The vitreous humor is the clear, gel-like substance that fills the large cavity in the center of the eye, situated between the lens and the retina. A vitreous hemorrhage (VH) occurs when blood leaks into this gel-filled space, clouding the normally clear substance. This event is typically a complication of an underlying eye condition or injury that causes fragile or damaged blood vessels to rupture. Because a vitreous hemorrhage can significantly impact sight and often signals a serious problem in the back of the eye, it requires prompt attention from an eye specialist.
What Leads to Bleeding in the Eye
The most frequent cause of blood leaking into the vitreous space is proliferative diabetic retinopathy (PDR). In PDR, diabetes damages retinal blood vessels, leading to oxygen starvation (ischemia). The retina responds by releasing vascular endothelial growth factor (VEGF), which stimulates the formation of new, abnormal blood vessels.
These newly formed vessels (neovascularization) are extremely fragile and prone to spontaneous rupture and bleeding into the vitreous cavity. The second major mechanism involves the sudden mechanical tearing of normal retinal vessels, often due to movement of the vitreous gel. As people age, the vitreous naturally begins to liquefy and separate from the retina in a process called posterior vitreous detachment (PVD).
If the vitreous is abnormally adherent to the retina, this separation can exert traction, tearing a retinal vessel or causing a full retinal tear, leading to bleeding. Ocular trauma, such as a blunt injury to the eye, is another significant cause, particularly in younger patients. Less common causes include retinal vein occlusions, macroaneurysms, and certain vascular diseases like sickle cell retinopathy.
How a Vitreous Hemorrhage Affects Vision
The symptoms experienced depend directly on the volume and density of the blood in the vitreous cavity. A small leak may only cause the sudden appearance of new floaters, which are shadows cast by the red blood cells drifting within the gel.
If the bleeding is more extensive, the visual disturbance escalates quickly because the blood physically blocks light from reaching the retina. Patients report a sudden, painless reduction in vision, ranging from blurry sight to near-total darkness. The diffused blood may also tint the field of vision with a red hue. The blood may take a significant amount of time to settle and be reabsorbed by the eye’s natural processes.
Clinical Evaluation and Management
The initial clinical evaluation involves a dilated eye examination using a slit lamp to confirm blood cells within the vitreous space. If the hemorrhage is dense, the blood prevents the clinician from viewing the underlying retina, making it impossible to determine the cause of the bleeding. When the view is obscured, B-scan ultrasonography becomes an important diagnostic tool.
This non-invasive imaging technique uses high-frequency sound waves to create a cross-sectional image of the eye’s internal structures, seeing past the opaque blood. The B-scan helps detect or rule out serious underlying complications, such as a retinal detachment or a large retinal tear, which require urgent surgical intervention. Based on the severity and B-scan findings, the eye specialist determines the appropriate management approach.
For small to moderate hemorrhages where no immediate retinal detachment is found, the initial treatment is often observation. Patients are advised to rest, keep their head elevated, and allow the blood to naturally clear over several weeks or months. The body’s natural mechanisms, including macrophage cells, work to break down and resorb the blood components.
If the hemorrhage is extremely dense, does not clear spontaneously, or is associated with a retinal tear or detachment, surgical intervention is necessary. The standard procedure for removing the blood and treating the underlying cause is a pars plana vitrectomy. During this surgery, the specialist makes tiny incisions in the sclera to access the vitreous cavity.
The bloody vitreous gel is carefully removed using a specialized cutting instrument. Once the blood is gone, the surgeon fully inspects the retina and addresses the source of the bleeding, often using a laser (endolaser) to seal off abnormal vessels or repair tears. The removed vitreous gel is then replaced with a clear solution, such as saline, or sometimes a gas bubble or silicone oil, which helps the eye maintain its shape and keeps the retina in its proper position.