemia to the nerve, or by directly causing a mass effect on the axons, thereby impairing axonal transport and signal transmission. The areas most susceptible to compression are located where the nerve passes through small bone structures, eg, the orbital apex and the optic canal. Optic nerve compression, observed in exophthalmos secondary to thyroid disease, results from the enlargement of extraocular muscles due to the proliferation of fibroblasts, increased extracellular matrix, and adipocyte proliferation and differentiation.[15][16] Furthermore, CON develops when mechanical pressure is exerted on the optic nerve or its vascular supply, disrupting its ability to transmit visual information effectively. The optic nerve is uniquely susceptible to compression because it traverses confined anatomical spaces (eg, the orbit, optic canal, and suprasellar cistern), where even small lesions can exert significant mass effect. The pathophysiology involves a combination of mechanical distortion, impaired axoplasmic transport, and vascular compromise.[53] The first insult is often a disruption of axoplasmic flow within retinal ganglion cell axons. Orthograde (from retina to brain) and retrograde (from brain to retina) transport become impaired, leading to congestion, axonal swelling, and eventual stasis, which manifests clinically as visual field defects, particularly central, cecocentral, or junctional scotomas. If compression persists, the nerve fibers experience progressive degeneration.[71]

The first insult is often a disruption of axoplasmic flow within retinal ganglion cell axons. Orthograde (from retina to brain) and retrograde (from brain to retina) transport become impaired, leading to congestion, axonal swelling, and eventual stasis, which manifests clinically as visual field defects, particularly central, cecocentral, or junctional scotomas. If compression persists, the nerve fibers experience progressive degeneration.[71] In parallel, compression may compromise the delicate vascular supply of the optic nerve. The optic nerve is nourished by branches of the ophthalmic artery, the central retinal artery, and the pial circulation. Sustained pressure reduces perfusion, creating zones of ischemia and hypoxia. This vascular insufficiency accelerates axonal injury, leading to functional deficits that may progress even with relatively mild mechanical pressure.[72] Over time, the combined mechanical and ischemic insults lead to loss of retinal ganglion cell axons. Clinically, patients progress from early symptoms, eg, dyschromatopsia, relative afferent pupillary defect (RAPD), and subtle visual field loss, to more advanced features, including severe visual decline and optic disc pallor. Notably, the rate of progression varies with the nature of the compressive lesion; slow-growing meningiomas or pituitary adenomas often allow for partial adaptation, whereas rapidly expanding hematomas or aneurysms may cause abrupt and profound visual compromise. The natural history of CON follows a spectrum: initial axoplasmic stasis leads to vascular compromise, resulting in progressive axonal degeneration and ultimately, optic atrophy. Because axonal loss is irreversible, early recognition and timely decompression are essential to prevent permanent blindness.[4]

Histopathological changes in CON reflect the chronic mechanical stress exerted on the optic nerve fibers, their blood supply, and surrounding connective tissue structures. The primary pathological hallmark is axonal loss due to sustained compression, which leads to secondary degeneration of the retinal ganglion cells. This manifests as thinning of the retinal nerve fiber layer, ultimately progressing to optic atrophy if the underlying cause remains untreated.[73] Microscopically, compressed optic nerves exhibit axonal degeneration and demyelination. Axons within the compressed segment appear attenuated and fragmented, and oligodendrocyte loss is observed, resulting in patchy demyelination. Chronic compression disrupts axoplasmic flow, causing intra-axonal accumulation of organelles and swelling proximal to the lesion. In advanced cases, the nerve parenchyma is replaced by fibrous gliotic tissue, reflecting irreversible scarring.[4] Vascular compromise is a significant contributing factor. Compression of the pial vessels and central retinal artery branches leads to ischemic damage. Histological sections reveal thickened vessel walls, narrowed lumina, and perivascular gliosis, which supports the role of ischemia in disease progression. In some cases, especially with tumors (eg, meningiomas), a dense fibrous reaction in the optic nerve sheath further aggravates compression. The optic disc morphology also correlates with histopathology. Early stages may exhibit disc pallor with preserved cupping, whereas long-standing cases display sectoral or diffuse atrophy. Retrograde degeneration leads to the loss of retinal ganglion cells in the inner retina, which corresponds to the visual field defects observed clinically.[74] Special stains and immunohistochemistry highlight glial proliferation (GFAP-positive astrocytes), loss of axonal markers (eg, neurofilament protein), and deposition of extracellular matrix components in chronic cases. Importantly, unlike glaucomatous optic neuropathy, the predominant mechanisms in CON are mechanical distortion and ischemia, rather than elevated intraocular pressure. Overall, the histopathological spectrum of CON ranges from reversible axonal edema in acute compression to irreversible axonal loss with gliosis in chronic cases, underscoring the importance of early diagnosis and decompression.[12]

Clinical History Patients with CON usually present with chronic progressive vision loss that can be in 1 or both eyes. These patients can present with headaches, nausea, vomiting, diplopia, dyschromatopsia, exophthalmos, an afferent pupillary defect, photophobia, red eye, or unexplained weight loss. Sudden or rapid visual loss is rare except in cases caused by trauma. These cases are usually due to blunt trauma or a penetrating injury. The nerve can be injured at any location along its path, although the orbital apex and the optic canal are the most susceptible areas to damage.[75] Obtaining a comprehensive history helps focus the broad differential diagnosis, including: Symmetric or asymmetric vision loss Slow versus rapid onset of visual loss Family history of cancer History of radiation therapy Cardiovascular risk factors that include hypertension, peripheral vascular disease, and tobacco use Metabolic disease Autoimmune history [76] Patients with CON often present with a subacute or slowly progressive decline in visual function, although the onset may be acute in cases of trauma or vascular compression. A careful and detailed history is crucial for differentiating CON from other optic neuropathies, eg, those with inflammatory, ischemic, or toxic etiologies.[77] Patients typically report a gradually worsening, painless loss of vision in 1 or both eyes. The progression may be asymmetric and is often associated with visual field defects such as central or cecocentral scotomas, altitudinal defects, or peripheral constriction, depending on the site of compression. Color vision loss, especially red desaturation, is an early and sensitive symptom. Diplopia may be reported if the compressive lesion also affects ocular motor nerves or extraocular muscles, as seen in thyroid orbitopathy or orbital tumors. In cases of orbital or parasellar masses, patients may experience proptosis, periocular swelling, or facial numbness. Headache, particularly retro-orbital or periorbital pain, is more common in tumors, aneurysms, or inflammatory lesions, whereas thyroid-associated orbitopathy may present with a history of systemic hyperthyroidism. Traumatic causes are associated with a clear history of orbital or craniofacial injury. A family or personal history of neurofibromatosis, pituitary disease, or systemic malignancy may provide important diagnostic clues.[76] Physical Examination

