Feasibility of Submacular Surgery for Subretinal Delivery of Beta–Radiation Using the Model 2 Neovista Brachytherapy System

Abstract

Abstract: : Purpose: : To evaluate the feasibility and initial safety of submacular surgery for subretinal delivery of beta radiation using the model 2 NeoVista brachytherapy. Methods: Four eyes of 4 dogs underwent pars plana vitrectomy surgery for selective subretinal delivery of beta–radiation using a novel radiation probe, R2.1. The new design resulted in a 1.0mm OD shaft version with a turned down tip (Concorde) which provides adequate CNV/probe distance for treatment positioning. The surgery included vitrectomy, creation of a subretinal bleb using a 41G needle, a retinotomy and introduction of the model 2 brachytherapy probe in the subretinal space. The tip is placed subretinally in gentle contact the RPE while the surgeon’s hand fully supports the weight of the device. The tip remains in soft contact (i.e. contact without pressure) with the RPE for the duration of the procedure. The brachytherapy probe was held in the subretinal space for 3.5 minutes simulating radiation treatment. Following conclusion of the treatment, the surgeon examined the contact point on the RPE, this procedure was repeated for 10 unique treatment sites in each eye. No radiation was delivered in this study. Main outcome measures included the evaluation of the feasibility of the procedure and occurrence of intraoperative complications. Results: Submacular surgery for subretinal delivery of beta–radiation using the model 2 NeoVista brachytherapy system was achieved in all 4 eyes without complications. Throughout the study, there was no subretinal bleeding observed at any of the contact points. Conclusions: Submacular surgery for subretinal delivery of beta–radiation using the NeoVista brachytherapy system using the new designed probe (model 2) is feasible and appears to be safe.

Keywords: radiation therapy • age-related macular degeneration • vitreoretinal surgery