Inclusion Criteria:

• Diagnosis of diabetes mellitus (type 1 or type 2).
• Best corrected E-ETDRS visual acuity score of ≥ 24 letters (i.e., 20/320 or better) and ≤ 73 letters (i.e., 20/40 or worse).
• On clinical exam, definite retinal thickening due to diabetic macular edema involving the center of the macula.
• Retinal Thickness at the center point ≥ 250 microns.
• Media clarity, pupillary dilation, and patient cooperation sufficient for adequate fundus photographs.

Exclusion Criteria:

• History of any vitreous hemorrhage within 4 weeks prior to Visit 2 (Day 1).
• Macular edema due to causes other than diabetic macular edema. An eye should be considered ineligible: (1) if the macular edema is considered to be related to cataract extraction or (2) clinical exam and/or OCT suggests that vitreoretinal interface disease (e.g., a taut posterior hyaloid or epiretinal membrane) is the primary cause of the macular edema.
• An ocular condition is present such that, in the opinion of the investigator, visual acuity would not improve from resolution of macular edema (e.g., foveal atrophy, pigmentary changes, dense subfoveal hard exudates, nonretinal condition).
• An ocular condition is present (other than diabetes) that, in the opinion of the investigator, might affect macular edema or alter visual acuity during the course of the study (e.g., vein occlusion, age-related macular degeneration, uveitis or other ocular inflammatory disease, neovascular glaucoma, Irvine-Gass Syndrome, etc.).
• Presence of any other condition or laboratory abnormality, which, in the opinion of the Investigator, would interfere with the assessment of disease status/progression or jeopardize the patient's appropriate participation in this Phase 1 study.