Preretinal Hemorrhage: Causes, Symptoms, and Treatment
Understanding Preretinal Hemorrhage
A preretinal hemorrhage occurs when blood becomes trapped in the small space between the retina and the vitreous gel or the internal limiting membrane (ILM). The ILM is a thin tissue layer on the surface of the retina. This condition is also called a subhyaloid hemorrhage. Because the blood pools in a confined pocket, it often settles into a characteristic boat shape or D shape when viewed during an eye exam.
The blood sitting in front of the retina blocks light from reaching the light-sensitive cells beneath it. This causes the sudden blurring or darkening of vision that many people experience. The severity of vision loss depends on the size and location of the hemorrhage. Hemorrhages that cover the macula, the central part of the retina responsible for detailed vision, tend to cause the most significant symptoms.
Bleeding in front of the retina generally happens through one of three mechanisms. The most common involves abnormal blood vessels that are fragile and prone to breaking. The second involves normal blood vessels that rupture under sudden physical stress. The third involves blood spreading from a nearby source within the eye.
In conditions like diabetic retinopathy, the retina does not receive enough oxygen. The eye responds by producing vascular endothelial growth factor (VEGF) and other chemical signals. These signals trigger the growth of new blood vessels, a process called neovascularization. These new vessels lack strong walls, making them very likely to leak or bleed spontaneously.
In some cases, preretinal hemorrhage results from a sudden spike in pressure inside the body. This is known as Valsalva retinopathy. It happens when a person strains forcefully against a closed airway. Common triggers include heavy lifting, intense coughing, vomiting, or straining during a bowel movement.
This straining reduces blood flow returning to the heart and raises pressure in the veins of the upper body, including those in the eye. The increased pressure can cause small, delicate capillaries near the macula to rupture. Blood then leaks into the preretinal space.
Who Is Affected and Risk Factors
Several health conditions increase the chance of developing a preretinal hemorrhage. The most significant risk factors include the following:
- Diabetes, particularly when it has led to proliferative diabetic retinopathy
- High blood pressure (hypertension)
- High cholesterol (hyperlipidemia)
- Atherosclerosis (hardening and narrowing of arteries)
- Blood disorders or use of blood-thinning medications
- History of eye trauma or injury
Proliferative diabetic retinopathy is the most frequent cause of vitreous hemorrhage in adults in the United States, accounting for 31.5 to 54 percent of cases (Medscape, 2024). In advanced diabetic eye disease, up to 15 to 20 percent of patients may develop this type of bleeding (Specialty Vision, 2024). The fragile new blood vessels that grow in response to retinal ischemia are the primary source of hemorrhage in these patients.
Retinal vein occlusion (a blockage in the veins that drain blood from the retina) can also lead to neovascularization and subsequent preretinal hemorrhage. Sickle cell retinopathy, ocular ischemic syndrome, and retinopathy of prematurity are additional conditions that can trigger the growth of abnormal, fragile vessels.
Terson syndrome, which involves bleeding inside the eye following a brain hemorrhage, is another recognized cause. Older adults face higher risk because the vitreous gel naturally changes and separates from the retina with age. Vitreous hemorrhage has an overall incidence of seven cases per 100,000 people, making it one of the most common causes of sudden or rapidly worsening vision loss (AAO EyeNet, 2024).
Signs and Symptoms
The most common symptom of a preretinal hemorrhage is sudden blurring or cloudiness in one eye. Many people describe the experience as looking through fog, a veil, or a reddish haze. The severity depends on the amount of blood present and whether it covers the central retina. A small hemorrhage off to one side may cause only mild blurring. A large hemorrhage over the macula can cause significant vision loss.
A sudden shower of new floaters is a hallmark symptom. These may appear as dark spots, lines, or web-like shapes drifting across your vision. They are caused by tiny clumps of blood floating within the eye. A sudden increase in floaters is a warning sign that requires prompt attention.
Some people also notice brief flashes of light, particularly in their peripheral vision. These flashes may look like camera flashes or lightning bolts. They occur when the vitreous gel tugs on the retina.
Certain symptoms require immediate evaluation by a retina specialist or an emergency room visit. See a retina specialist or go to the emergency room immediately if you experience a sudden increase in floaters, flashes of light, a curtain or shadow spreading across your vision, or sudden vision loss in one eye. These symptoms may indicate a preretinal hemorrhage, a retinal tear, or a retinal detachment. Prompt treatment is essential to protect your vision.