In cases of orbital or parasellar masses, patients may experience proptosis, periocular swelling, or facial numbness. Headache, particularly retro-orbital or periorbital pain, is more common in tumors, aneurysms, or inflammatory lesions, whereas thyroid-associated orbitopathy may present with a history of systemic hyperthyroidism. Traumatic causes are associated with a clear history of orbital or craniofacial injury. A family or personal history of neurofibromatosis, pituitary disease, or systemic malignancy may provide important diagnostic clues.[76] Physical Examination The hallmark finding in CON is optic nerve dysfunction, characterized by reduced visual acuity, impaired contrast sensitivity, and dyschromatopsia. Pupillary assessment may reveal a RAPD in unilateral or asymmetric cases. Clinical ophthalmic evaluation typically includes: Slit-lamp examination: This test evaluates the retina, retinal arteries and veins, cornea, fovea, optic cup. Tonometry: Intraocular pressure is assessed. Proptosis: Clincal assessment for the presence of unilateral or bilateral protrusion of the eyes.[78] Visual acuity testing: The Snellen chart is used to assess visual acuity at baseline and follow-up assessments; best corrected vision should be recorded. Color vision testing: Ishihara or Farnsworth-Munsell tests (evaluates if a color deficit is present); red desaturation is an early indicator. Pupillary examination: RAPD in asymmetric cases. Visual fields: Visual field testing differentiates central from peripheral visual loss. Automated perimetry (Humphrey 30-2, 24-2) or Goldmann perimetry detects early scotomas, bitemporal defects, and junctional scotomas. Fundus examination: Optic disc edema in acute lesions; temporal pallor or diffuse atrophy in chronic compression. Ocular motility assessment: Testing of extraocular eye movements helps identify restrictions or diplopia associated with orbital lesions.[79]

Visual fields: Visual field testing differentiates central from peripheral visual loss. Automated perimetry (Humphrey 30-2, 24-2) or Goldmann perimetry detects early scotomas, bitemporal defects, and junctional scotomas. Fundus examination: Optic disc edema in acute lesions; temporal pallor or diffuse atrophy in chronic compression. Ocular motility assessment: Testing of extraocular eye movements helps identify restrictions or diplopia associated with orbital lesions.[79] On fundus examination, early cases may show a normal disc (so-called "retrobulbar neuropathy"), while chronic compression often leads to optic disc pallor and atrophy. In some cases, particularly with orbital lesions, optic disc edema may be present initially. Visual field testing reveals defects corresponding to the site of compression, including junctional scotomas in parasellar tumors, bitemporal hemianopia in chiasmal compression from pituitary adenomas, or arcuate/peripheral defects in orbital mass lesions. Proptosis, lid retraction, or restrictive motility defects may be observed in thyroid eye disease and orbital tumors. Cranial nerve involvement, eg, ophthalmoplegia (III, IV, VI), trigeminal sensory loss (V1 distribution), or Horner’s syndrome, suggests a lesion extending into the cavernous sinus or orbital apex. Palpation of the orbit may occasionally reveal firm masses in superficial lesions, while auscultation can detect bruits in carotid–cavernous fistula. Systemic examination findings, including goiter, café-au-lait spots, or lymphadenopathy, may aid in identifying underlying systemic disease.[80] Clinical Relevance A structured history and detailed physical examination not only establish the suspicion of CON but also provide essential localizing information (see Table 6). Identifying associated systemic conditions, the rate of progression, and the presence of red-flag features, eg, rapidly progressive vision loss, severe headache, or neurological deficits, guides urgent imaging and intervention. In India and other low- and middle-income settings, the delayed recognition of subtle early signs often results in advanced disease at presentation, underscoring the importance of meticulous history-taking and comprehensive physical examination in preventing irreversible blindness.[81] Table Table 6. Clinical Findings in Compressive Optic Neuropathy.

The evaluation of CON requires a structured, interprofessional approach combining clinical, laboratory, imaging, and functional tests to confirm the diagnosis, localize the lesion, and guide management (see Image. Compressive Optic Neuropathy Evaluation). The evaluation is guided by international standards while incorporating region-specific protocols.[82] A comprehensive neurological examination, followed by a thorough ophthalmological evaluation, should be performed. The exam will provide a baseline visual acuity and allow the clinician to monitor for progression or improvement. The eye will have reduced visual acuity with CON. The eye can also exhibit a deficiency in color vision, known as dyschromatopsia, which can be evaluated using the Ishihara test plate. Proptosis or resistance to manual pressure suggests the presence of an intraorbital lesion. Ocular motility abnormalities are evaluated by assessing the function and coordination of the eye muscles. The optic disc can be atrophic, edematous, or appear healthy. Optociliary shunt vessels can be identified due to obstruction in the venous return from the orbit.[11] Laboratory Studies Laboratory studies should include complete blood count, comprehensive metabolic panel, lipid panel, thyroid-stimulating hormone (TSH), free thyroxine (T4), triiodothyronine (T3), luteinizing hormone, anti-thyroid antibodies, thyroid-releasing hormone, follicle-stimulating hormone, prolactin, adrenocorticotropic hormone, insulin growth factor-1, cortisol, bone-specific alkaline phosphatase, and prostate-specific antigen. The angiotensin-converting enzyme is usually elevated in more than half of the patients with active sarcoidosis.[83]

Laboratory studies should include complete blood count, comprehensive metabolic panel, lipid panel, thyroid-stimulating hormone (TSH), free thyroxine (T4), triiodothyronine (T3), luteinizing hormone, anti-thyroid antibodies, thyroid-releasing hormone, follicle-stimulating hormone, prolactin, adrenocorticotropic hormone, insulin growth factor-1, cortisol, bone-specific alkaline phosphatase, and prostate-specific antigen. The angiotensin-converting enzyme is usually elevated in more than half of the patients with active sarcoidosis.[83] Inflammatory and autoimmune testing includes erythrocyte sedimentation rate (ESR), C-reactive protein, angiotensin-converting enzyme, antinuclear antibody, antineutrophil cytoplasmic antibody, and IgG4, which assist in diagnosing sarcoidosis, vasculitis, or IgG4–related disease. Endocrine evaluation incorporates thyroid-stimulating hormone, T4, T3, and thyroid-stimulating hormone receptor antibody for Graves orbitopathy, along with a pituitary hormone panel measuring prolactin, growth hormone, adrenocorticotropic hormone, and cortisol. Infectious assessment may involve fungal serology for aspergillosis, tuberculosis polymerase chain reaction, and syphilis screening when indicated. Cerebrospinal fluid analysis becomes necessary when granulomatous or carcinomatous meningitis is suspected.[84] Imaging Studies Imaging studies are the mainstay of CON diagnosis. Brain and orbit magnetic resonance imaging (MRI) scans provide detailed images of the optic nerves, parasellar region, and orbital contents. Therefore, MRI is the preferred modality for diagnostic evaluation. Fat suppression sequences are required to demonstrate enhancing lesions inside the orbit. Thin-slice MRI of the brain and orbits (1–2 mm) with gadolinium enhancement and fat suppression serves as the gold standard for evaluating CON. This modality effectively identifies meningiomas, gliomas, pituitary adenomas, craniopharyngiomas, orbital masses, and aneurysms. Optic nerve sheath meningiomas often display the characteristic “tram-track” or “doughnut” sign.[85]

