Diabetic vitreous hemorrhage is the bleeding into the vitreous humor caused by advanced diabetic disease. The vitreous humor is the transparent gel-like material that fills the cavity between the eye lens and the light-sensitive spot at the back of the eyeball, the retina. Vitreous hemorrhage is one of the most common causes of sudden painless loss of vision. The blood can get into the humor through leakage/bleeding from abnormal new vessels or diseased retinal vessels, disruption of healthy retinal vessels, or through the retina from other sources. The effect on the patient's vision varies from blurriness and floaters to complete vision obscuration.
Diabetic patients can have eye disorders because of abnormalities in the network of blood vessels that supply the retina with oxygen and nutrients. The blood vessels can be closed or blocked, decreasing the flow of oxygen to the retina. The retina responds to the deprivation by growing new blood vessels, which are abnormal and fragile and unable to restore blood supply to the retina. The new abnormal retinal vessels expand into the vitreous and can rupture and leak into it, mainly if the vitreous pulls on them.
Causes & Risk Factors
The condition can occur due to three main issues:
- Healthy vessels that burst under stress
- Blood spreading from an adjacent source
- Abnormal retinal vessels susceptible to bleeding
Mechanical force can overcome the structural integrity of healthy blood vessels, causing them to rupture. Vitreous traction on the retinal blood network in a posterior vitreous detachment (PVD) can compromise a blood vessel. It's associated with a break or retinal tear in 70 to 95 percent of cases.
Abnormal retinal blood vessels arise from neovascularization because of ischemia in diabetic retinopathy. Inadequate oxygen supply to the retina induces vascular endothelial growth factor (VEGF) and other chemotactic elements to cause neovascularization. The new retinal blood vessels are prone to spontaneous bleeding because they lack tight endothelial junctions. Regular vitreous traction due to eye movement can rupture the vessels and stress caused by the contraction of the adjacent fibrous structure.
Bleeding from choroidal neovascularization, retinal microaneurysms, and tumors can spread through the epiretinal membrane into the vitreous.
Signs & Symptoms
Symptoms of the disorder vary depending on the extent of the bleeding. Patients with mild or early bleeding can experience a red hue, haze, floaters, shadows or cobwebs in their visual field. More significant bleeding can cause scotomas or limit fields of vision and visual acuity. Often, patients experience more reduced vision in the morning because blood gravitates to the eye's back during sleep, covering the macula.
The ophthalmologist will take the patient's complete medical history, including diabetes, trauma, surgery, etc. S/he will conduct a detailed eye examination, standard tests include:
- Blood tests
- Visual acuity test
- Slit-lamp biomicroscopy
- B-scan ultrasonography
- Dilated fundus examinations
- Intraocular pressure (IOP) Check
- Computer Tomography (CT) scan
- Indirect ophthalmoscopy with scleral depression
The doctor may first observe new cases that don't involve retinal detachment. Often, the blood clears spontaneously within several days to a few weeks to allow examination of the retina. S/he may also use intravitreal anti-VEGF agents such as bevacizumab, to induce neovascularization regression until laser photocoagulation is viable.
In other cases, the ophthalmologist may conduct laser pan-retinal photocoagulation to induce regression of neovascularization and help lower the risk of further bleeding/leakage. When the bleeding is over three months old, the surgeon may use vitrectomy surgery to remove the vitreous and most blood, which can decrease the chances of further bleeding if the vitreous was tugging on the abnormal blood vessels. Most ophthalmologists observe the condition for at least six months before performing a vitrectomy. Many surgeons also use pre-operative anti-VEGF agents before the surgery as regression of neovascular tissues decreases bleeding during and after the procedure.
The surgeon may use laser photocoagulation or anterior retinal cryotherapy to treat retinal tears.
Prognosis & Long-Term Outlook
Patients with diabetic vitreous hemorrhage have a poor prognosis for clearing the blood and regaining visual acuity. Where the bleeding leads to vision less than 5/200, most patients don't clear spontaneously even after one year.
Prevention & Follow Up
Patients should avoid strenuous activities because an increase in blood pressure can disrupt a clot leading to new active bleeding. The patient should also follow up with the ophthalmologist as directed. It enables him/her to evaluate the condition and determine the most appropriate course of action.