Blood can collect behind the eye for a wide range of reasons, from chronic conditions like diabetes and high blood pressure to sudden events like head trauma or a spike in brain pressure. The bleeding can occur in different compartments of the eye, including the vitreous cavity (the gel-filled center), beneath the retina, or within the choroid layer underneath it. Because the eye’s interior blood vessels are tiny and delicate, anything that weakens, inflames, or physically tears them can produce hemorrhage, and the cause matters enormously for treatment and prognosis.
How Blood Ends Up Where It Should Not Be
The retina is one of the most metabolically active tissues in the body, and it depends on a dense network of blood vessels to stay nourished. Those vessels are protected by what researchers call the blood-retinal barrier, a tightly sealed layer of cells that keeps blood components from leaking into surrounding tissue. When the junctions between those cells break down, fluid and blood leak out, producing swelling and hemorrhage that interfere with vision.1PubMed. The blood-retina barrier in health and disease That barrier breakdown is the common thread linking most causes of intraocular bleeding, whether the trigger is a spike in blood sugar, a blow to the face, or a burst aneurysm in the brain.
Blood can pool in several distinct locations. Vitreous hemorrhage means blood has entered the gel that fills most of the eyeball. Subretinal hemorrhage means blood sits between the retina and the pigment layer beneath it. Choroidal hemorrhage means bleeding originates in the vascular layer behind the retina. Each location carries different implications for vision and treatment, but they share a root problem: vessels that have broken or leaked.
Diabetes and Proliferative Retinopathy
Diabetic eye disease is one of the most common reasons blood appears behind the eye. In proliferative diabetic retinopathy, chronically high blood sugar damages the retina’s existing vessels so badly that the body tries to grow new ones. These replacement vessels are fragile, poorly formed, and prone to rupturing. The result is vitreous hemorrhage, sometimes severe enough to block vision entirely.2PubMed Central. Vitreous hemorrhage – Causes, diagnosis, and management
Even after surgery to clear the blood, recurrence is a well-known problem. In a study of nearly 300 eyes that underwent vitrectomy for diabetic vitreous hemorrhage, the most common cause of rebleeding was persistent abnormal blood vessels on the retinal surface, accounting for close to half of recurrences.3PubMed Central. Postvitrectomy diabetic vitreous hemorrhage in proliferative diabetic retinopathy This is why managing blood sugar and getting regular retinal screenings matters so much for people with diabetes. The bleeding is often a late complication, and catching the abnormal vessel growth early gives doctors a chance to intervene with laser treatment or injections before a hemorrhage occurs.
High Blood Pressure and Retinal Vein Occlusions
Chronically elevated blood pressure takes a quiet toll on the eye’s small vessels. Over time, it thickens artery walls, which can compress the veins they cross. When a retinal vein gets pinched off, blood backs up behind the blockage, pressure rises, and the vessel walls eventually give way. This is a retinal vein occlusion, and it causes sudden, painless vision loss along with scattered hemorrhages across the retina.
Population data make the connection between blood pressure and vein occlusions very clear. In the Beaver Dam Eye Study, hypertension was associated with more than five times the odds of branch vein occlusion, and the presence of visible arterial changes in the retina raised the odds even higher.4PubMed Central. The epidemiology of retinal vein occlusion: the Beaver Dam Eye Study A large cohort study looking at different stages of hypertension found that people with stage 2 hypertension had about a third higher risk of retinal vascular occlusion compared to people with normal blood pressure.5PubMed. Retinal Vascular Occlusion Risks in High Blood Pressure and the Benefits of Blood Pressure Control The risk climbs in a dose-dependent way: the higher the pressure, the greater the danger to those tiny retinal veins.