Imaging studies are the mainstay of CON diagnosis. Brain and orbit magnetic resonance imaging (MRI) scans provide detailed images of the optic nerves, parasellar region, and orbital contents. Therefore, MRI is the preferred modality for diagnostic evaluation. Fat suppression sequences are required to demonstrate enhancing lesions inside the orbit. Thin-slice MRI of the brain and orbits (1–2 mm) with gadolinium enhancement and fat suppression serves as the gold standard for evaluating CON. This modality effectively identifies meningiomas, gliomas, pituitary adenomas, craniopharyngiomas, orbital masses, and aneurysms. Optic nerve sheath meningiomas often display the characteristic “tram-track” or “doughnut” sign.[85] Lesions involving the orbital bones should be examined using a computed tomographic (CT) scan of the head and orbit. CT demonstrates orbital fractures and concomitant injuries in traumatic cases. CT provides superior assessment of bony abnormalities, including fibrous dysplasia, osteoma, fractures, and osteopetrosis. Clinicians frequently employ CT when MRI is contraindicated or as a complementary tool in orbital trauma and the evaluation of calcified lesions.[86] Ultrasonography can be used for intraorbital biopsy of anteriorly located lesions.[87] Angiographic studies are indicated when vascular causes are suspected, including aneurysms, carotid-cavernous fistulas, or ectatic internal carotid arteries. Functional and Electrophysiological Tests Visual evoked potentials (VEP) demonstrating delayed P100 latency or reduced amplitude suggest optic nerve dysfunction. Electroretinography (ERG) helps distinguish between retinal and optic nerve pathology.[88] International and National Guidelines The American Academy of Ophthalmology (AAO) Preferred Practice Patterns in Neuro-ophthalmology (2022) recommend MRI of the brain and orbits as the gold standard, in conjunction with visual field monitoring and endocrine/autoimmune evaluation in select cases. The European Neuro-ophthalmology Society (EUNOS) guidelines emphasize interprofessional collaboration, particularly in pituitary, orbital, and inflammatory disease. The All India Ophthalmological Society (AIOS) neuro-ophthalmology subspecialty group endorses early MRI, systemic evaluation for thyroid- and TB-related causes, and interprofessional tumor board discussions for neoplastic and vascular etiologies.[89]

The American Academy of Ophthalmology (AAO) Preferred Practice Patterns in Neuro-ophthalmology (2022) recommend MRI of the brain and orbits as the gold standard, in conjunction with visual field monitoring and endocrine/autoimmune evaluation in select cases. The European Neuro-ophthalmology Society (EUNOS) guidelines emphasize interprofessional collaboration, particularly in pituitary, orbital, and inflammatory disease. The All India Ophthalmological Society (AIOS) neuro-ophthalmology subspecialty group endorses early MRI, systemic evaluation for thyroid- and TB-related causes, and interprofessional tumor board discussions for neoplastic and vascular etiologies.[89] Differential Diagnosis Exclusion Noncompressive optic neuropathies—including toxic, nutritional, demyelinating, ischemic, and hereditary forms—must be excluded through targeted history, blood testing, and imaging correlation. Comprehensive evaluation of CON integrates clinical examination, visual function testing, MRI or CT imaging, systemic investigations, and electrophysiology. Guidelines consistently highlight MRI with contrast as the diagnostic standard, supplemented by endocrine and autoimmune testing when clinically appropriate. Early detection through this interprofessional approach remains critical for preventing irreversible optic nerve damage.[90]

Compressive Optic Neuropathy Management Approaches The first step in the management of CON is to treat the underlying causative condition. Corticosteroids are beneficial for inflammation associated with CON, eg, in sarcoidosis and thyroid disease. For these conditions, withdrawal of the steroid treatment can cause acute deterioration of vision. Surgical orbital decompression can help to improve CON caused by thyroid ophthalmoplegia.[91][92][93] For tumors intimately attached to the optic nerve (eg, optic nerve meningiomas), surgery can cause further loss of vision. Radiation therapy is beneficial for aggressive recurrent tumors and those located in areas adjacent to cranial nerves and eloquent brain tissue. Radiotherapy can also be used for surgically difficult-to-resect tumors, such as those located in the cavernous sinus. Radiation can rarely cause irreversible optic nerve damage; therefore, this therapy must be used judiciously. In traumatic cases, conservative treatment is appropriate in patients with mild deficits because spontaneous improvement is often possible. Steroids have no benefit for CON caused by trauma. Surgery is used for patients with radiological evidence of CON.[33][94] Direct compression of the optic nerve by bone fragments or a subperiosteal hematoma is usually treated surgically.[94][95] However, surgery carries the risk of complications such as postoperative cerebrospinal fluid leak and meningitis.[96] The management of CON depends on the underlying etiology, the severity of optic nerve compromise, and the patient's overall systemic condition (see Table 7). The primary goal of therapy is to relieve pressure on the optic nerve, preserve visual function, and address the causative pathology. Early diagnosis and intervention are crucial, as prolonged compression often leads to irreversible optic atrophy. Additionally, optimal management of CON requires coordinated care (Please refer to the Consultations section for more information on interprofessional management). Medical Management