Diagnosis and Testing
A retina specialist will begin with a comprehensive dilated eye exam. Drops are placed in the eye to widen the pupil, allowing the specialist to see the retina and the space in front of it clearly. A preretinal hemorrhage often has a distinctive appearance: a flat, boat-shaped pocket of blood sitting in front of the retina. If the blood is fresh and still liquid, a visible fluid level may be seen as the blood settles with gravity.
Several imaging techniques help confirm the diagnosis and evaluate the underlying cause. Optical coherence tomography (OCT) uses light waves to create detailed cross-sectional images of the retina. OCT can show exactly where the blood is located. It can distinguish whether blood sits between the vitreous and the ILM or between the ILM and the retinal nerve fiber layer.
Fluorescein angiography may also be performed. In this test, a special dye is injected into a vein in the arm. Photographs are taken as the dye travels through the blood vessels of the retina. This test can reveal leaking vessels, areas of neovascularization, or blocked vessels that may have caused the hemorrhage.
If the hemorrhage is large enough to block the view of the retina, an ultrasound (B-scan) of the eye may be used. This test uses sound waves to create an image of the structures inside the eye. It helps rule out a retinal detachment or other serious conditions that may be hidden behind the blood.
Treatment Options
In many cases, a preretinal hemorrhage will resolve on its own as the body gradually reabsorbs the blood. A study of 58 eyes found that the mean hemorrhage clearance time with observation alone was approximately 99 days (Specialty Vision, 2024). During this period, a retina specialist may recommend avoiding blood-thinning medications when it is medically safe to do so. Limiting strenuous physical activity may also help reduce the risk of rebleeding.
No medication taken by mouth has proven to speed up the clearance of a preretinal hemorrhage. Regular follow-up visits are important during the observation period. These visits allow the retina specialist to monitor progress and check for complications such as retinal detachment.
For larger hemorrhages, especially when they affect the only eye with useful vision, a procedure called Nd:YAG laser membranotomy may be considered. In this procedure, a laser creates a small opening in the membrane trapping the blood. This allows the blood to drain into the vitreous cavity, where it disperses and clears more rapidly.
This procedure works best when performed within about one month of symptom onset. After that time, the blood tends to clot, making it resistant to laser drainage. A krypton laser may be used as an alternative in some cases.
When a preretinal hemorrhage is dense, does not improve with observation, or is accompanied by other complications, pars plana vitrectomy (a surgery to remove the vitreous gel from the eye) may be recommended. During this procedure, the retina specialist removes the vitreous gel along with the trapped blood. It is replaced with a clear saline solution or a gas bubble.
Vitrectomy dramatically speeds recovery. The same study showed that vitrectomy patients experienced clearance in an average of 4.5 days (Specialty Vision, 2024). This surgery also allows the retina specialist to directly treat underlying problems, such as sealing leaking blood vessels with laser during the same operation.
When preretinal hemorrhage is caused by neovascularization from conditions like diabetic retinopathy or retinal vein occlusion, anti-VEGF injections may be used. Medications such as Eylea (aflibercept), Lucentis (ranibizumab), or Avastin (bevacizumab), which is used off-label for eye conditions, block the chemical signals that drive abnormal blood vessel growth.
In some cases, anti-VEGF therapy has been used to treat specific causes of preretinal hemorrhage. For example, in patients with retinal artery macroaneurysm, intravitreal bevacizumab resulted in gradual clearance of the hemorrhage and improvement in vision over several weeks. These injections are typically given every 4 to 8 weeks depending on the medication and the patient's response.
What to Expect
The timeline for visual recovery depends on the size of the hemorrhage, its location, the treatment approach, and the underlying cause. Small hemorrhages that do not cover the macula may clear within a few weeks with observation alone. Larger hemorrhages may take three months or longer to resolve without intervention.
Patients who undergo Nd:YAG laser membranotomy often notice rapid improvement in vision within days. The blood disperses into the vitreous cavity and is gradually absorbed. Those who undergo vitrectomy typically experience the fastest visual recovery, with significant clearing within the first week after surgery.
Regular follow-up appointments with a retina specialist are essential regardless of the treatment approach. These visits allow the specialist to monitor hemorrhage clearance, check for recurrence, and manage the underlying condition.