Age-Related Macular Degeneration
Wet age-related macular degeneration is the leading cause of subretinal hemorrhage in older adults. In this condition, abnormal blood vessels grow from the choroid layer up through a thin membrane and into the space beneath the retina.6PubMed Central. Choroidal Neovascularization: Mechanisms of Endothelial Dysfunction These vessels are leaky from the start, and when they rupture, blood spreads beneath the macula, the part of the retina responsible for sharp central vision. The majority of severe vision loss from macular degeneration comes from this “wet” form, where subretinal hemorrhages and scarring destroy the tissue that lets you read, drive, and recognize faces.7PubMed. Wet age-related macular degeneration
The bleeding itself is damaging in two ways. First, the pooled blood physically separates the retina from its nutrient supply. Second, as blood breaks down, its chemical byproducts are toxic to the retinal pigment cells and the photoreceptors sitting above them, leading to cell death that is often irreversible.8PubMed. A systematic review of the cell death mechanisms in retinal pigment epithelium cells and photoreceptors after subretinal hemorrhage – Implications for treatment options This is why wet macular degeneration is treated as urgent: the longer blood sits beneath the retina, the worse the outcome.
Trauma to the Eye or Head
A direct blow to the eye can tear vessels in the choroid, the retina, or both. Blunt trauma from a fist, an elbow, a ball, or even an airbag during a car accident can produce choroidal rupture, where the force cracks the delicate tissue layers beneath the retina. One reported case involved a teenager who developed a crescent-shaped choroidal rupture and subretinal hemorrhage after being struck by an elbow.9PubMed Central. A Case of Expansion of Traumatic Choroidal Rupture with Delayed-Developed Outer Retinal Changes In another case, an airbag impact caused such massive subretinal and vitreous hemorrhage that the patient initially had no light perception in the affected eye.10PubMed Central. Airbag-Associated Severe Blunt Eye Injury Causes Choroidal Rupture and Retinal Hemorrhage: A Case Report
Orbital fractures carry their own bleeding risk. When the bony socket around the eye breaks, blood can accumulate behind the eyeball in what is called a retrobulbar hematoma. If enough blood pools, it compresses the eye and its blood supply, creating an emergency called orbital compartment syndrome that can lead to permanent vision loss if not drained quickly.11PubMed. Diagnosis and management of orbital compartment syndrome caused by retrobulbar hematoma following orbital fractures
Posterior Vitreous Detachment
As you age, the vitreous gel inside your eye gradually shrinks and pulls away from the retina in a process called posterior vitreous detachment. This is extremely common after about age 60 and is usually harmless, producing floaters and brief flashes of light. But the pulling can tug on a retinal blood vessel hard enough to tear it, sending blood into the vitreous cavity. A study tracking eyes with vitreous hemorrhage caused by this detachment found that about 62% of cases cleared on their own over several months, but roughly 17% went on to develop a retinal detachment, mostly within the first three weeks.12PubMed. Vitreous Hemorrhage Due to Posterior Vitreous Detachment: Incidence of Retinal Detachment and Spontaneous Clearance during Observation That early window is why doctors monitor these patients closely even when the bleeding seems minor.
When Brain Bleeds Cause Eye Bleeds
One of the more surprising causes of blood behind the eye has nothing to do with the eye itself. In Terson syndrome, bleeding inside the skull, typically from a ruptured brain aneurysm, drives blood into the eye. The mechanism involves a sudden spike in pressure inside the skull, which gets transmitted along the optic nerve sheath and compresses the central retinal vein.13PubMed. Terson’s syndrome When that vein can no longer drain properly, pressure backs up, the retinal capillaries swell and burst, and hemorrhages appear across the retina and into the vitreous.14PubMed Central. Pathogenesis of Terson syndrome
Terson syndrome matters clinically because the eye findings can be the first visible clue that something catastrophic has happened in the brain. If someone arrives in an emergency room with sudden visual loss and retinal hemorrhages but no obvious eye injury, the possibility of a subarachnoid hemorrhage needs to be on the table.
