Feasibility of Submacular Surgery for Subretinal Delivery of Beta–radiation

Abstract

Abstract: : Purpose: To evaluate the feasibility and initial safety of submacular surgery for subretinal delivery of beta radiation using a novel NeoVista brachytherapy system. Methods: Ten rabbits underwent pars plana vitrectomy surgery for selective subretinal delivery of beta–radiation using a novel radiation probe. The surgery included vitrectomy, creation of a subretinal bleb using a 30G needle, and introduction of the brachytherapy probe in the subretinal space. The brachytherapy probe was held in the subretinal space for 2 (5 eyes) and 5 (5 eyes) minutes simulating radiation treatment. No radiation was delivered in this study. Neither drainage of the subretinal bleb or laser retinopexy was performed after the procedure. Main outcome measures included changes in the fundus appearance, fluorescein angiography, OCT, ERG and histology (light microscopy). The follow–up period was 1 month. Results:Submacular surgery for subretinal delivery of beta–radiation using the NeoVista Brachytherapy system was achieved in all 10 eyes without complications. The retina was completely reattached at postoperative day 3 and remained attached throughout the follow–up period in all animals. In all animals there were no changes in the fundus appearance, fluorescein angiography, OCT and ERG at 1 month after surgery. No significant changes in the retina, RPE/choriocapillaris/Bruch’s membrane complex, or choroid of the treatment area were seen by light microscopy evaluation after 1 month follow–up when compared to the fellow (non–treated) eye in all 10 animals. Conclusions:Submacular surgery for subretinal delivery of beta–radiation using the NeoVista brachytherapy system is feasible and appears to be safe.

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