A New Ocular Brachytherapy System for the Treatment of Exudative AMD

Abstract

Abstract: : Purpose: To report the positioning techniques and tolerability of the Theragenics Ocular Brachytherapy System (TheraSight System^TM) in the first patients treated for exudative AMD. Methods: The TheraSight System^TM consists of a high dose rate 103 Pd applicator, a sterile sheath, and an articulating arm to stabilize the device after it is inserted into the retrobulbar space and aligned flush with the sclera behind the macula. As part of a multi–center safety and feasibility study, patients with minimally classic or occult AMD lesions are randomized to receive one of three radiation doses (12, 14 or 16 Gy) at a prescription point 2 mm from the face of the device. Patients are evaluated for acute effects at 1, 7 and 30 days, and followed over a 3 year post–treatment interval. Two initial patients with ETDRS vision of 20/200 and 20/400 and active subfoveal occult CNV measuring between 5000 and 6000 microns in GLD were treated with the TheraSight System^TM. Results: After performing a retrobulbar block under conscious sedation, a superotemporal conjunctival peritomy was performed at the limbus. The lateral and superior rectus muscles were looped with silk ties and the device was localized under the macula by indirect ophthalmoscopic visualization of 2 transilluminating lights on the end of the applicator portion of the device. Ultrasonography was used to confirm that the device was positioned flush against the scleral wall. Radiation dose delivery was initiated by retracting a protective lead shield on the end of the device. A third light became visible on the applicator tip to confirm complete retraction of the shield. Proper positioning was confirmed during the dwell time by periodic indirect ophthalmoscopic confirmation of the location of the transilluminating lights. The dwell time was less than 12 minutes and no adjustments in the position were required during this time for either patient. The patients remained comfortable during the procedure and have suffered no adverse events with short post–operative follow–up. Conclusions: The TheraSight Ocular Brachytherapy System^TM can be inserted and positioned effectively and the procedure can be well tolerated. Further evaluation of this brachytherapy system will determine its role in the treatment of exudative AMD.

Keywords: age-related macular degeneration • radiation therapy • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled