Superior ophthalmic vein thrombosis (SOVT) is a rare disease in which a thrombus forms in the superior ophthalmic vein (SOV), the main venous drainage pathway of the orbit. It is recognized as a complication that can threaten vision and life and is caused by many underlying diseases.
The superior ophthalmic vein originates at the superomedial angle of the orbital cavity and is formed by the confluence of the angular vein and the supraorbital vein. It drains multiple venous systems, including the central retinal vein and the vortex veins from the choroid, and flows into the cavernous sinus through the superior orbital fissure 1). It is an important structure responsible for most of the orbital venous drainage.
The cavernous sinus is located superior to the sphenoid sinus and lateral to the sella turcica, and the oculomotor, trochlear, abducens, and trigeminal nerves, as well as the internal carotid artery, pass through it. When SOVT progresses to cavernous sinus thrombosis (CST), it can affect these cranial nerves and cause intracranial complications.
The incidence of SOVT is unknown, and it is an extremely rare disease. van der Poel et al. collected a total of only 69 reported cases from the literature between 1975 and 2019, of which 77.8% were aseptic. Sotoudeh et al. (2019) reported an additional 24 cases, of which 50% were septic.
SOVT develops through at least one of the mechanisms of Virchow’s triad (vascular injury, blood stasis, hypercoagulability) and is broadly classified into septic and aseptic types.
QHow rare is superior ophthalmic vein thrombosis?
A
Only 69 cases have been reported in the literature from 1975 to 2019, making it an extremely rare disease. There are no precise data on incidence, and it is diagnosed after differentiating from orbital cellulitis and cavernous sinus thrombosis, which present similar symptoms.
Symptoms of SOVT usually appear unilaterally, but can become bilateral if it progresses to cavernous sinus thrombosis (CST) or is caused by a systemic disease.
Pain: Deep orbital pain is characteristic. It may be accompanied by a feeling of pressure due to orbital congestion.
Eyelid swelling: Caused by congestive edema due to impaired orbital venous drainage.
Visual impairment: Occurs when there is compression of the optic nerve or retinal venous obstruction.
Fever and systemic symptoms: Septic SOVT is accompanied by signs of infection.
In the case reported by Shen (2024) (93-year-old woman), she presented with a 2-week history of left periorbital edema, with left eye visual acuity 20/70 (amblyopic eye) and right eye 20/251). In the pediatric case by Swiatek (2022) (13-year-old boy), redness and swelling of the left eye progressed rapidly within one day, accompanied by signs of sepsis such as fever, tachycardia, and tachypnea2).
Chemosis: A representative finding of congestion due to impaired orbital venous drainage.
Eyelid edema and ptosis: Appear with orbital congestion.
Proptosis: Often painful. In the Swiatek case, it was absent at initial presentation but worsened on day 8 with left eye protrusion2).
Restricted eye movement: In the Shen case, severe restriction of eye movement in all directions was noted, with normal pupillary light reflex and normal intraocular pressure in both eyes1).
Episcleral vascular dilation: Confirmed in the Shen case1).
When cavernous sinus thrombosis develops, symptoms appear in the following order: deep ocular pain, fever, orbital congestion (chemosis, eyelid swelling, ptosis, proptosis), and ocular movement disorders. When caused by sphenoid sinusitis or pharyngitis, abducens nerve palsy is likely to be the initial symptom. In severe cases, venous stasis retinopathy or central retinal vein thrombosis may occur.
Facial/dental infections: Facial cellulitis, masticator space abscess, dental infections.
Others: Mastoiditis, Lemierre syndrome.
Causative bacteria: Staphylococcus aureus and Streptococcus species are the most common.
COVID-19: Cases have been reported in association with infection and vaccination.
