The vitreous humor lies between the lens and retina inside your eyes. Vision results from light rays passing through the transparent vitreous humor to form an image on the retina. Vitreous hemorrhage is the presence of blood in the vitreous humor. A small amount causes blurring of the vision. Large amounts of blood can make the vitreous humor opaque and cause near-complete vision loss.
The vitreous humor is composed of 99% water. The remaining is collagen and hyaluronic acid, which makes it semi-solid. The vitreous humor is transparent, about 4 milliliters in size, and occupies 80% of the space inside each eye.
What Is a Vitreous Hemorrhage?
Bleeding into the vitreous humor is a vitreous hemorrhage. Depending on the location of the blood, it is described as:
Preretinal. The blood lies in front of the retina. The vitreous humor is contained in a membrane. This membrane gets detached, and blood collects between it and the retina. The blood does not clot and may have a distinct upper level.
Intravitreal. The blood is mixed in the substance of the vitreous humor. Though dispersed in the gel, it may settle down because of gravity. The blood in the vitreous clots quickly, as the gel promotes platelet collection. The blood is red at first and changes to brown or yellow with time. The red blood cells (RBCs) remain intact for months and are broken down without being consumed by macrophages. The iron released by such RBC breakdown can damage the retinal cells.
Vitreous Hemorrhage Causes
Vitreous hemorrhage can happen because of local disorders of the eyes' structures as well as some diseases that affect the body.
Diabetes. This is the most common cause of vitreous hemorrhage, especially when both eyes are involved. New blood vessels develop on the retina, a condition called proliferative diabetic retinopathy. These vessels are fragile, and bleeding is frequent. The new vessel growth is caused by ischemia (reduced blood and oxygen supply) and stimulated by substances like vascular endothelial growth factor (VEGF) and insulin-like growth factor.
Trauma. Injuries are the most common cause of vitreous hemorrhage in people under 40 and are more common in males. The injury can be by blunt trauma (for example, a squash ball) or penetrating trauma.
Retinal tears and detachment. A tear in the retina may damage blood vessels, leading to bleeding. Permanent loss of vision can happen if not treated in time.
New blood vessels. Apart from diabetes, other conditions such as sickle cell disease, retinal vein occlusion, vasculitis (Eales disease and others), ocular ischemic syndrome, and retinopathy of prematurity also cause ischemia. VEGF and other factors stimulate the growth of new blood vessels that are fragile and bleed.
Normal blood vessel rupture. The normal blood vessels of the eye can also cause blood leakage when damaged. The vitreous humor is attached to the lens in the front and the retina at the back. Posterior vitreous detachment is the breakage of the attachment of the vitreous to the retina and causes bleeding. The bleeding may be preretinal or intravitreal.
Other causes. Neovascular age-related macular degeneration (AMD), idiopathic polypoidal choroidal vasculopathy (IPCV), retinal artery macroaneurysm, and valsalva retinopathy can cause vitreous hemorrhage. Eye surgery and some tumors can also cause such bleeding.
Anticoagulant medicines like aspirin and warfarin do not cause or worsen vitreous hemorrhage. You needn't stop these important drugs.
Vitreous Hemorrhage Symptoms
A vitreous hemorrhage can cause painless, near-complete loss of vision. This happens if there is enough blood to make the vitreous opaque. You may only be able to make out light and dark. Lesser amounts of hemorrhage can cause blurred vision. You may see dark spots, cobwebs, haze, shadows, or floaters. You might notice a streak of red color that spreads to fill your vision from that eye.
The vision loss is often worse in the morning because the blood has settled at the back of the eye. This covers the macula, the part of the retina that gives the sharpest vision.
Vitreous Hemorrhage Treatment
Vitreous hemorrhage is an urgent situation because it can cause permanent vision loss. You should go to your doctor or emergency room as soon as you notice any symptoms of this condition. An ophthalmologist's first step will be to check for a retinal tear or detachment that can cause permanent vision loss.
Your ophthalmologist will examine your eyes with a slit lamp for clues to the cause of the vitreous hemorrhage. They will also measure the pressure of your eyes (intraocular pressure, IOP) to detect glaucoma, retinal detachment, eyeball injury, or tumors. An examination of the inside of the eye with an ophthalmoscope is essential to detect retinal tears. If the vitreous is opaque and the retina can't be seen, you may need an ultrasound examination.
If there is no retinal tear or detachment, your ophthalmologist will ask you to wait. Vitreous hemorrhage gets resolved on its own over a few months. If the vitreous bleeding is very severe, your doctor may decide on surgery.
If the vitreous hemorrhage does not clear in 3 months, your doctor may advise surgery to restore normal vision. If both eyes are affected, your doctor may offer surgery earlier. Vitreous hemorrhage caused by trauma needs immediate surgery.
Vitreous Hemorrhage Surgery
Several surgical options are available, and your doctor will select the one most suited to your case.
Laser photocoagulation. A laser is used to seal the leaking vessel and any other new vessels. This is the treatment of choice in people with a proliferation of blood vessels.
Anterior retinal cryotherapy. Fresh retinal hemorrhage responds well to cryotherapy. The blood breaks down and is cleared sooner. However, this treatment causes inflammation and fibrin production and can lead to retinal detachment. It is suitable for people who have had a vitrectomy previously and have bleeding again.
Vitrectomy. Long-standing retinal hemorrhage is treated with vitrectomy. The entire vitreous humor is removed and replaced with a salt solution. The surgeon can then see the retina clearly and remove new vessels or foreign bodies. They can also repair retinal tears.
Intravitreal antiangiogenic injections. Bevacizumab and ranibizumab are medicines that oppose the production of VEGF. New vessel formation stops with this treatment, and further vitreous hemorrhage is prevented. This treatment is appropriate for vitreous hemorrhage caused by proliferative diabetic retinopathy.
