Subretinal hemorrhage is an eye condition characterized by bleeding that collects beneath the retina, the light-sensitive tissue at the back of the eye. This accumulation of blood can disrupt the normal function of the photoreceptors, the cells responsible for converting light into visual signals, potentially leading to vision loss. The severity of its impact on vision often depends on the extent and specific location of the bleeding within the subretinal space.
Understanding Subretinal Hemorrhage
Subretinal hemorrhage occurs when blood leaks from either the choroidal or retinal circulation and accumulates between the neurosensory retina and the retinal pigment epithelium (RPE). This blood creates a physical barrier, which can disrupt the exchange of nutrients and oxygen between the RPE and the photoreceptor cells, leading to their damage. This condition often involves the rupture of fragile blood vessels under the retina, allowing blood to leak into this delicate space.
A common underlying cause is neovascular age-related macular degeneration (nAMD), where abnormal, fragile blood vessels (choroidal neovascularization, CNV) grow beneath the retina and are prone to bleeding. Trauma to the eye, such as blunt injuries, can also lead to subretinal hemorrhage by causing choroidal ruptures. Vascular conditions like retinal artery macroaneurysms, which are abnormal dilations in retinal blood vessels, can rupture and cause bleeding. Systemic conditions affecting blood clotting or vessel integrity, such as certain blood dyscrasias, may also increase the risk of bleeding.
Recognizing the Signs and Diagnosis
Individuals experiencing subretinal hemorrhage often notice a sudden and painless loss of central vision. This can manifest as blurry vision, the appearance of dark spots or blind spots (scotomas), or distorted vision, where straight lines may appear wavy. These visual changes can occur rapidly.
Eye care professionals diagnose subretinal hemorrhage using several specialized tools. Ophthalmoscopy allows the doctor to view the back of the eye and identify the hemorrhage, which may appear as irregular, scalloped lesions ranging in color from dark red to gray-green. Optical coherence tomography (OCT) provides detailed cross-sectional images of the retina, allowing for precise localization and assessment of the hemorrhage’s thickness and its impact on retinal layers. Fluorescein angiography (FA) involves injecting a dye into the bloodstream, which then highlights blood vessels in the retina and choroid, helping to identify the source of bleeding, such as active neovascularization.
Treatment Approaches
Treatments for subretinal hemorrhage aim to clear the blood, reduce its damaging effects, and address the underlying cause. Medical management may involve observation for smaller hemorrhages, particularly if they are not directly impacting the macula. For subretinal hemorrhages associated with underlying nAMD, intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) agents are commonly used. These medications help to reduce the growth and leakage from abnormal blood vessels.
Surgical interventions are often considered for larger or more visually significant hemorrhages. Pneumatic displacement involves injecting an expansile gas bubble into the vitreous cavity to physically push the blood away from the fovea, the center of the macula. This procedure is frequently combined with intravitreal anti-VEGF therapy to treat the underlying pathology. Another surgical option is vitrectomy, a procedure that removes the vitreous gel from the eye. During vitrectomy, a recombinant tissue plasminogen activator (tPA) may be injected into the subretinal space to help dissolve the blood clot. The liquefied clot can then be removed.
Prognosis and Recovery
The prognosis for vision recovery after a subretinal hemorrhage varies considerably, influenced by factors such as the hemorrhage’s size, its exact location, the underlying cause, and how quickly treatment is initiated. Hemorrhages that are thicker often carry a worse prognosis. When the bleeding affects the macula, the central part of the retina responsible for sharp vision, the potential for long-term visual impact increases.
Damage to photoreceptor cells can occur rapidly due to various factors. While some vision recovery is possible, especially with timely intervention, permanent visual impairment can result if the hemorrhage is extensive or if a fibrotic scar forms. The recovery period can vary, and ongoing follow-up care is important to monitor the eye’s healing, manage any underlying conditions, and address potential complications like recurrent bleeding or scar formation.