A Study of Ranibizumab Injection in Subjects With Clinically Significant Macular Edema (ME) With Center Involvement Secondary to Diabetes Mellitus (RIDE)

Inclusion Criteria: * Willingness to provide written informed consent and, at U.S. sites, Health Insurance Portability and Accountability Act (HIPAA) authorization, and in other countries, as applicable according to national laws. * Age ≥ 18 years. * Diabetes mellitus (Type 1 or 2) . * Retinal thickening secondary to diabetes mellitus (DME) involving the center of the fovea with central macular thickness ≥ 275 µm in the center subfield as assessed on optical coherence tomography (OCT). * Best corrected visual acuity (BCVA) score in the study eye of 20/40 to 20/320 approximate Snellen equivalent using the Early Treatment Diabetic Retinopathy Study (ETDRS) protocol at an initial testing distance of 4 meters. * Decrease in vision determined to be primarily the result of DME and not to other causes. * For sexually active women of childbearing potential, use of an appropriate form of contraception (or abstinence) for the duration of the study. * Ability (in the opinion of the investigator) and willingness to return for all scheduled visits and assessments. Exclusion Criteria: * History of vitreoretinal surgery in the study eye. * Panretinal photocoagulation (PRP) or macular laser photocoagulation in the study eye within 3 months of screening. * Previous use of intraocular corticosteroids in the study eye (eg, triamcinolone acetonide \[TA\]) within 3 months of screening. * Previous treatment with anti-angiogenic drugs in either eye (pegaptanib sodium, anecortave acetate, bevaciz…