This study is conducted to evaluate the safety of intravitreal THR-317 administered in combination with ranibizumab, and to assess the efficacy of the combination treatment in improving best-corrected visual acuity (BCVA) and reducing central subfield thickness (CST), in subjects with central-involved diabetic macular oedema (CI-DME).

Inclusion Criteria:

• Male or female aged 18 years or older
• Type 1 or type 2 Diabetes Mellitus
• CI-DME with central subfield thickness of ≥ 320μm on Spectralis® SD-OCT or ≥ 305μm on non Spectralis SD-OCT, in the study eye
• Anti-vascular endothelial growth factor (anti-VEGF) treatment naïve study eye, or poor or no response to prior treatment with ranibizumab in the study eye
• Reduced vision primarily due to DME, with BCVA ≤ 72 and ≥ 23 ETDRS letter score (≤ 20/40 and ≥ 20/320 Snellen equivalent) in the study eye
• Non-proliferative diabetic retinopathy of any stage in the study eye
• Written informed consent obtained from the subject prior to screening procedures

Exclusion Criteria:

• Concurrent disease in the study eye, other than CI-DME, that could compromise BCVA, require medical or surgical intervention during the study period or could confound interpretation of the results
• Previous confounding treatments / procedures, or their planned / expected use during the study period for up to 30 days after the last administration of study treatment
• Any active ocular / intraocular infection or inflammation in either eye
• Aphakic study eye
• Poorly controlled Diabetes Mellitus
• Uncontrolled hypertension
• Pregnant or lactating female, or female of child-bearing potential not utilising an adequate form of contraception, or male of reproductive potential not utilising contraception