Terson syndrome refers to a condition in which intraocular hemorrhage develops after subarachnoid hemorrhage (SAH), subdural hemorrhage, or intracerebral hemorrhage. The intraocular bleeding often takes the form of vitreous hemorrhage or subinternal limiting membrane hemorrhage, and bleeding can also occur around the optic disc and in various retinal layers of the macula (preretinal, intraretinal, subretinal).1)
In 1900, French ophthalmologist Albert Terson first reported vitreous hemorrhage associated with subarachnoid hemorrhage. Since then, intraocular hemorrhage associated with intracranial hemorrhage has been known as Terson syndrome.
The incidence after traumatic brain injury (TBI) has been reported at about 3.1%. It is lower than SAH (19.3%) and intracerebral hemorrhage (9.1%), but the absolute number cannot be ignored because many patients have TBI.1)
In the early stage, it often causes pre-retinal hemorrhage (subinternal limiting membrane hematoma). After that, physical rupture of the internal limiting membrane triggers progression to vitreous hemorrhage. The amount and location of bleeding vary by patient, ranging from mild pre-retinal hemorrhage alone to massive vitreous hemorrhage that prevents a view of the fundus.
No. It is said to occur in 3–20% of subarachnoid hemorrhage cases and in about 20% of acute SAH. Most SAH patients do not develop intraocular bleeding, but it is thought to be more likely when the sudden rise in intracranial pressure is large or when certain anatomical pathways are involved. If vision loss or floaters appear after SAH, prompt ophthalmic evaluation is important.
The main subjective symptom of Terson syndrome is vision loss that appears after intracranial hemorrhage, usually within 2–3 days after the onset of SAH. When the vitreous hemorrhage is large, vision can drop suddenly and severely, and the fundus cannot be seen. Patients may also complain of floaters. Because symptoms of intracranial hemorrhage (severe headache, altered consciousness, nausea) are prominent, eye symptoms are easily overlooked.
It can occur in one eye or both eyes. In SAH patients with impaired consciousness, a complaint of vision loss may not be obtainable, so ophthalmic screening is important.
Initial findings
Sub-internal limiting membrane hematoma (preretinal hemorrhage): Seen around the optic disc and macula in the early stage after onset. The hematoma appears as a dark red, clearly defined elevation.
Small vitreous hemorrhage: The amount of bleeding may still be enough to see the fundus. This is a stage where spontaneous absorption can be expected.
Intraretinal and subretinal hemorrhage: Bleeding may be seen in the layers from around the optic disc to the macula.
Advanced findings
Large vitreous hemorrhage: When the internal limiting membrane breaks down, bleeding into the vitreous cavity increases rapidly, and the fundus can no longer be seen. Vision may fall to only light perception or worse.
Epiretinal membrane: An epiretinal membrane forms as the hemorrhage organizes. This is a complication that greatly affects visual prognosis.
Retinal detachment and proliferative vitreoretinopathy: Prolonged and organized vitreous hemorrhage may form proliferative tissue and progress to tractional retinal detachment. The risk is especially high in younger patients.
Even after vitreous hemorrhage has spontaneously absorbed, follow-up is needed with attention to epiretinal membrane formation. If vision does not improve after spontaneous absorption and OCT shows an epiretinal membrane or macular edema, surgery should be considered.
With mild to moderate vitreous hemorrhage, spontaneous absorption may sometimes be expected. However, absorption can take several weeks to several months, and during that time there is a risk of developing an epiretinal membrane or proliferative vitreoretinopathy. In younger patients in particular, proliferative changes are more likely to occur, so the duration and frequency of follow-up should be carefully considered. In cases of severe vitreous hemorrhage, bilateral involvement, or suspected retinal detachment on B-mode ultrasound, vitrectomy is recommended.
The intracranial hemorrhages that cause Terson syndrome are as follows.