The management of CON depends on the underlying etiology, the severity of optic nerve compromise, and the patient's overall systemic condition (see Table 7). The primary goal of therapy is to relieve pressure on the optic nerve, preserve visual function, and address the causative pathology. Early diagnosis and intervention are crucial, as prolonged compression often leads to irreversible optic atrophy. Additionally, optimal management of CON requires coordinated care (Please refer to the Consultations section for more information on interprofessional management). Medical Management High-dose intravenous corticosteroids play a central role in treating inflammatory or infiltrative causes, eg, thyroid eye disease, sarcoidosis, and idiopathic orbital inflammation. These agents reduce edema and mass effect around the optic nerve, often improving vision in the acute phase. For IgG4-related disease, granulomatous disorders, or refractory thyroid orbitopathy, clinicians employ steroid-sparing immunosuppressants and biologic therapies, including rituximab, azathioprine, methotrexate, and mycophenolate mofetil. In infectious cases, eg, aspergilloma or mucormycosis, targeted antifungal therapy must be combined with surgical debridement to achieve disease control. Management of Graves’ orbitopathy may also involve systemic corticosteroids, orbital radiotherapy, and newer biologics (eg, teprotumumab), which have demonstrated efficacy in reducing compressive effects at the orbital apex.[97] Surgical Management

High-dose intravenous corticosteroids play a central role in treating inflammatory or infiltrative causes, eg, thyroid eye disease, sarcoidosis, and idiopathic orbital inflammation. These agents reduce edema and mass effect around the optic nerve, often improving vision in the acute phase. For IgG4-related disease, granulomatous disorders, or refractory thyroid orbitopathy, clinicians employ steroid-sparing immunosuppressants and biologic therapies, including rituximab, azathioprine, methotrexate, and mycophenolate mofetil. In infectious cases, eg, aspergilloma or mucormycosis, targeted antifungal therapy must be combined with surgical debridement to achieve disease control. Management of Graves’ orbitopathy may also involve systemic corticosteroids, orbital radiotherapy, and newer biologics (eg, teprotumumab), which have demonstrated efficacy in reducing compressive effects at the orbital apex.[97] Surgical Management Orbital decompression represents the standard of care in thyroid eye disease complicated by sight-threatening optic neuropathy. Techniques include medial wall, orbital floor, and orbital fat decompression, which can be performed through external or endoscopic approaches. Neoplastic etiologies, including meningioma, glioma, pituitary adenoma, craniopharyngioma, and metastatic tumors, often require surgical resection, with adjuvant radiotherapy in select cases. Functional endoscopic sinus surgery offers effective decompression for patients with mucoceles or paranasal sinus lesions that affect the optic nerve. For vascular lesions (eg, aneurysms), neurosurgical clipping or endovascular interventions—including coiling or stenting—can relieve optic apparatus compression. Traumatic hematomas or fractures occasionally demand urgent surgical repair to prevent irreversible optic nerve injury.[98] Radiotherapy Fractionated stereotactic radiotherapy or Gamma Knife radiosurgery may be considered for unresectable or residual tumors such as meningiomas, craniopharyngiomas, and pituitary adenomas. These techniques stabilize or improve vision in selected patients.[99] Observation and Monitoring

Orbital decompression represents the standard of care in thyroid eye disease complicated by sight-threatening optic neuropathy. Techniques include medial wall, orbital floor, and orbital fat decompression, which can be performed through external or endoscopic approaches. Neoplastic etiologies, including meningioma, glioma, pituitary adenoma, craniopharyngioma, and metastatic tumors, often require surgical resection, with adjuvant radiotherapy in select cases. Functional endoscopic sinus surgery offers effective decompression for patients with mucoceles or paranasal sinus lesions that affect the optic nerve. For vascular lesions (eg, aneurysms), neurosurgical clipping or endovascular interventions—including coiling or stenting—can relieve optic apparatus compression. Traumatic hematomas or fractures occasionally demand urgent surgical repair to prevent irreversible optic nerve injury.[98] Radiotherapy Fractionated stereotactic radiotherapy or Gamma Knife radiosurgery may be considered for unresectable or residual tumors such as meningiomas, craniopharyngiomas, and pituitary adenomas. These techniques stabilize or improve vision in selected patients.[99] Observation and Monitoring Patients with mild compressive lesions and preserved vision may be managed conservatively under close surveillance. Monitoring strategies include serial visual field testing, optical coherence tomography to assess retinal nerve fiber layer thickness, and contrast-enhanced magnetic resonance imaging to detect progression. Any evidence of deteriorating visual function necessitates prompt escalation to medical or surgical intervention.[100] National and International Guidelines

Patients with mild compressive lesions and preserved vision may be managed conservatively under close surveillance. Monitoring strategies include serial visual field testing, optical coherence tomography to assess retinal nerve fiber layer thickness, and contrast-enhanced magnetic resonance imaging to detect progression. Any evidence of deteriorating visual function necessitates prompt escalation to medical or surgical intervention.[100] National and International Guidelines The European Group on Graves’ Orbitopathy (EUGOGO) recommends immediate intravenous methylprednisolone in sight-threatening thyroid eye disease, followed by urgent orbital decompression if no improvement occurs within 1 to 2 weeks. The AAO advocates for an interprofessional approach that involves ophthalmology, neurosurgery, otolaryngology, and radiology. Contrast-enhanced MRI remains the preferred modality, and surgical decompression is advised for progressive vision loss unresponsive to medical therapy. The National Comprehensive Cancer Network (NCCN) emphasizes individualized management of neoplastic causes, with tumor boards often recommending multimodal treatment strategies that combine surgery, radiotherapy, and, when indicated, chemotherapy.[100] Table 7. Etiology-Specific Treatment Approaches Table Etiology First-Line Treatment

Differential diagnoses (see Table 8) that should be considered when evaluating patients with suspected CON include: Glaucoma [101] Ischemic optic neuropathy [102] Retinal vein occlusion Multiple sclerosis Uveitis When evaluating for the specific etiology, the following common disorders should be excluded, as their treatment management differs: Pituitary tumors Schwannoma Meningioma Aneurysm Arteriovenous malformation Lymphoma Sarcomas Metastasis Glioma Trauma Sarcoidosis [103] Table Table 8. Differential Diagnosis of Compressive Optic Neuropathy .

