AbstractObjectiveIntravitreal ranibizumab is one of the anti‐vascular endothelial growth factors used for the treatment of diabetic macular oedema, not always successfully. We aimed to identify the factors affecting the changes of central macular thickness after induction treatment with intravitreal ranibizumab, to predict the treatment effect and facilitate early treatment decisions.MethodsCross‐sectional study involving a retrospective record review of diabetic macular oedema patients who received an induction treatment of three monthly 0.5 mg intravitreal ranibizumab injections between 2016 and 2019. Central macular thickness was measured at baseline and 3 months post‐treatment. Linear regression was applied to identify the factors associated with the changes of central macular thickness.ResultsA total of 153 diabetic macular oedema patients were involved in this study. Their mean age was 57.5 ± 7.7 years, 54.9% were female. The mean change of central macular thickness from baseline to 3 months after completed induction treatment of intravitreal ranibizumab was 155.5 ± 137.8 μm. Factors significantly associated with changes of central macular thickness were baseline central macular thickness [b = 0.73; 95% (CI): 0.63, 0.84; p = <0.001] and presence of subretinal fluid [b = 35.43; 95% CI: 3.70, 67.16; p = 0.029].ConclusionThicker baseline central macular thickness and presence of subretinal fluid were the factors significantly associated with greater changes of central macular thickness in diabetic macular oedema patients after receiving three injections of intravitreal ranibizumab.