Comparison of intravitreal injection of ranibizumab, steroids, and pars plana vitrectomy for chronic persistent nonimproving diabetic macular edema with nontractional epiretinal membrane

Purpose This study aimed to compare the anatomical and functional outcomes of pars plana vitrectomy (PPV), intravitreal ranibizumab (IVR), and intravitreal triamcinolone acetonide (IVTA) injection in chronic persistent diabetic macular edema (DME) with nontractional epiretinal membrane (NT-ERM). Patients and methods This is a randomized prospective study that included 52 patients having chronic DME with NT-ERM who were divided into three groups: PPV with internal limiting membrane peeling group, IVR group, and IVTA group. The patients were evaluated by optical coherence tomography angiography before and 3 months after the interventions. The primary outcome measures included the changes in best-corrected visual acuity (BCVA) in LogMAR and central subfield foveal thickness (CST), while the secondary outcome measures were changes in intraocular pressure and optical coherence tomography angiography parameters. Results There was no statistically significant change in the BCVA in the PPV group (1.15±0.37 preoperatively to 1.22±0.47 postoperatively, P =0.560). On the other hand, the BCVA significantly improved in the IVR group from 1.04±0.42 preoperatively to 0.725±0.209 postoperatively ( P <0.001) and in the IVTA group from 1.32±0.366 preoperatively to 0.945±0.34 postoperatively ( P <0.001). The intraocular pressure increased significantly in the PPV and in the IVTA groups (from 15±1.65 to 20.33±4.22 mmHg and from 15.4±1.63 to 19.4±2.54 mmHg, respectively, P <0.001). The CST decreased significantly in all groups, with the PPV group showing the greatest reduction from 509.6±129.6 to 380.9±147.5 μm ( P =0.003). The vessel density declined significantly in the PPV group from 40.5±3.5 to 35.9±4.1% ( P <0.001). Conclusion PPV effectively reduced the CST and vessel density but did not improve the visual acuity. Both IVR and IVTA injections provided significant anatomical and functional benefits in chronic DME with NT-ERM.