The evidence base for managing CON has significantly expanded in the past 2 decades, with multiple observational studies, retrospective cohorts, and clinical trials evaluating treatment outcomes across infectious, inflammatory, vascular, and neoplastic causes. Much of the evidence stems from outcomes of surgical decompression, radiotherapy, and, more recently, combined multimodal approaches. Surgical Decompression Studies Several large case series and prospective cohorts have documented the role of orbital, optic canal, and intracranial decompression in CON. In thyroid eye disease–related conditions, randomized controlled trials (RCTs), such as the EUGOGO studies, have demonstrated that early decompression significantly improves visual acuity, color vision, and visual fields compared to conservative management. Endoscopic transnasal decompression has also been validated in multiple studies as a minimally invasive approach with reduced morbidity.[53] Radiotherapy Outcomes Radiotherapy has been evaluated extensively in compressive optic neuropathies secondary to meningiomas, lymphoma, and pituitary adenomas. Modern conformal radiotherapy and stereotactic radiosurgery (SRS) techniques, including Gamma Knife and CyberKnife, have shown tumor control rates exceeding 90%, with stabilization or improvement of vision in 60% to 80% of cases. Long-term follow-ups from institutions, eg, the Mayo Clinic and Johns Hopkins, confirm the durability of tumor shrinkage with a relatively low risk of radiation-induced optic neuropathy (RION) when fractionation and dose constraints are respected.[104] Medical Therapy Studies Glucocorticoids remain central for inflammatory causes such as sarcoidosis or idiopathic orbital inflammation. The CIRTED trial (UK, 2018) established the role of intravenous methylprednisolone as first-line treatment in thyroid-associated orbitopathy, showing superior outcomes over oral steroids. More recently, biologics, eg, teprotumumab (an IGF-1R inhibitor), have revolutionized CON management in thyroid orbitopathy, with phase 2 and 3 trials reporting dramatic improvements in proptosis, diplopia, and optic nerve compression relief.[105] Ongoing Trials and Future Directions Several ongoing clinical trials are addressing unresolved questions in CON management, including: Teprotumumab extension studies (OPTIC-X trial): assessing long-term efficacy and relapse rates

Glucocorticoids remain central for inflammatory causes such as sarcoidosis or idiopathic orbital inflammation. The CIRTED trial (UK, 2018) established the role of intravenous methylprednisolone as first-line treatment in thyroid-associated orbitopathy, showing superior outcomes over oral steroids. More recently, biologics, eg, teprotumumab (an IGF-1R inhibitor), have revolutionized CON management in thyroid orbitopathy, with phase 2 and 3 trials reporting dramatic improvements in proptosis, diplopia, and optic nerve compression relief.[105] Ongoing Trials and Future Directions Several ongoing clinical trials are addressing unresolved questions in CON management, including: Teprotumumab extension studies (OPTIC-X trial): assessing long-term efficacy and relapse rates Checkpoint inhibitors and immunotherapies: exploring their role in lymphoma- and sarcoma-related orbital CON Low-dose radiotherapy protocols: aiming to optimize tumor control while minimizing toxicity in meningiomas Advanced neuroimaging biomarkers: investigation of diffusion tensor imaging (DTI) and optical coherence tomography angiography (OCTA) as early predictors of therapeutic response [106] Meta-Analyses and Guidelines Recent meta-analyses (2020–2023) synthesizing outcomes from surgical, radiotherapeutic, and biologic interventions highlight the following: Surgery remains first-line in rapidly progressive CON. Radiotherapy is best suited for benign or malignant tumors with moderate growth rates. Medical therapies (particularly biologics) are transforming management in thyroid-associated cases. International guidelines, including those from the European Society of Endocrinology and North American Neuro-Ophthalmology Society (NANOS), now emphasize individualized, etiology-specific management, supported by robust clinical evidence.[107]

While CON is not universally staged in the same structured way as neoplasms or vascular disease, several frameworks have been proposed to stratify disease severity and guide treatment. These staging systems are primarily based on functional visual outcomes, structural optic nerve damage, and neuroimaging findings, rather than a single uniform pathological criterion. Functional Staging (Vision-Based) CON staging based on function uses the following ophthalmic evaluation findings to stratify disease severity: Stage 0 (preclinical/asymptomatic): Detected incidentally on imaging with no visual field defect, normal visual acuity, and no optic disc changes Stage I (early symptomatic): Mild visual field defect (central or paracentral scotomas, early arcuate defect), normal or slightly reduced visual acuity, subtle color vision loss Stage II (moderate): Significant visual field constriction, RAPD, and reduced contrast sensitivity. Optic disc pallor may begin to appear Stage III (advanced): Severe constriction of fields, marked optic atrophy, and reduced best-corrected visual acuity (<20/200 in severe cases) Stage IV (end-stage): No light perception or minimal residual light perception with complete optic atrophy [118] Radiological Staging (Imaging-Based) The following radiological staging is based on the site and degree of compression determined by MRI/CT evidence: Stage A (proximity): Lesion abutting the optic nerve or chiasm but without deformation Stage B (contact and deformation): Clear contact with optic nerve/chiasm with visible deformation Stage C (signal changes): Optic nerve demonstrates T2 hyperintensity (suggesting edema, ischemia, or demyelination) Stage D (atrophy): Chronic compression with optic nerve thinning and secondary changes in surrounding structures [119] Disease-Specific Staging Some conditions causing CON (eg, thyroid eye disease, optic nerve sheath meningioma) have their own staging systems that overlap with CON, including: Thyroid eye disease: The NOSPECS classification includes optic nerve dysfunction as a late-stage condition. Optic nerve sheath meningioma: Tumor volume and length of encasement on imaging help define progression and therapeutic thresholds.[67] Proposed Composite Clinical-Radiological Staging Several authors have suggested the following integrated staging system: Stage I (radiological): Lesion abutting optic nerve with no functional loss.

Optic nerve sheath meningioma: Tumor volume and length of encasement on imaging help define progression and therapeutic thresholds.[67] Proposed Composite Clinical-Radiological Staging Several authors have suggested the following integrated staging system: Stage I (radiological): Lesion abutting optic nerve with no functional loss. Stage II (subclinical functional loss): Early color vision changes or subtle field defects, preserved acuity. Stage III (established functional loss): Clear field defect, RAPD, disc pallor, and documented compression. Stage IV (irreversible damage): Severe atrophy with profound functional loss, little chance of visual recovery even with decompression.[120] Clinical Relevance of Staging on Management CON does not follow a universally standardized staging system comparable to those used for neoplasms or vascular diseases. However, several frameworks have been developed to help determine disease severity and identify optimal individualized treatment approaches. Generally, in early stages (0–I), management emphasizes observation and close monitoring, with surgical intervention considered if disease progression occurs. Moderate stages (II–III) often require stronger consideration for optic nerve decompression, radiation therapy, or targeted medical therapy, depending on the underlying etiology. End-stage disease (IV) shifts the focus toward preventing contralateral involvement, implementing visual rehabilitation strategies, and providing comprehensive patient counseling to support quality of life.[121]