Diagnosis of Terson syndrome is performed as follows.
| Examination method | Main items evaluated | Special notes |
|---|---|---|
| Slit-lamp microscope | Anterior segment and vitreous opacity | Performed under pupil dilation |
| Fundus examination | Preretinal hemorrhage and vitreous hemorrhage | Not possible with severe opacity |
| B-mode ultrasonography | Retinal detachment and proliferative changes | Essential when the fundus cannot be seen. Performed frequently |
| OCT | Sub-internal limiting membrane hemorrhage and epiretinal membrane | Useful when the ocular media are clear |
| Fluorescein fundus angiography | Vascular lesions and ischemic areas | Performed when the ocular media are clear |
When proliferative changes are present, evaluate with the possibility of retinal detachment, subretinal proliferation, and epiretinal membrane in mind. In cases that have passed a long time since onset, or cases that present late because of poor general condition, the risk of proliferative change is higher, so frequent follow-up with B-mode ultrasonography is especially important.
Ophthalmic screening for patients with SAH is strongly recommended to detect and manage Terson syndrome. Even in severe cases with impaired consciousness, fundus examination is possible, and early detection of vitreous hemorrhage can help avoid missing the right time for treatment. In particular, when the fundus cannot be viewed, B-mode ultrasonography is needed to check whether there is retinal detachment. A coordinated system involving neurosurgeons and ophthalmologists is required.
Treatment for Terson syndrome is determined by the severity of vitreous hemorrhage, the pattern of onset (unilateral/bilateral), the patient’s age, the length of time since onset, and the presence of complications. Broadly, there are two options: observation and vitrectomy.
| Condition | Treatment approach |
|---|---|
| Mild to moderate unilateral vitreous hemorrhage (spontaneous absorption can be expected) | Observation (frequent B-scan ultrasound monitoring) |
| Bilateral onset | Actively choose vitrectomy (early improvement in visual function is needed) |
| Young patients | Actively choose vitrectomy (higher risk of proliferative vitreoretinopathy) |
| severe vitreous hemorrhage | vitrectomy (unlikely to resolve on its own) |
| if retinal detachment is suspected on B-scan ultrasound | vitrectomy (leaving it untreated may cause irreversible visual impairment) |
| prolonged hemorrhage cases (including bilateral cases) | vitrectomy |
Even if observation is chosen, perform B-scan ultrasound frequently and watch for retinal detachment and proliferative changes.
Vitrectomy (pars plana vitrectomy: PPV) is performed using a 25G or 27G small-incision system. The main purpose of surgery is to remove the vitreous hemorrhage, which helps restore visual function early and prevent proliferative vitreoretinopathy. Clinical outcomes of vitrectomy for Terson syndrome secondary to TBI are favorable, and early postoperative improvement in vision has been reported in many cases.2,5) Even in pediatric cases, vitrectomy has been reported to yield good anatomic and functional outcomes.6)
The main intraoperative steps are as follows.
Visual prognosis after vitrectomy is greatly affected by whether there is an epiretinal membrane, retinal detachment, or proliferative vitreoretinopathy. If there is only bleeding and no complications, good visual recovery can be expected.
The timing of surgery is decided individually based on the patient’s general condition, amount of bleeding, presence or absence of complications, and age. Bilateral onset, younger age, severe vitreous hemorrhage, and cases in which retinal detachment is suspected on B-mode ultrasound are considered indications for active early surgery. On the other hand, if mild unilateral vitreous hemorrhage is expected to clear on its own, observation can be chosen. However, even during observation, it is essential to monitor for proliferative changes with frequent B-mode ultrasound examinations. Treatment of the SAH itself takes priority, and the timing of eye surgery is decided after the general condition has stabilized, in consultation with neurosurgery.
Several theories have been proposed for the mechanism of Terson syndrome, and the topic is still debated today. The following three theories are the main ones.
