Purpose: To determine whether intravitreal injection of plasmin is effective in treating diffuse diabetic macular edema (DDME).
Design: A prospective, comparative, interventional case study.
Patients: Eighteen patients with bilateral DDME received, as their primary therapeutic treatment, an intravitreal injection of plasmin in one eye, with their contralateral untreated eye serving as a control.
Intervention: Intravitreal 0.2 ml of autologous plasmin injected under topical anesthesia. The plasmin was obtained by a simplified method.
Main outcome measures: Central macular thickness (CMT), determined by optical coherence tomography (OCT), and Best Corrected Visual Acuity (LogMAR), assessed at one and three months of follow-up.
Results: All patients completed the 3-month follow-up assessments. Before the injection, the CMT was 525.22 SD 80.12 microm [mean +/- standard deviation (SD)] in the eyes to be injected, compared to 525.44 SD 78.13 microm in the control eyes. One month after the injection, the CMT was 323.72 SD 44.87 microm in the injected eyes and 518.44 SD 78.54 microm in the control eyes (P < 0.001, bilateral Wilcoxon test for paired samples). Three months after the injection, the CMT was 310.55 SD 35.38 microm in the injected eyes and 517.66 SD 80 microm in the control eyes (P < 0.001). Macular edema improved in all injected eyes (100%), with a reduction of at least 50% in every treated eye, but no changes occurred in the control group. Nine of the 18 treated eyes (50%) improved their BCVA by at least two vision lines. No adverse effects were observed in any of the patients.
Conclusion: Intravitreal plasmin injection, as primary treatment, effectively reduces macular thickening due to DDME and improves visual acuity. Further studies are warranted to assess long-term efficacy and safety.