A vitreous hemorrhage is defined by the presence of blood within the vitreous humor, the clear, gel-like substance that fills the large cavity at the back of the eye. This bleeding can range from a few scattered cells causing minor visual disturbances to a dense clot that results in a sudden and profound loss of sight. This condition requires prompt medical attention to identify and manage the underlying cause, as the blood impairs vision by obstructing light from reaching the retina.
Understanding the Vitreous and Bleeding Mechanism
The vitreous humor is a clear, gelatinous material that occupies roughly 80% of the eye’s volume, situated between the lens and the retina. Composed of nearly 99% water, this transparent gel allows light to pass unimpeded to the retina, helps the eyeball maintain its spherical shape, and supports the retina.
A vitreous hemorrhage occurs when blood vessels, most commonly those on the surface of the retina, rupture. When blood leaks into the vitreous cavity, it clouds the clear gel. This obstruction prevents light from properly focusing onto the retina, causing sudden vision loss or blurring.
Primary Causes of Hemorrhage
The most frequent underlying cause of vitreous hemorrhage in adults is Proliferative Diabetic Retinopathy (PDR), an advanced stage of diabetic eye disease. Due to chronic high blood sugar, the retina experiences a lack of oxygen, which triggers the release of vascular endothelial growth factor (VEGF). This chemical messenger stimulates the growth of new, fragile, and abnormal blood vessels, known as neovascularization, which grow onto the vitreous surface and easily rupture.
Another common cause is the mechanical tearing of blood vessels associated with a Posterior Vitreous Detachment (PVD). As people age, the vitreous gel naturally liquefies and shrinks, separating from the retina. If the gel is abnormally adherent, this separation exerts traction, pulling on and tearing a retinal blood vessel as it detaches. This traction can also lead to a more serious retinal tear or a full retinal detachment, where the bleeding is an immediate symptom.
Trauma is the leading cause of vitreous hemorrhage in younger individuals, resulting from direct blunt force or penetrating injuries that damage the eye’s internal structures and blood vessels. Retinal Vein Occlusions (RVOs), which block the outflow of blood, also cause ischemia and subsequent neovascularization, similar to diabetic retinopathy. Less common causes include macroaneurysms, which are small, balloon-like bulges on retinal arteries that can burst.
Symptoms, Diagnosis, and Treatment Options
The symptoms of a vitreous hemorrhage vary depending on the extent of the bleeding, but they are almost always sudden and painless. A patient may initially notice a sudden shower of fine floaters that look like cobwebs or dark specks moving across the vision. A more significant hemorrhage can cause the entire visual field to become hazy or cloudy, sometimes described as looking through a veil or stirred-up sediment.
In severe cases, the patient may experience significant or complete vision loss in the affected eye, often with a reddish or brownish tint to the remaining light perception. Diagnosis begins with a dilated eye examination to look for blood in the vitreous cavity. If the hemorrhage is too dense for the ophthalmologist to view the retina clearly, a B-scan ultrasound is performed to check for associated complications, such as a retinal detachment.
Treatment is tailored to the underlying cause and the density of the hemorrhage. For small or mild hemorrhages, the first approach is observation, allowing the body time to naturally reabsorb the blood, which can take several weeks or months. The patient may be advised to elevate their head while sleeping to help the blood settle lower in the eye’s cavity, potentially improving central vision.
If the underlying cause is neovascularization, such as from diabetic retinopathy, laser photocoagulation may be performed once the blood has cleared enough to allow a view of the retina. This procedure uses a laser to destroy the ischemic areas of the retina, which reduces the production of VEGF and causes the abnormal vessels to shrink. If the hemorrhage does not clear after observation, or if it is associated with a sight-threatening complication like a retinal detachment, a surgical procedure called a vitrectomy is necessary. During a vitrectomy, the surgeon removes the blood-filled vitreous gel and replaces it with a clear saline solution or gas bubble.
Recovery and Visual Prognosis
The recovery timeline is highly variable, depending on the volume of blood and the chosen treatment method. If managed conservatively, complete visual recovery may take two to three months as the blood slowly clears. Following a vitrectomy, the initial recovery period is faster, though full visual stabilization still takes time.
The long-term visual prognosis is determined by the health of the retina before the hemorrhage and the nature of the underlying cause. Outcomes are favorable for hemorrhages caused by PVD or minor trauma, provided no permanent damage occurred to the retina or macula. For chronic conditions like proliferative diabetic retinopathy, continuous monitoring and management are required to prevent recurrence and preserve vision.