The aim of the trial is to evaluate the efficacy and safety of intravitreal injections of ranibizumab for the treatment of macular edema due to BRVO if the re-treatment regimen is guided by morphological macular changes detected by OCT compared to re-treatment according to SmPC defined re-treatment criteria (in case of increase of CRT and concomitant decrease of BCVA).

In a prospective, randomized, interventional, controlled phase IIb clinical the functional results of treatment with ranibizumab in patients with macular edema due to branch retinal vein occlusion when given according to morphological changes detected by OCT compared to standard re-treatment criteria according to SmPC

Inclusion Criteria:

• Recurrence of macular edema defined as any kind of fluid accumulation in the macula (microcystic changes with or without increase of central retinal thickness) detected by OCT in the month 1 to 6 after the last Lucentis injection without any decrease of BCVA measured with ETDRS charts 2. Diagnosis of BRVO with macular edema treated with at least three intravitreally applied injections of ranibizumab after the up-load phase of treatment 3. Age ≥ 18 years 4. Ability and willingness to attend all scheduled visits and assessments 5. For sexually active women of childbearing potential, use of an appropriate form of contraception (or abstinence) for the duration of the study

Exclusion Criteria:

1. Macular edema due to another etiology than retinal vein occlusion (e.g. diabetic maculopathy, uveitis, age related macular degeneration, Irvine-Gass syndrome)
2. Evidence upon examination of vitreoretinal interface disease (e.g., vitreomacular traction, epiretinal membrane), either on clinical examination or OCT, thought to be contributing to macular edema
3. Use of intraocular or periocular injection of steroids in the study eye (e.g., triamcinolone) prior to study entry
4. History of cerebral vascular accident, myocardial infarction, transient ischemic attacks in last 6 months
5. Pregnancy (positive pregnancy test) or lactation
6. History of allergy to humanized antibodies or any component of the ranibizumab formulation