Straining, Coughing, and Valsalva Retinopathy
Heavy straining, forceful vomiting, intense coughing fits, or even heavy weightlifting can cause a sudden rise in pressure inside the chest, which gets transmitted to the veins draining the eye. In rare cases, this spike is enough to rupture the tiny capillaries around the macula, producing a collection of blood right in front of the central retina. This is called Valsalva retinopathy, and it tends to strike otherwise young, healthy people who are blindsided by sudden blurry or blocked central vision after an episode of heavy exertion.15PubMed Central. Valsalva Retinopathy in a Young Patient: A Case Report The good news is that it usually resolves on its own over weeks as the blood reabsorbs, though larger hemorrhages sometimes require laser treatment to drain the trapped blood.
Medications That Increase Bleeding Risk
Blood thinners are a well-recognized risk factor. A review of global safety data identified hundreds of reports of intraocular hemorrhage linked to both traditional and newer anticoagulants. Warfarin showed the strongest association with choroidal hemorrhage, while newer agents like rivaroxaban and dabigatran were more strongly associated with retinal and vitreous hemorrhage.16PubMed Central. Risk of intraocular hemorrhage with new oral anticoagulants This does not mean these medications cause hemorrhage out of the blue. Rather, if someone already has fragile retinal vessels from diabetes, macular degeneration, or vein disease, anticoagulants make it easier for those vessels to bleed and harder for the bleeding to stop.
Repeated eye injections, which are now standard treatment for wet macular degeneration and diabetic eye disease, carry a small bleeding risk of their own. The needle can nick a retinal or ciliary vessel, and patients whose eyes still harbor abnormal, fragile vessels may be particularly susceptible to post-injection vitreous hemorrhage.17American Journal of Ophthalmology. Intravitreal injection history and cataract surgery complications: A multicenter retrospective cohort
Autoimmune and Infectious Inflammation
The eye’s blood vessels can be a target of the immune system. In conditions like systemic lupus erythematosus, the immune attack can cause retinal vasculitis, an inflammation of the retinal blood vessel walls that weakens them and leads to hemorrhage.18PubMed Central. Case Report: Concurrent retinal vasculitis and optic neuritis in systemic lupus erythematosus Infections can do the same thing. Tuberculosis, syphilis, cytomegalovirus, and toxoplasmosis are all known to produce inflammatory changes in the retinal vessels, as are non-infectious conditions like sarcoidosis and Behçet’s disease.19PubMed. Retinal vascular inflammatory and occlusive changes in infectious and non-infectious uveitis In these cases, the eye hemorrhage is really a downstream symptom of a systemic disease, and treating the underlying condition is the only way to stop recurrence.
Severe Nearsightedness
Pathological myopia, meaning extreme nearsightedness where the eyeball has elongated well beyond its normal shape, creates structural problems in the back of the eye. The stretching thins the retina and the layers beneath it, sometimes producing cracks in a structure called Bruch’s membrane.20PubMed Central. Lacquer cracks in pathological myopia: a clinical review These cracks can allow abnormal blood vessels to grow through, mimicking the same process seen in wet macular degeneration but in younger patients. The hemorrhages tend to be smaller and are sometimes the first sign that nearsightedness has progressed to a point where the eye’s structural integrity is compromised.
Retinal Hemorrhages in Children
Retinal hemorrhages in young children occupy a sensitive clinical space because of their association with abusive head trauma (formerly called shaken baby syndrome). In a study of children suspected of abuse, the presence of retinal hemorrhage carried an age-adjusted odds ratio of about five for abuse versus accidental injury across all ages, and in infants under six months, that figure rose to nearly twelve.21PubMed Central. Odds of abuse associated with retinal hemorrhages in children suspected of child abuse The severity of the hemorrhage mattered too: the most severe hemorrhage scores were found exclusively in children who had been abused.
This does not mean every retinal hemorrhage in a child indicates abuse. Birth-related retinal hemorrhages are common in newborns and usually resolve within weeks. Accidental falls and rare blood disorders can also produce them. But when an infant presents with extensive, multi-layered retinal hemorrhages without a clear medical explanation, it raises a red flag that prompts further investigation.
