Editor:

We read with special interest the article by Sakuma and associates describing the results of intravitreal autologous plasmin enzyme for macular edema in branch vein occlusion. Our clinical research has focused on the treatment of retinal disorders with autologous plasmin enzyme (APE) for the last 4 years. We have already published the favorable results obtained with APE in the management of diabetic macular edema and vitreomacular traction syndrome. In our research we have also treated cases of macular edema secondary to branch vein occlusion where the vitreous was still attached to the retina, and this seemed to be the cause of the persistence of the edema or its worsening.

We use a simplified and modified technique to obtain the plasmin 45 minutes before the injection compared to the technique used by Sakuma and associates. The concentrations of APE obtained by this simplified method are substantially lower than those obtained by the authors, but they appear to be effective in both inducing posterior vitreous detachment (PVD) and resolving macular edema (the amount of APE obtained with our method was 0.21 IU/0.2 mL on average, measured spectrophotometrically based on the lysis of a chromophoric agent [HD-NVA-CHA-lys-pN]).

At the moment our experience includes 36 patients with a mean follow-up of 12 months. We observed improvement in visual acuity in 80.5% of patients (25) and 88.8% (34) displayed an important decrease in macular thickness after a single injection of APE. The results appeared to persist at least 6 months after only 1 intravitreal injection of APE. Biomicroscopy and optical coherence tomography confirmed a complete posterior detachment in 66.6% of patients (24). We find of interest the fact that both visual acuity and macular thickness improved even in the cases where PVD was not present. These data suggest that APE could work not only as a fibrinolytic agent and have other effects on the eye. No major side effects have been observed during the follow-up of our patients.

We can conclude that APE was effective in the treatment of macular edema associated with branch vein occlusion in our patients, but further studies are needed to confirm its efficacy, actions, and safety.