The prognosis for CON depends on the underlying pathophysiology (vascular insufficiency or axonal damage) present and the duration from the time of presentation to the time of treatment. The recovery of visual symptoms typically correlates with the length of time between presentation and the time to perform the decompression. The consensus in the literature is that the earlier the decompression, the better the ultimate clinical outcome. Complete visual recovery has been seen as early as 1 week.[23] Slow progressive vision improvements have also been reported. More than half of the patients will improve clinically, irrespective of their preoperative visual status.[122] Early decompression is recommended, but good results can still be obtained even if decompression is performed in a delayed manner.[122] Moreover, the prognosis for visual recovery varies significantly depending on the etiology causing the optic nerve compression. For tumor-related etiologies, negative predictive factors for visual improvement are the severity of visual loss, the presence of disc atrophy, recurrent tumor resection, tumor extension to the cavernous sinus, firm tumor consistency, absence of an arachnoid plane around the tumor, extensive tumor resection, and the longer the duration of visual loss. Overall, 60% of patients with tumors will experience some improvement after optic nerve decompression.[123] Factors Influencing Prognosis The prognosis of CON depends on a multitude of factors, including etiology, duration of compression, severity at presentation, and timing of intervention. Unlike other optic neuropathies, CON has a potentially reversible component if diagnosed early and treated promptly, since axonal dysfunction may precede irreversible axonal loss. These factors are associated with the following influences on an individual's prognosis : Etiology: Benign lesions (eg, meningioma, pituitary adenoma) generally carry a better prognosis than malignant or infiltrative causes (eg, lymphoma, metastatic tumors). Duration of compression: Prolonged compression leads to permanent axonal degeneration and optic atrophy. Early intervention before the development of pallor is associated with better visual recovery.

Etiology: Benign lesions (eg, meningioma, pituitary adenoma) generally carry a better prognosis than malignant or infiltrative causes (eg, lymphoma, metastatic tumors). Duration of compression: Prolonged compression leads to permanent axonal degeneration and optic atrophy. Early intervention before the development of pallor is associated with better visual recovery. Severity of visual loss at presentation: Patients presenting with mild to moderate visual loss or subtle field defects are more likely to recover compared to those with profound vision loss or severe optic atrophy. Treatment modality Surgical decompression: Decompression (eg, for pituitary adenoma, tuberculum sellae meningioma) often results in stabilization or improvement of vision, especially if performed early. Medical therapy: Conservative therapies (eg, corticosteroids in inflammatory or infiltrative conditions, radiotherapy for radiosensitive tumors) may also restore function. Timing: Delay in intervention significantly worsens outcomes. Age and general health: Younger patients tend to have better regenerative capacity and visual recovery.[103] Expected Outcomes of Compressive Optic Neuropathy Visual recovery occurs in approximately 60% to 80% of patients following timely decompression, with outcomes closely tied to the preoperative status. Visual field improvement may continue for several months after treatment. Incomplete recovery remains common when patients present with optic atrophy or long-standing compression, as irreversible ganglion cell loss limits visual potential. Recurrence risk persists in cases of residual or recurrent tumors, where repeat compression may develop. Long-term surveillance, including neuroimaging and monitoring of visual function, is essential to detect early signs of recurrence.[122] Long-Term Considerations Permanent visual disability often develops in patients with late presentation, missed diagnosis, or aggressive pathology, and in some cases, vision loss becomes bilateral. Early recognition and timely intervention preserve functional vision, maintaining independence and quality of life. In contrast, delayed treatment frequently results in lifelong visual handicap. Prognostic indicators (see Table 9) further refine expectations into the following: Favorable: Short duration of symptoms, absence of optic disc pallor, and mild to moderate visual field defects.

Permanent visual disability often develops in patients with late presentation, missed diagnosis, or aggressive pathology, and in some cases, vision loss becomes bilateral. Early recognition and timely intervention preserve functional vision, maintaining independence and quality of life. In contrast, delayed treatment frequently results in lifelong visual handicap. Prognostic indicators (see Table 9) further refine expectations into the following: Favorable: Short duration of symptoms, absence of optic disc pallor, and mild to moderate visual field defects. Unfavorable: Severe baseline visual loss, established optic atrophy, older age, and malignant etiology.[124] The prognosis of compressive optic neuropathy ranges from excellent to poor, depending on how early the diagnosis is made and treatment initiated. With prompt decompression or appropriate medical therapy, many patients can achieve significant visual improvement. However, delayed intervention leads to irreversible optic nerve damage, optic atrophy, and permanent visual disability.[125] Table Table 9. Prognostic Indicators in Compressive Optic Neuropathy.

Complications of Compressive Optic Neuropathy CON may lead to complications, eg, papilledema, blurry vision, an afferent pupillary defect, diplopia, nausea, vomiting, permanent vision loss, impaired extraocular motility, and significant limitations in daily activities due to vision impairment.[126] Decompressive surgery, although effective in many cases, carries risks that include hemorrhage, infection, complete vision loss, prolonged intubation, coma, and death. Untreated or late-diagnosed CON can produce a broad spectrum of ocular, neurological, systemic, and treatment-related complications. These complications may arise from the disease itself or from therapeutic interventions (eg, surgery, medical therapy, or radiotherapy).[127] Consequently, early diagnosis and timely intervention remain essential to reduce the risk of these potentially devastating outcomes. Ocular Complications Permanent visual loss frequently develops as progressive and irreversible optic atrophy results from chronic compression, with complete blindness occurring in untreated cases. Visual field defects, including scotomas and hemianopic field loss, may persist or worsen despite decompression. These defects often result in the loss of binocular vision and severe impairment of quality of life. Additionally, optic disc changes, including secondary optic atrophy with marked thinning of the retinal nerve fiber layer, remain common in advanced stages of the disease. Ocular motility disorders result from compression or infiltration of cranial nerves III, IV, or VI, or involvement of the cavernous sinus, producing diplopia and strabismus. Tumors involving the orbit or surgical manipulation may also cause proptosis and lagophthalmos, leading to exposure keratopathy and secondary corneal damage.[128] Neurological Complications Endocrine dysfunction frequently follows pituitary adenomas or their treatment, manifesting as panhypopituitarism, diabetes insipidus, or Cushing’s disease. Moreover, intracranial extension of aggressive or malignant lesions can affect adjacent brain structures, causing seizures, hemiparesis, or altered sensorium. Tumors that obstruct cerebrospinal fluid pathways may lead to hydrocephalus and increased intracranial pressure. Parasellar lesions often compress nearby cranial nerves (III, IV, VI, V1, V2), producing ophthalmoplegia, trigeminal neuropathy, or facial numbness.[129]

