The phrase “blood behind the eye” describes a serious medical symptom that requires immediate investigation. This symptom refers to internal bleeding either within the eye structures (intraocular hemorrhage) or in the space immediately surrounding the eyeball (retrobulbar hemorrhage). Bleeding in these areas signals an underlying issue, ranging from chronic systemic disease to acute physical trauma. Understanding the cause is necessary for appropriate medical intervention, as failure to treat the root problem can lead to permanent vision loss.
Understanding Internal Eye Bleeding
When blood accumulates inside the eye, it most often collects in the vitreous cavity, the large space filled with the clear, jelly-like vitreous humor. This specific type of bleeding, termed a vitreous hemorrhage, impairs vision by blocking the path of light traveling toward the light-sensitive tissue at the back of the eye. Since the vitreous is normally clear, any blood present will scatter light and obstruct the image being formed on the retina.
Another common site for internal bleeding is the retina itself, resulting in a retinal or subretinal hemorrhage. The retina is a thin layer of nerve cells lining the back of the eye that converts light into neural signals. Bleeding can occur in multiple layers of the tissue or accumulate just beneath it, directly damaging the photoreceptor cells. The location significantly influences the severity and symptoms, with blood blocking the central vision causing the most immediate impairment.
Systemic Health Conditions as Primary Causes
Many instances of internal eye bleeding originate from chronic, body-wide diseases that compromise the integrity of the delicate ocular blood vessels. These systemic conditions often cause gradual damage to the vascular system before manifesting as a sudden hemorrhage. The most common cause of spontaneous intraocular bleeding in adults is related to complications of diabetes mellitus.
Uncontrolled blood sugar levels damage the tiny vessels of the retina, a condition known as diabetic retinopathy. In its advanced stage, the retina attempts to compensate for a lack of oxygen by growing new, abnormal blood vessels, a process called neovascularization. These newly formed vessels are prone to rupture and subsequent bleeding into the vitreous or onto the retinal surface.
Another significant systemic factor is long-standing high blood pressure, which leads to hypertensive retinopathy. Chronically elevated pressure strains the vessel walls, causing them to thicken and narrow, which can eventually lead to microaneurysms and vessel rupture. This constant pressure forces blood to leak from damaged arterioles and capillaries into the surrounding retinal tissue. Blood clotting disorders or the use of anticoagulant medications can also increase the susceptibility to vessel rupture and bleeding throughout the eye.
Localized Ocular Events and Injury
Bleeding can also be triggered by events isolated to the eye structure or by an external mechanical force. A common localized cause is a retinal tear or detachment, where the retina pulls away from its underlying support tissue. As the retina tears, it often severs small blood vessels that bridge the gap, leading to an immediate hemorrhage.
Vascular blockages within the eye also serve as a localized cause, specifically a Retinal Vein Occlusion (RVO). When a vein carrying blood away from the retina becomes blocked, pressure builds up rapidly in the upstream capillaries. This localized pressure increase forces blood to leak out from the vessels and into the retinal tissue or vitreous cavity. Trauma, such as a direct blow to the eye or orbit, is a leading cause of hemorrhage, especially in younger individuals.
Blunt force trauma can cause a rapid increase in pressure within the eye, which can mechanically damage or tear blood vessels in the retina or ciliary body. In a retrobulbar hemorrhage, blunt force can fracture the orbital walls, causing blood to accumulate in the confined space behind the eyeball. This accumulation quickly increases orbital pressure, which can compress the optic nerve.
Recognizing When to Seek Emergency Care
Any sudden change in vision accompanied by symptoms suggesting internal bleeding is considered a medical emergency, as delays in treatment can result in permanent vision loss. Patients with a vitreous hemorrhage often report numerous floaters, which may appear as black specks, cobwebs, or a dense cloud in their field of view. This can progress to blurred vision or a complete and rapid loss of sight, depending on the severity of the bleed.
A red tint to the vision can also be reported. When the bleeding is located behind the eyeball, such as in a retrobulbar hemorrhage, the symptoms are more severe and include intense pain behind the eye. Signs include the eye bulging outwards (proptosis) and a sudden, noticeable decrease in visual acuity. Immediate consultation with an eye care specialist or emergency services is necessary to diagnose the cause and prevent irreversible damage.