Central retinal vein occlusion (CRVO) occurs when the main blood vessel that transports blood away from the retina (the very back portion of the eye) becomes blocked, causing the leakage of fluid into the retina and thereby causing a swelling of the macula (the portion of the retina responsible for fine vision). This swelling is called macular edema. When the macula swells with fluid, central vision becomes blurry. The study drug aflibercept has been shown to reduce the amount of fluid and blood leaked into the retina. It can help to stabilize, and in many cases, improve the vision loss related to CRVO. Aflibercept has been approved for the treatment of macular edema secondary to CRVO in the United States (US), European Union (EU), Japan, and other countries.

The study was considered research because, although the study drug was already on the market for macular edema secondary to CRVO, there were no studies available that addressed the questions of what were useful intervals for treating and assessing patients, how did they differ among patients, and how were criteria applied for retreatment. The purpose of this study was to evaluate the effectiveness, treatment interval, and safety of the treatment regimen (pattern for administering treatment) in subjects with macular edema secondary to CRVO. In addition, this study explored new imaging methods for assessing the affected eye.

Inclusion Criteria:

• Center-involved macular edema secondary to CRVO for no longer than 3 months (at the screening visit it should be ensured that the subjects will comply with the criterion of ≤ 3 months since onset of macular edema at their scheduled baseline visit).
• Adult subjects diagnosed with macular edema secondary to CRVO who are scheduled to be treated with IVT aflibercept as per investigator's routine treatment practice with the intent to use a T&E regimen after initial dosing.
• Treatment-naïve subjects for macular edema secondary to CRVO.
• Men and women ≥ 18 years of age.
• Documented BCVA of ETDRS letter score of 73 to 24 letters (Snellen equivalent of 20/40 to 20/320) in the study eye.

Exclusion Criteria:

• Previous PRP or macular laser photocoagulation in the study eye.
• Any prior or concomitant ocular treatment (e.g. anti-VEGF therapy, corticosteroids) in the study eye for macular edema secondary to RVO, except dietary supplements or vitamins prior to inclusion in the study. Intraocular anti-VEGF treatment is permitted for the treatment of diseases of fellow eye except for those that are specifically excluded.
• Prior systemic anti-VEGF or corticosteroid therapy, investigational or approved, within the last 3 months before the first dose in the study.
• Previous use of intraocular corticosteroids in the study eye at any time or use of periocular corticosteroids in the study eye within 12 months prior to Day 1.
• Any active intraocular, extraocular, and periocular inflammation or infection in either eye within 4 weeks of screening.
• Any history of allergy to povidone iodine.
• Known serious allergy to the fluorescein sodium for injection in angiography.
• Presence of any contraindications indicated in the EU commission/locally approved label for IVT aflibercept: hypersensitivity to the active substance IVT aflibercept or to any of the excipients; active or suspected ocular or periocular infection; active severe intraocular inflammation.