Inclusion Criteria:

• For sexually active women of childbearing potential, use of an appropriate form of contraception (or abstinence) for the duration of the study

Ocular Inclusion Criteria (Study Eye)

• Foveal center-involved macular edema secondary to BRVO (including HRVO) or CRVO
• BCVA using ETDRS charts of 20/40 to 20/320 (Snellen equivalent) in the study eye

Exclusion Criteria:

• History of cerebral vascular accident or myocardial infarction within 3 months prior to Day 0
• History of any systemic anti-VEGF or pro-VEGF treatment within 6 months prior to Day 0
• History of allergy to fluorescein
• History of allergy to ranibizumab injection or related molecule
• Relevant systemic disease that may be associated with increased systemic VEGF levels. History of successfully treated malignancies is not an exclusion criterion.
• Uncontrolled blood pressure
• Pregnancy or lactation
• Daily use of oral corticosteroids to treat a chronic condition
• Required treatment with injectable corticosteroids to treat a musculoskeletal condition
• Participation in an investigational trial within 30 days prior to Day 0 that involved treatment with any drug or device that has not received regulatory approval at the time of study entry.

Ocular Exclusion Criteria (Study Eye)

• Prior episode of retinal vein occlusion (RVO)
• Brisk afferent pupillary defect
• History of any previous intravitreal anti-VEGF therapy for RVO in the study eye
• History of previous therapeutic treatment for RVO, other than anti-VEGF therapy, within 4 months prior to Day 0, including any intraocular corticosteroids
• History of previous surgical treatment for RVO, including radial optic neurotomy or sheathotomy
• History or presence of age-related macular degeneration (AMD) (dry or wet form)
• History of laser photocoagulation for macular edema within 4 months prior to Day 0
• History of panretinal scatter photocoagulation or sector laser photocoagulation within 4 months prior to Day 0 or anticipated within the next 4 months following Day 0
• History of pars plana vitrectomy
• History of intraocular surgery within 2 months prior to Day 0 or anticipated within the next 7 months following Day 0
• History of yttrium-aluminum-garnet (YAG) capsulotomy performed within 2 months prior to Day 0
• Previous filtration surgery in the study eye
• History of herpetic ocular infection
• History of ocular toxoplasmosis
• History of rhegmatogenous retinal detachment
• History of idiopathic central serous chorioretinopathy
• Evidence upon examination of vitreoretinal interface disease either on clinical examination or SD-OCT, thought to be contributing to macular edema
• Presence of an ocular condition that, in the opinion of the investigator, might affect macular edema or alter visual acuity during the study
• Visually significant hemorrhage obscuring the fovea and felt to be a major contributor to reduced visual acuity. The subject should be followed and when the hemorrhage in the fovea clears to the point that it is no longer a major contributor to reduced visual acuity, the subject may be screened for the study.
• Presence of a substantial cataract that, in the opinion of the investigator, is likely to be decreasing visual acuity by 3 lines or more
• IOP >= 30 mmHg. If a subject's IOP is >= 30 mmHg, that subject will be referred for glaucoma treatment and may be re-screened after 1 month.
• Evidence upon examination of pseudoexfoliation
• Aphakia
• Evidence upon examination of external ocular infection, including conjunctivitis, chalazion, or significant blepharitis
• Evidence upon examination of any diabetic retinopathy, defined as eyes of diabetic patients with more than one microaneurysm outside the area of the vein occlusion (inclusive of both eyes)
• Other relevant ocular disease that may be associated with increased intraocular VEGF levels