For patients with diabetic retinopathy or retinal vein occlusion, ongoing treatment of the underlying condition is critical. This may include continued anti-VEGF injections, laser treatment, or both. Managing blood sugar, blood pressure, and cholesterol also plays a major role in preventing future episodes.
While many preretinal hemorrhages resolve without lasting damage, complications can occur. Prolonged contact between the blood and the retina may lead to toxic effects on the retinal cells. This can potentially cause some degree of lasting vision changes. In rare cases, the hemorrhage may organize into scar tissue that can pull on the retina and increase the risk of retinal detachment.
Repeated episodes of bleeding suggest that the underlying vascular condition is not well controlled. This reinforces the importance of treating the root cause and maintaining regular eye care.
Living With Preretinal Hemorrhage
During the recovery period, you may need to make adjustments to your daily routine. Your retina specialist may advise you to avoid heavy lifting, straining, and high-intensity exercise until the hemorrhage has cleared. These activities can raise pressure inside the eye and increase the risk of rebleeding.
If vision in the affected eye is significantly reduced, take extra precautions with tasks that require depth perception, such as driving or navigating stairs. Use good lighting when reading or working on detailed tasks.
Because preretinal hemorrhage is closely tied to systemic health conditions, managing those conditions is one of the most effective ways to reduce recurrence risk. For people with diabetes, keeping blood sugar levels within the target range recommended by their doctor is essential. Consistent blood pressure management and cholesterol control also help protect the blood vessels in the retina.
Work closely with your primary care provider and your retina specialist to create a coordinated care plan. Taking prescribed medications, following dietary recommendations, and staying physically active within safe limits all contribute to better outcomes.
Even after a preretinal hemorrhage has resolved, long-term monitoring by a retina specialist is important. Conditions like diabetic retinopathy and retinal vein occlusion are chronic and can lead to recurrent episodes of bleeding. Regular dilated eye exams, typically every three to six months depending on your condition, allow early detection of new abnormal blood vessel growth or other changes.
When to See a Retina Specialist
See a retina specialist or go to the emergency room immediately if you experience any of the following symptoms:
- A sudden increase in floaters or dark spots in your vision
- Flashes of light in one or both eyes
- A shadow or curtain spreading across part of your visual field
- Sudden, significant vision loss in one eye
If you have diabetes, high blood pressure, a history of retinal vein occlusion, or other risk factors for retinal vascular disease, regular eye exams with a retina specialist are important. Many conditions that cause preretinal hemorrhage develop gradually. They can be detected and treated before bleeding occurs.
Early detection and treatment of neovascularization with anti-VEGF injections or laser therapy can significantly reduce the risk of a preretinal hemorrhage.
Questions and Answers
In many cases, vision improves significantly once the blood clears. However, lasting vision changes can occur if the hemorrhage is large, if it sits over the macula for an extended period, or if the underlying condition has caused retinal damage. The longer the blood remains in contact with the retinal cells, the greater the chance of some lasting effect. Early evaluation and appropriate treatment can help minimize this risk.
Without treatment, the average clearance time is approximately 99 days, or about three months (Specialty Vision, 2024). Smaller hemorrhages may resolve faster, while larger ones may take longer. If the hemorrhage is not clearing or is affecting your only functional eye, your retina specialist may recommend laser membranotomy or vitrectomy to speed up the process.
There is no proven home remedy or over-the-counter medication that speeds up the absorption of a preretinal hemorrhage. Your retina specialist may suggest sleeping with your head slightly elevated. Avoiding activities that significantly raise pressure in your body, such as heavy lifting or straining, may also help. Following your doctor's instructions for managing diabetes, blood pressure, and other underlying conditions is the most helpful step you can take at home.
Not all preretinal hemorrhages require surgery. Many resolve with observation alone. Surgery, specifically pars plana vitrectomy, is typically reserved for cases where the hemorrhage is dense, does not improve over time, or significantly impairs vision. Nd:YAG laser membranotomy is a less invasive option that may be appropriate if performed within the first month. Your retina specialist will recommend the best approach based on the size, location, and duration of the hemorrhage as well as the health of your other eye.
Yes. If the underlying cause of the hemorrhage is not treated or well controlled, bleeding can recur. This is especially true for people with proliferative diabetic retinopathy, retinal vein occlusion, or uncontrolled high blood pressure. Ongoing management of the underlying condition and regular follow-up with a retina specialist are the best strategies for reducing the risk of another episode.