Endocrine dysfunction frequently follows pituitary adenomas or their treatment, manifesting as panhypopituitarism, diabetes insipidus, or Cushing’s disease. Moreover, intracranial extension of aggressive or malignant lesions can affect adjacent brain structures, causing seizures, hemiparesis, or altered sensorium. Tumors that obstruct cerebrospinal fluid pathways may lead to hydrocephalus and increased intracranial pressure. Parasellar lesions often compress nearby cranial nerves (III, IV, VI, V1, V2), producing ophthalmoplegia, trigeminal neuropathy, or facial numbness.[129] Treatment-Related Complications Surgical complications include optic nerve injury during decompression, cerebrospinal fluid leakage, meningitis, hemorrhage, and postoperative visual decline due to ischemia or edema. Radiotherapy may cause delayed toxicities, eg, radiation-induced optic neuropathy, retinopathy, dry eye, cataracts, or secondary neoplasia with high cumulative doses. Furthermore, medical therapy also carries risks, including corticosteroids, which may lead to systemic complications, eg, weight gain, hypertension, hyperglycemia, osteoporosis, and immunosuppression, while targeted therapies for thyroid eye disease may produce systemic toxicities, including liver dysfunction and gastrointestinal intolerance.[130] Psychosocial and Functional Complications Vision loss often results in diminished productivity and impaired quality of life, affecting the ability to drive, read, and work. Psychological consequences, eg, anxiety, depression, and social isolation, are common in patients living with chronic visual disability. Many patients require long-term rehabilitation, including low-vision aids, structured follow-up, and coordinated interprofessional care to maintain function and independence.[131]

The management of compressive optic neuropathy requires an interprofessional approach, as the condition often involves not only the optic nerve but also adjacent neurological, endocrine, and orbital structures. Appropriate consultations ensure comprehensive care, optimize visual outcomes, and address systemic and psychosocial aspects, which frequently include the following specialties: Ophthalmology/neuro-ophthalmology Primary consultation for diagnosis, baseline documentation of vision, color vision, contrast sensitivity, and visual fields. Ongoing monitoring of optic disc status (OCT, fundus exam) and visual function post-intervention. Guidance on visual rehabilitation and low vision aids if deficits persist.[39] Neurosurgery Crucial for patients with tumors (pituitary adenomas, meningiomas, craniopharyngiomas) or bony compressive lesions. Surgical planning for optic nerve decompression, tumor resection, or skull base approaches. Postoperative follow-up for complications such as CSF leaks, infections, or neurological deficits.[11] Endocrinology Evaluation of pituitary and hypothalamic function in sellar and parasellar lesions. Hormonal replacement therapy where required (thyroid, adrenal, gonadal, or vasopressin). Long-term monitoring for endocrine dysfunctions after surgery or radiotherapy.[135] Radiation oncology For patients who are not suitable for surgery or have residual/recurrent tumors. Planning and delivery of stereotactic radiosurgery or fractionated radiotherapy. Monitoring for radiation-induced complications (radiation optic neuropathy, retinopathy, cataract).[130] Medical oncology/hematology In cases of malignant, metastatic, or infiltrative lesions (eg, lymphoma, leukaemia, metastasis) Coordination of systemic chemotherapy or targeted therapy [136] Otolaryngology (ENT)/skull base surgery In cases of paranasal sinus tumors, nasopharyngeal masses, or lesions with orbital extension requiring combined surgical approaches [137] Rehabilitation medicine Guidance on visual rehabilitation, mobility training, and occupational adjustments. Prescription of low-vision aids and assistive technology.[138] Psychiatry/psychology Counseling to address depression, anxiety, and adjustment issues secondary to visual disability. Supportive therapy for coping with long-term consequences. Primary care/family physician Coordination of interprofessional care.

Guidance on visual rehabilitation, mobility training, and occupational adjustments. Prescription of low-vision aids and assistive technology.[138] Psychiatry/psychology Counseling to address depression, anxiety, and adjustment issues secondary to visual disability. Supportive therapy for coping with long-term consequences. Primary care/family physician Coordination of interprofessional care. Monitoring systemic comorbidities (eg, diabetes, hypertension) that may worsen prognosis. Ensuring compliance with follow-up schedules and referrals. Consultations for compressive optic neuropathy should always be interprofessional, involving ophthalmology, neurosurgery, endocrinology, and other specialties as dictated by the etiology. This integrated approach ensures not just vision preservation, but also systemic stability, functional rehabilitation, and psychological well-being.[4]

Deterrence and patient education in compressive optic neuropathy depend on early detection, timely referral, and comprehensive patient empowerment. By fostering awareness of warning signs, ensuring consistent long-term follow-up, and facilitating access to rehabilitative and supportive resources, clinicians can significantly lower the risk of irreversible blindness while improving overall quality of life.[139] When vision is significantly affected, the patient should be educated to use safety glasses to protect the unaffected eye. All patients who developed CON should attend their regular ophthalmologist care visits to evaluate for visual improvement or deterioration. As the etiologies of CON are multiple, the patient requires a comprehensive evaluation by an interprofessional team to determine the cause of CON and receive urgent treatment to improve clinical outcomes. Early decompression is recommended for CON, but good results can still be obtained even if decompression is delayed. Patients should see an ophthalmologist as soon as they experience symptoms. More than half of the patients improve irrespective of their pre-operative visual status.[122][123] For tumor-related etiologies, 60% of patients will experience some improvement after optic nerve decompression. Although compressive optic neuropathy often arises from unavoidable structural causes such as tumors or inflammatory lesions, early recognition, preventive strategies, and patient education play a pivotal role in preserving vision and improving long-term outcomes. Effective deterrence focuses on timely diagnosis, risk reduction, adherence to therapy, and empowerment through education. Deterrence Strategies Early detection and proactive screening remain essential in reducing morbidity from CON. Patients with pituitary adenomas, meningiomas, thyroid eye disease, or orbital tumors benefit from regular ophthalmic and neuroimaging evaluations to identify optic nerve compromise at an early stage. Routine visual field testing and OCT facilitate recognition of subtle progression before irreversible vision loss occurs.

