Predictive factors for non-response to intravitreal bevacizumab in diabetic macular edema

To identify systemic, ocular, tomographic, and angiographic predictors of non-response to intravitreal bevacizumab (IVT) injections in patients with diabetic macular edema (DME).

This was a retrospective, cross-sectional, analytical study conducted at the Ophthalmology Department of the Internal Security Forces Hospital in La Marsa from January to December 2022. It included 154 patients with DME, divided into responders (54 eyes) and non-responders (100 eyes), all of whom received at least five consecutive IVT injections of bevacizumab. Clinical, laboratory, angiographic, and tomographic parameters were analyzed to assess their impact on treatment response.

Among the 154 patients (mean age: 65.3±8.6 years; 63% male), 100 (65%) were classified as non-responders. These patients had a longer duration of diabetes (P=0.012), higher HbA1c levels (9.4 vs. 8.7%, P=0.034), higher body mass index (BMI) (P<0.001), and higher mean arterial pressure (P<0.001) than the responders. OCT revealed significantly greater initial central macular thickness and macular volume (P=0.007; P<0.001), more frequent presence of disorganization of inner retinal layers (DRIL) (P<0.001), and disruption of the IS/OS and ELM lines (P<0.001) in non-responders. Fluorescein angiography showed a higher prevalence of macular ischemia in non-responders (P=0.005). Multivariate analysis identified IS/OS disruption (OR=48.03, P=0.043), increased macular volume (OR=3.77, P=0.006), and macular ischemia (OR=7.15, P=0.006) as independent predictors of non-response. Pseudophakia was independently associated with better response (OR=0.038, P=0.003).

Non-response to IVT bevacizumab in DME is associated with poor glycemic control, elevated BMI, and several structural (macular volume, DRIL, outer retinal layer disruption) and angiographic biomarkers. Early identification of these predictors may help guide therapeutic decision-making.