Biomarkers of risk of switching to dexamethasone implant for the treatment of diabetic macular oedema in real clinical practice: a multicentric study

Objective To establish the influence of different optical coherence tomography (OCT) biomarkers at baseline treatment on the potential response to anti-vascular endothelial growth factor (VEGF) treatment for diabetic macular oedema (DME). Methods Multicentric, retrospective, case-series study in patients with DME switched to dexamethasone implant injections (DEX-i) after anti-VEGF in real clinical practice. Biomarkers analysed on OCT images at baseline included intraretinal fluid (IRF), subretinal fluid (SRF), disorganisation of retinal inner layers (DRIL), disorganisation of retinal outer layers (DROL), hyperreflective foci (HRF), hyperreflective cystoid walls (HCW), dense intraretinal cyst (DIR) and vitreomacular interface (VMI) abnormalities. DME was classified according to the European School for Advanced Studies in Ophthalmology classification. Patients who were treated with anti-VEGF injections with an adequate response were selected as the control group. Results 275 eyes were analysed in this study; 209 eyes (76.0%) switched from anti-VEGF to DEX-i were compared with 66 control eyes (24.0%). Patients who required switching were statistically older, showed worse initial BCVA and higher CRT. Logistic regression analyses showed that female gender, age, central retinal thickness, type of diabetes, SRF, HCW, DIR and VMI increase the likelihood of switching. The OR regarding the need to switch generated by the presence of two of these three factors (SRF, HCW, VMI) was 48.95. Having all three multiplies it by 4.56×1016. Conclusion If baseline OCT shows two of SRF, HCW and VMI biomarkers at baseline, the risk of failure of anti-VEGF therapy is close to 50%. In the presence at baseline of all three biomarkers, failure of anti-VEGF therapy is almost certain.