In the Swiatek case, sphenoid sinusitis was the cause, with Streptococcus constellatus detected in blood culture and MSSA in sinus culture 2). The Streptococcus milleri group (SMG: S. intermedius, S. constellatus, S. anginosus) is highly involved in sinus lesions, thrives under anaerobic conditions, and tends to form multiple abscesses even during antibiotic therapy 2).
Idiopathic cases without coagulation abnormalities or systemic diseases also exist.
QWhat is the association between COVID-19 and superior ophthalmic vein thrombosis?
A
Cases of SOVT have been reported after COVID-19 infection and COVID-19 vaccination. COVID-19 is known to induce a hypercoagulable state, and its association with venous thrombotic events throughout the body, including the orbit, has attracted attention.
Because the symptoms of SOVT overlap with orbital cellulitis and cavernous sinus thrombosis, imaging is essential. Recommended imaging studies are contrast-enhanced CT (CT angiography) or contrast-enhanced MRI (MR angiography).
Enlargement of the SOV: The outer margin becomes indistinct due to perivascular edema.
Filling defect in the lumen: A non-enhancing area corresponding to the thrombus is characteristic.
Vascular wall enhancement: A thin layered enhancement may be seen between the vessel wall and thrombus.
In the Shen case, CT angiography revealed marked dilation and non-opacification of the left SOV (consistent with acute thrombus), and partial foveal retinal thickening was also suspected 1).
Diffusion-weighted imaging (DWI): Useful as an alternative in patients with contraindications to contrast agents.
In the Swiatek case, contrast-enhanced MRI (T1-weighted with contrast) confirmed thrombosis of the left SOV, with filling defects and lack of enhancement 2).
If infection is unlikely, evaluation for systemic diseases and hypercoagulable disorders should be performed. In the Shen case, workup for systemic disease showed no abnormalities 1).
Comparison of the following imaging findings aids in diagnosis and differential diagnosis.
Both are recommended and are complementary. CT is easily accessible and excellent for evaluating bone lesions. MRI provides detailed soft tissue and cranial nerve evaluation; DWI can be used as an alternative in patients with contraindications to contrast agents.
The optimal treatment for SOVT is not clearly defined, and no large-scale studies or RCTs have been conducted. When the cause is identified, intervention based on the etiology is the principle.
If septic SOVT, orbital cellulitis, or cavernous sinus thrombosis is suspected, empirical treatment with broad-spectrum antibiotics should be initiated immediately. Vancomycin and ceftazidime are commonly used.
In infectious cavernous sinus thrombosis, high-dose intravenous antibiotics should be started immediately, and broad-spectrum antibiotics should be used until culture results are available. Collaboration with otolaryngologists and neurosurgeons may be necessary, and emergency surgical drainage may be required depending on the source of infection.
In the Swiatek case, treatment was initiated with intravenous ceftaroline plus metronidazole, then switched to intravenous ceftriaxone plus oral metronidazole (later changed to intravenous) 2). Since pathogens are often sequestered within the thrombus, some literature recommends continuing antibiotics for at least two weeks after clinical resolution of infection, but consensus on treatment duration has not been established.
When SMG is the cause, abscess control may be difficult with antibiotics alone, and repeated surgical intervention may be necessary 2).
The utility of anticoagulation in isolated SOVT has not been established by RCTs, but it may be considered to prevent thrombus progression to the cavernous sinus or if cavernous sinus thrombosis is already present. The general consensus is that systemic anticoagulation can be initiated if there are no absolute contraindications. In a study by Weerasinghe et al. on cavernous sinus thrombosis, anticoagulation was associated with reduced mortality. The optimal dose and duration have not been established.
In the Swiatek case, therapeutic anticoagulation with enoxaparin was administered, but the risk of abscess formation with hemorrhage in the SOV under anticoagulation was also suggested 2). Warfarin therapy may be used for cerebral venous sinus thrombosis.
Steroids are considered when the condition is non-infectious and consistent with orbital inflammatory syndrome. They may help reduce orbital congestion and proptosis, but there is no integrated evidence.
