Primary Outcome Measures:
- The primary objective is to determine the proportion of subjects in each group ( 0.3 and 0.5 mg ) gaining 15 or more letters at month 6 and 12 (ETDRS visual refraction at 4 meters) and to determine if a difference exists between the high and low dose. [ Time Frame: 6 and 12 months ] [ Designated as safety issue: No ]
Secondary Outcome Measures:
- To determine the safety and tolerability of ranibizumab in the treatment of macular edema associated with CRVO in each group [ Time Frame: 6 and 12 months ] [ Designated as safety issue: Yes ]
- To determine the proportion of subjects in each group gaining 15 or more letters at month 3, 6, 9 & 12 as compared to baseline (ETDRS visual refraction at 4 meters) and to determine if a statistically significant difference exists between the groups [ Time Frame: 3, 6, 9, and 12 months ] [ Designated as safety issue: No ]
- Change in central retinal thickness from baseline as measured by OCT at months 3, 6, 9 and 12 [ Time Frame: 3,6,9, and 12 months ] [ Designated as safety issue: No ]
- To determine the proportion of subjects in each group losing 15 or more letters at months 3,6,9,12 as compared to baseline (ETDRS visual refraction at 4 meters) and to determine if a statistically significant difference exists between the groups. [ Time Frame: 3, 6, 9, and 12 months ] [ Designated as safety issue: No ]
- To determine the proportion of subjects in each group losing 30 or more letter at months 3,6,8,12 as compared to baseline (ETDRS visual refraction at 4 meters) and to determine if a statistically significant difference exists between the groups. [ Time Frame: 3, 6, 9, and 12 months ] [ Designated as safety issue: No ]
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 abd hemi vein occlusions. Currently, there is no proven treatment to address macular edema in these patients. 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. Investigators have demonstrated in case reports that intravitreal triamcinolone (Kenalog) may result in the reduction in macular edema, leading to visual improvement in some patients with CRVO. Triamcinolone is relatively well tolerated in many patients, but its use is associated with significant risk of elevated intraocular pressure, cataract, and intraocular infection.
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 triamcinolone.