This study is conducted to evaluate the safety of a single intravitreal injection of THR-149.

Inclusion Criteria:

• Male or female aged 18 years or older
• Type 1 or type 2 Diabetes Mellitus
• Central-involved DME with central subfield thickness of ≥ 320µm on Spectralis® spectral domain optical coherence tomography (SD-OCT) or ≥ 305µm on non-Spectralis SD-OCT, in the study eye
• Best-corrected visual acuity (BCVA) ≤ 62 and ≥ 23 ETDRS letter score in the study eye
• Written informed consent obtained from the subject prior to screening procedures

Exclusion Criteria:

• Macular edema due to causes other than DME
• Concurrent disease in the study eye, other than central-involved DME, that could compromise BCVA, require medical or surgical intervention during the study period or could confound interpretation of the results
• Any condition that could confound the ability to detect a change in central subfield thickness in the study eye
• Previous confounding treatments / procedures, or their planned / expected use during the study period
• Presence of neovascularization at the disc (NVD) in the study eye
• Uncontrolled glaucoma in the study eye
• Any active ocular / intra-ocular infection or inflammation in either eye
• Poorly controlled Diabetes Mellitus
• Uncontrolled hypertension