If orbital abscess or sinus disease is present, drainage of the primary infection source should be performed. Orbital decompression may be considered if optic nerve compression is present, such as in thyroid eye disease. In fulminant cases, successful transarterial thrombectomy has been reported.
In the Shen case, endoscopic sinus surgery with left orbital decompression and sinus drainage was performed, and one month postoperatively, eye movements normalized and other symptoms improved 1).
In the Swiatek case, an orbital abscess formed after bilateral sinus surgery, requiring multiple fronto-orbital incisions for drainage 2).
QIs anticoagulation therapy always necessary?
A
The efficacy of anticoagulation therapy for isolated SOVT has not been established in RCTs. However, from the perspective of preventing thrombus progression to the foveal retinal thickness, the general view is that it can be initiated if there are no absolute contraindications. There are no standardized guidelines for optimal dosage and duration, and decisions must be made on a case-by-case basis.
6. Pathophysiology and Detailed Mechanism of Onset
When the SOV is occluded, venous return from the orbit is impaired, leading to increased intraorbital pressure. This results in proptosis, conjunctival edema, and restricted eye movement. Since the SOV connects directly to the cavernous sinus through the superior orbital fissure, thrombus extension can affect the cranial nerves (III, IV, V1, VI) within the cavernous sinus, causing cavernous sinus syndrome.
In the valveless venous system, infection can easily spread retrograde from the sinuses, face, and orbit to the cavernous sinus, leading to thrombophlebitis and septic emboli, which facilitate the spread of infection 2). As infectious thrombophlebitis progresses, perivenous abscess formation may occur due to the spread of infection around the vein 2).
The SOV drains the choroid via the vortex veins (superior vortex vein → SOV → cavernous sinus, inferior vortex vein → inferior ophthalmic vein → cavernous sinus) 1). When the SOV is occluded, blood flow from the superior venous drainage area is redistributed to the inferior choroidal vessels via collateral pathways. Therefore, choroidal thickening and vascular dilation are more pronounced in the inferotemporal area, which is distant from the occlusion site 1). After recanalization, choroidal thickness and CVI (choroidal vascular index) decrease (by 40.0 μm in the inferotemporal area and 29.9 μm in the superotemporal area) 1).
7. Latest Research and Future Perspectives (Research-stage Reports)
Shen et al. (2024) reported the first longitudinal observation of choroidal changes after SOVT using SS-OCT1). The finding that choroidal thickness and vascular dilation were most pronounced in the direction opposite to the occlusion (inferotemporal area) reflects the remodeling of the vortex vein drainage pathway and may be applicable to understanding venous overload in other choroidal diseases such as central serous chorioretinopathy.
Management of SMG-related orbital abscess (Swiatek 2022)
Swiatek et al. (2022) reported the difficulty of managing cases involving the superior ophthalmic vein thrombosis (SOVT) and bilateral foveal retinal thickness due to sphenoid sinusitis in children, where the SMG was involved 2). Despite treatment with antibiotics and enoxaparin, abscess formation and recurrence occurred, requiring multiple surgeries. Rapid repeat imaging and aggressive surgical intervention when symptoms change are considered effective in reducing long-term sequelae.
Shen M, Iyer PG, Zhou H, et al. Longitudinal SS-OCT choroidal imaging following thrombosis of the superior ophthalmic vein. Am J Ophthalmol Case Rep. 2024;36:102130.
Swiatek K, Peterson E, Gupta L, Timoney P. Pediatric cavernous sinus and superior ophthalmic vein thrombophlebitis complicated by peri-venous orbital abscesses. Am J Ophthalmol Case Rep. 2022;27:101640.
Yi R, Gabbard R, Pratt J, Chang K, Patel RM, Robinson M. Isolated Superior Ophthalmic Vein Thrombosis. Ophthalmic Plast Reconstr Surg. 2024;40(5):e166-e168. PMID: 38771897.
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