Changes in Optical Coherence Tomography- Angiography Biomarkers after Treat and Extend Intravitreal Injections of Ranibizumab in Diabetic Macular Edema

Background: Diabetic macular edema (DME) is a leading cause of vision loss in diabetic patients. OCTA provides non-invasive insight into retinal microvascular changes associated with DME. Therefore, this study aims to evaluate changes in OCTA biomarkers following intravitreal ranibizumab using Treat-and-Extend (T&E) protocol and assess their correlation with visual improvement in patients with DME. Methods: This prospective interventional study included 30 treatment-naïve eyes with center-involving DME. All patients received intravitreal ranibizumab injections using T&E regimen. OCTA parameters were assessed at baseline, 3, and 6 months. Results: BCVA substantially improved from 0.8 ± 0.2 to 0.6 ± 0.2 at 3 months and 0.5 at 6 months (P < 0.001). CFT decreased from 500 ± 118 to 364 ± 101 (P < 0.001). Foveal SVD increased, while DVD decreased; FAZ substantially enlarged (P < 0.001). BCVA improvement was negatively correlated with baseline CFT (r = –0.529, P = 0.003) and total SVD (r = –0.512, P = 0.004), and positively correlated with foveal DVD (r = 0.414, P = 0.023). Baseline foveal DVD predicted improvement (AUC = 0.857, P < 0.001; OR = 1.274, P = 0.014), while DRIL was a strong negative predictor (OR = 0.025, P = 0.003). Conclusion: OCTA biomarkers, particularly foveal DVD and DRIL, may serve as reliable predictors of visual outcomes following ranibizumab T&E treatment in DME patients.