Early detection and proactive screening remain essential in reducing morbidity from CON. Patients with pituitary adenomas, meningiomas, thyroid eye disease, or orbital tumors benefit from regular ophthalmic and neuroimaging evaluations to identify optic nerve compromise at an early stage. Routine visual field testing and OCT facilitate recognition of subtle progression before irreversible vision loss occurs. Prompt referral to neurosurgery or oncology when compressive lesions are identified lowers the likelihood of permanent optic atrophy. Optimizing management of systemic conditions, eg, thyroid dysfunction, diabetes, and hypertension, further decreases secondary risks while supporting postoperative recovery. Education of both general practitioners and patients about warning signs, eg,  progressive vision loss, field defects, color desaturation, or proptosis, prevents delayed presentations, promotes earlier specialist referral, and facilitates timely intervention.[140] Patient Education Patient education plays a central role in disease management. Patients must understand that CON represents a potentially reversible cause of vision loss when treated early, but becomes irreversible when neglected. Clinicians should clarify treatment goals with clear discussions of treatment expectations, emphasizing that therapy often aims to stabilize or improve vision rather than guarantee full recovery, particularly in advanced cases. Patients should also be informed about the range of available options, including surgical, medical, and radiation-based therapies, along with their associated risks and benefits. Lifelong surveillance remains essential, requiring periodic ophthalmic assessments and repeat imaging even after successful surgical treatment due to the risk of recurrence or progression. Rehabilitation strategies, including low-vision aids, adaptive technologies, and occupational adjustments, help maintain independence in daily life. Counseling services and family involvement support psychological well-being, promoting effective coping with vision loss.[141] Lifestyle and Preventive Guidance

Lifelong surveillance remains essential, requiring periodic ophthalmic assessments and repeat imaging even after successful surgical treatment due to the risk of recurrence or progression. Rehabilitation strategies, including low-vision aids, adaptive technologies, and occupational adjustments, help maintain independence in daily life. Counseling services and family involvement support psychological well-being, promoting effective coping with vision loss.[141] Lifestyle and Preventive Guidance Preventive measures enhance long-term outcomes by supporting neurological and vascular health. Smoking cessation, regular exercise, a balanced diet, and effective management of metabolic disorders all contribute to improved recovery potential and a reduced disease burden. Patients at higher risk, eg, those with thyroid eye disease, should receive education regarding eye safety and protection to prevent complications such as exposure keratopathy. Adherence to endocrine therapy remains critical in both pituitary and thyroid-related disease.

The most important clinical insight in CON is that visual recovery is time-sensitive—prompt recognition and treatment dramatically alter outcomes. The biggest pitfall is delayed or missed diagnosis due to nonspecific presentations. A structured, interprofessional approach that combines vigilance, timely imaging, and patient education is key to preventing irreversible blindness.[121] Additional key factors clinicians should bear in mind include: Early diagnosis is critical: Visual loss in CON can be reversible if intervention occurs before optic atrophy develops. Subtle clues matter: Progressive visual field defects, especially bitemporal hemianopia, decreased color vision, and relative afferent pupillary defect (RAPD) may precede overt visual loss. Imaging is indispensable: MRI with contrast is the gold standard for detecting compressive lesions; OCT and perimetry provide adjunctive monitoring. Not all visual loss is glaucomatous: Misdiagnosis of CON as glaucoma or optic neuritis is a common pitfall, especially in patients with normal IOP but progressive field defects. Interprofessional care:  Collaboration of care between various specialties (neuro-ophthalmology, neurosurgery, endocrinology, oncology) yields the best long-term outcomes.[142] Disposition Patients with suspected CON require urgent referral for neuroimaging and specialist evaluation. Timely intervention with surgical decompression or medical therapy often preserves vision and prevents permanent deficits. Long-term management extends beyond the acute phase, requiring structured neuro-ophthalmic follow-up, routine imaging surveillance, and comprehensive systemic care, with particular emphasis on endocrine support when pituitary or parasellar disease is involved.[143] Common Pitfalls

Patients with suspected CON require urgent referral for neuroimaging and specialist evaluation. Timely intervention with surgical decompression or medical therapy often preserves vision and prevents permanent deficits. Long-term management extends beyond the acute phase, requiring structured neuro-ophthalmic follow-up, routine imaging surveillance, and comprehensive systemic care, with particular emphasis on endocrine support when pituitary or parasellar disease is involved.[143] Common Pitfalls Several pitfalls frequently complicate the management of CON. Delayed referral remains a major concern, often resulting from misattribution of vision loss to refractive error, cataract, or glaucoma. Exclusive reliance on visual acuity also contributes to underdiagnosis, as many patients retain central vision until late in the disease, while peripheral field loss often goes unnoticed without the use of perimetry. Failure to examine both eyes can lead to missed contralateral involvement, which is common in pituitary and parasellar tumors. Inadequate follow-up after treatment carries a significant risk of missed recurrence or progressive visual decline. Neglecting systemic factors such as hormonal dysfunction or intracranial hypertension may further worsen prognosis and compromise long-term outcomes.[144] Prevention and Long-Term Considerations Preventive strategies and long-term planning strengthen patient outcomes. Education regarding early warning signs—including progressive field loss, color desaturation, diplopia, and proptosis—enhances timely recognition and intervention. Screening protocols for high-risk groups, eg, patients with pituitary adenomas, thyroid eye disease, or orbital tumors, support earlier detection of optic nerve compromise. Regular interprofessional follow-up fosters comprehensive care, reduces the risk of long-term complications, and facilitates timely retreatment when necessary. Integration of vision rehabilitation services should be initiated at an early stage to benefit patients with irreversible deficits by helping preserve independence and quality of life.

CON arises from lesions that mechanically compromise the optic nerve, leading to progressive vision loss if untreated. Causes range from benign tumors such as pituitary adenomas and meningiomas to infiltrative malignancies, orbital disease, and thyroid eye disease. Early recognition and prompt management are essential, as vision may be recoverable in the initial stages but irreversible once optic atrophy develops. Diagnosis requires careful clinical assessment, neuroimaging, and systemic evaluation, while long-term management focuses on surgical, medical, and rehabilitative strategies tailored to the underlying etiology. The management of CON depends on coordinated interprofessional teamwork to optimize diagnostic accuracy, therapeutic outcomes, and patient safety. Ophthalmologists and neuro-ophthalmologists lead in early detection and monitoring, while neurosurgeons perform decompression or tumor resection.[53][145][53] Endocrinologists manage pituitary and hypothalamic dysfunction, and radiation or medical oncologists address residual or malignant disease.[146][147][146] Neuroradiologists play a critical role in determining etiology and monitoring treatment response. Nurses and advanced practitioners reinforce education, perioperative care, and continuity, as well as acting as liaisons between specialists.[148] Pharmacists ensure safe pharmacological therapy and support adherence, providing counseling on potential adverse effects, drug interactions, and adherence strategies, while also supporting cost-effective medication choices and access to specialty therapies.[149][150][151][150][149] Rehabilitation specialists, psychologists, and social workers all contribute to long-term functional recovery, effective coping strategies, and overall quality of life. High-quality outcomes depend on clear communication, shared decision-making, and defined responsibilities among physicians, nurses, pharmacists, and allied health professionals. Regular case conferences and coordinated follow-up prevent delays, misdiagnoses, or treatment complications. By integrating surgical precision, medical expertise, rehabilitative interventions, and psychosocial support, the interprofessional team safeguards vision, enhances safety, and promotes independence for patients living with CON.[152]