The purpose of this study is to determine whether ranibizumab (Lucentis) will be effective in reducing if not eliminating the macular edema associated with the disease, central retinal vein occlusion (CRVO).

Retinal Venous Occlusive disease is the second only to diabetic retinopathy as a major cause of blindness associated with retinal vascular disease. Macular edema is a major cause of vision loss in patients presenting with central and hemi vein occlusions. Until recently the standard of care for macular edema secondary to central retinal vein occlusion was observation. Recent investigations of steroids for this condition has shown greater visual benefit but is associated with risks such as cataract formation and increased intraocular pressure. In the past laser photocoagulation has been used, but was found to offer no visual benefits over the natural history in the treatment of macular edema associated with CRVO.

Ranibizumab (rhuFab V2), an anti-VEGF agent, is a potent inhibitor of vascular permeability, with the potential to reduce retinal vascular leakage and diminish macular edema. In addition, as an anti-VEGF agent, it may also inhibit neovascularization of the iris, a frequent complication of ischemic central retinal vein occlusion. Ranibizumab use as an intravitreal agent does carry the risk of intraocular infection but probably carries very low risk of glaucoma or cataract formation, making it a potentially safer pharmacologic treatment for CRVO associated macular edema as compared to steroids.

Inclusion Criteria:

• Ability to provide written informed consent and comply with study assessments for the full duration of the study
• Age > 18 years
• Clinical evidence of perfused central retinal vein occlusion. A central retinal vein occlusion (CRVO) is defined as an eye that has retinal hemorrhages and a dilated retinal venous system in all 4 quadrants. Other evidence of a CRVO may include telangiectatic capillary bed and collateral vessels at the optic nerve head.
• Central macular edema present on clinical examination and OCT testing with a central point thickness and/or central 1mm subfield thickness > 250 microns.
• Visual acuity score greater than or equal to 19 letters (20/400) and less than or equal to 73 letters (20/40) by the ETDRS visual acuity protocol.
• Media clarity, pupillary dilation and patient cooperation sufficient to allow OCT testing and retinal photography

Exclusion Criteria:

• Pregnancy (positive pregnancy test) or known to be pregnant; also pre-menopausal women not using adequate contraception.
• Participation in another ocular investigation or trial simultaneously
• Uncontrolled hypertension
• Any condition that, in the opinion of the investigator, would preclude participation in the study (e.g. chronic alcoholism, drug abuse)
• Significant diabetic retinopathy (greater than moderate NPDR) or macular edema associated with diabetic retinopathy
• Evidence of vitreoretinal interface abnormality after ocular exam or OCT that may be contributing to the macular edema
• An eye that, in the investigator's opinion, has no chance of improving in visual acuity following resolution of macular edema (e.g. presence of subretinal fibrosis or geographic atrophy)
• Presence of another ocular condition that may affect the visual acuity or macular edema during the course of the study (e.g. AMD, uveitis, Irvine-Gas)
• Evidence of neovascularization of the iris or retina (presence of ischemic CRVO)
• Evidence of central atrophy or fibrosis in the study eye
• Presence of substantial cataract, one that might decrease the vision by 3 or more lines of vision at sometime during the study.
• History of grid/focal laser or panretinal laser in the study eye
• History of vitreous surgery in the study eye
• History of use of intravitreal, peribulbar, or retrobulbar steroids within six months of the study.
• History of cataract surgery within 6 months of enrollment.
• History of YAG capsulotomy within 2 months of the surgery.
• Visual acuity <20/400 in the fellow eye
• Uncontrolled glaucoma (pressure >30) despite treatment with glaucoma medications.
• History of cerebral vascular accident or myocardial infarction within 3 months prior to Day 0.