A sudden rise in intracranial pressure caused by subarachnoid hemorrhage compresses the central retinal vein within the optic nerve. As a result, central retinal venous pressure rises, and the retinal capillaries and venules rupture, causing vitreous hemorrhage. This theory emphasizes the mechanism in which sudden changes in intracranial pressure are transmitted to the eye’s blood vessels, and it is consistent with findings that the severity of SAH (the degree of intracranial pressure elevation) correlates with the frequency of Terson syndrome.
This theory holds that blood from the subarachnoid hemorrhage that enters the subarachnoid space around the optic nerve flows directly into the eye through an anatomical pathway. The anatomical continuity between the subarachnoid space and the inside of the eyeball forms the basis for onset. This theory can partly explain the pattern in which blood enters beneath the internal limiting membrane.
This theory proposes that there is a cleft around the portion of the central retinal artery and vein that runs within the optic nerve, and that the distal end of this cleft extends to the area around the vessels near the optic disc. Through this route, blood from the subarachnoid space flows beneath the internal limiting membrane to form a subinternal limiting membrane hemorrhage. Later, physical rupture of the internal limiting membrane causes vitreous hemorrhage. This theory well explains the finding of subinternal limiting membrane hemorrhage (preretinal hemorrhage) as an early sign.
Two other theories are also described below.
初期 → 内境界膜下血腫（網膜前出血）の形成 [機序：くも膜下腔の血液が内境界膜下に流入/頭蓋内圧亢進による血管破綻]
↓ 内境界膜の物理的破綻
進行期 → 硝子体腔への出血（硝子体出血） [眼底透見不能・急激な視力低下]
↓ 出血の遷延・器質化
後期 → 黄斑前膜の形成 → 増殖硝子体網膜症 → 牽引性・裂孔原性網膜剝離（特に若年者）At present, no single mechanism has been established, and the mechanism involved may differ from case to case. All of these theories share the idea that sudden intracranial changes caused by SAH trigger intraocular hemorrhage.
In younger patients, the vitreous has not yet undergone enough liquefaction or posterior vitreous detachment, so blood that has leaked into the eye tends to remain in the vitreous and is more likely to promote the formation of fibrovascular membranes through proliferative stimulation. As a result, proliferative vitreoretinopathy (proliferative vitreoretinopathy: PVR) is more likely to develop, and the risk of progression to tractional retinal detachment or rhegmatogenous retinal detachment is higher. It is important to determine how closely to follow the patient by taking both age and the time since onset into account.
The protocol for routine ophthalmic screening in SAH patients (fundus examination and B-mode ultrasonography) varies by facility, and no unified standard has yet been established. Building a system for cooperation between neurosurgery and ophthalmology in deciding when and how to perform ophthalmic screening in severe SAH patients with impaired consciousness is a future challenge.
There are few large comparative studies that have examined whether early intervention (soon after SAH onset) or elective surgery (after confirming spontaneous absorption) is better for visual prognosis and complication rates in Terson syndrome. In particular, more evidence is needed to clarify the benefits of early surgery in bilateral cases and in younger patients.
For cases that show only subinternal limiting membrane hemorrhage without massive vitreous hemorrhage, there are reports of a technique in which Nd:YAG laser is used to create an opening in the internal limiting membrane (a capsulotomy-like approach) to release the hemorrhage into the vitreous cavity. It is attracting attention as a way to rapidly drain the hemorrhage while keeping invasiveness to a minimum, but further verification is needed before it can be established as standard treatment.
Three-dimensional evaluation of hematoma beneath the internal limiting membrane using optical coherence tomography (OCT) and OCT angiography (OCTA), along with prediction of visual prognosis based on it, are being studied. Quantifying the amount of bleeding, layer-by-layer distribution, and structural changes in the fovea may improve the accuracy of decisions about surgical indications.
By developing a standard protocol that defines the timing, methods, and frequency of ophthalmic evaluation after the onset of SAH, Terson syndrome may be detected more reliably and visual outcomes may improve. Building a team-based approach involving emergency care, intensive care, neurosurgery, and ophthalmology is recognized as a future challenge.