How the Blood Gets Diagnosed
When blood fills the vitreous, the eye becomes opaque to standard examination. Ultrasound imaging becomes the primary tool, allowing doctors to see through the blood and check for retinal detachment or masses behind the hemorrhage. When the eye’s media are still relatively clear, optical coherence tomography provides detailed cross-sectional images that show exactly where the blood sits in relation to the retina’s layers.22Eye. Imaging the vitreous: optical coherence tomography and ultrasound imaging
Figuring out the cause often requires looking beyond the eye. Blood tests for clotting disorders, blood sugar levels, inflammatory markers, and blood pressure measurements are all standard parts of the workup. In older patients, one condition that sometimes mimics a more dangerous diagnosis is peripheral exudative hemorrhagic chorioretinopathy, a degenerative bleeding process in the peripheral retina that can look enough like a choroidal tumor to prompt a referral for cancer.23PubMed. Peripheral exudative hemorrhagic chorioretinopathy simulating choroidal melanoma in 173 eyes In a review of 173 eyes, every single case had been referred for possible choroidal melanoma. Distinguishing between a hemorrhagic degeneration and a tumor matters enormously, since one is managed with observation and the other may require radiation or surgery.
Treatment Depends on the Cause and Location
Small vitreous hemorrhages, particularly those caused by posterior vitreous detachment or Valsalva retinopathy, often resolve without intervention as the eye gradually reabsorbs the blood over weeks to months. Your doctor may recommend sleeping with your head elevated to help the blood settle below the visual axis.
For subretinal hemorrhage from wet macular degeneration, the standard treatment is anti-VEGF injections, drugs that block the growth signal driving abnormal vessel formation. These injections have been shown to significantly improve vision in eyes with large subretinal hemorrhages, with one study reporting meaningful visual gains at twelve months.24Eye. Intravitreal anti-vascular endothelial growth factor monotherapy for large submacular hemorrhage secondary to neovascular age-related macular degeneration A systematic review comparing anti-VEGF injections to surgery for macular degeneration-related subretinal hemorrhage found similar visual outcomes between the two approaches, with injections preferred for less severe bleeds and surgery reserved for larger hemorrhages.25PubMed. Efficacy and Safety of Anti-VEGF Injections and Surgery for Age-Related Macular Degeneration-Related Submacular Hemorrhage: A Systematic Review and Meta-Analysis
When vitreous hemorrhage does not clear on its own, or when there is a risk of retinal detachment lurking behind the blood, vitrectomy surgery removes the blood-filled gel and replaces it with clear saline or a gas bubble. In diabetic patients, this surgery carries a known risk of rebleeding afterward, which is why surgeons typically address the underlying abnormal vessels with laser or anti-VEGF treatment during the same procedure.26PubMed. Postoperative vitreous hemorrhage after diabetic 23-gauge pars plana vitrectomy
Why Timing Matters for the Retina
Blood sitting against the retina is not just blocking light. It is actively harming tissue. As red blood cells break down, they release iron-containing compounds like hemosiderin that are toxic to the delicate photoreceptor cells and the pigment layer beneath them.8PubMed. A systematic review of the cell death mechanisms in retinal pigment epithelium cells and photoreceptors after subretinal hemorrhage – Implications for treatment options Animal studies have shown that small amounts of blood in the vitreous cavity can be tolerated without lasting damage, but beyond a certain volume, the iron deposition produces measurable retinal toxicity on both microscopic examination and electrical function testing.27PubMed. The toxicity of intravitreal whole blood and hemoglobin
This is the fundamental reason that any new episode of blood behind the eye warrants prompt evaluation. A small hemorrhage from a vitreous detachment may clear harmlessly, but a subretinal bleed from macular degeneration or a vitreous hemorrhage hiding a retinal tear can cause permanent damage if it sits too long. The cause determines the urgency, and the cause cannot be determined without an examination. If you notice a sudden shower of floaters, a dark curtain creeping across your vision, or a painless but dramatic drop in sight, getting seen within hours rather than days gives you the best shot at preserving the vision you have.