This patient has suffered a central retinal vein occlusion (CRVO). The symptoms of sudden painless vision loss and the “blood and thunder” appearance of the retina (as seen in the picture) is typical of this diagnosis. Other diseases to consider include diabetic retinopathy, central retinal artery occlusion, retinopathy of anemia or leukemia or traumatic retinopathy (ex. shaking baby syndrome).
CRVO is the result of a blockage of the central retinal vein; most likely at the level of the lamina cribosa. Typical retinal findings include diffuse intraretinal hemorrhages, retinal edema, and dilated tortuous retinal veins. Cotton wool spots, optic nerve edema and hemorrhages, and the subsequent development of neovascularization of the iris, optic nerve or retina can also be seen. CRVO can be classified into two broad categories: perfused (the most common type) or ischemic/non-perfused. Generally, perfused CRVO is a milder form of the disease, presenting with a better visual acuity and resulting in better final visual acuity and a decreased likelihood of iris or retinal neovascularization than ischemic/non-perfused CRVO. However, up to 1/3 of perfused CRVO may progress to the ischemic form. Some patients present with an intermediate form difficult to categorize. Vision loss due to CRVO can be due to macular edema, macular ischemia or complications from neovascularization including neovascular glaucoma or vitreous hemorrhage.
Risk factors for CRVO include systemic hypertension, diabetes mellitus, vasculopathy and primary open angle glaucoma. A typical patient is male and 50 yrs or older. A comprehensive medical history is necessary to identify any risk factors and aid in referring to the appropriate medical care provider. Younger patients should also be evaluated for hypercoagulable states, other vascular diseases and the use of OCPs, in addition to the above. An initial ophthalmic examination may include a fluorescein angiogram to determine the degree of ischemia/perfusion – although interpretation is hindered by the amount of retinal hemorrhages. Monthly examinations to include visual acuity, pupil check for APD and examination of the anterior segment angle for neovascularization for the first 3-6 months after diagnosis are necessary to identify cases of ischemic CRVO and of neovascularization that might require treatment.
Treatment: Patients developing ocular neovascularization need panretinal photocoagulation to prevent further complications. Macular edema associated with CRVO does not respond well to focal grid laser treatment, with visual acuity outcomes similar to those receiving no treatment. Treatment with intravitreal steroids or an anti-VEGF medication (ex. Avastin) have shown promising results. Patients may consider starting a daily aspirin if they are not already on this.
The prognosis varies depending on whether the CRVO was perfused or not perfused. 50% of patients with perfused CRVO will have vision worse than 20/200 compared to 90% of non-perfused CRVO patients. A major complication of non-perfused CRVO is neovascularization which occurs in approximately 60% of patients. Risk of other eye involvement is approx. 5%.