EPISCLERAL DEVICES

A minimally invasive retrobulbar episcleral brachytherapy device (SalutarisMD™, Salutaris Medical Devices) has shown promise in the treatment of a small cohort of exudative AMD patients, according to Kamaljit Balaggan MRCOphth, PhD. Dr Balaggan, Moorfields Eye Hospital, London and Department of Genetics at the University College London Institute of Ophthalmology, reported the feasibility and tolerability of the SalutarisMD investigational treatment for wet AMD using a single dose of episcleral brachytherapy in conjunction with intraocular anti-VEGF injections.

“The objectives of the study, carried out at the University of Arizona by Reid Schindler and Leonard Joffe, were achieved in terms of safety and efficacy in a small set of six patients. The device was adequately placed over the macula and the radiation dose was delivered with minimal patient discomfort. The total procedure time is about 15 minutes and there were no serious adverse events,” he told delegates attending the 13th EURETINA Congress in Hamburg.

After two years' follow-up, three out of the four treatment naive patients and one of the chronically treated patients maintained their best-corrected visual acuity levels. Of these, two treatment naive patients did not require any further injections beyond the initial mandated injections. Two patients did, however, deteriorate, noted Dr Balaggan. “One was treatment naive who had an early disciform lesion at the time of enrolment and this matured to a disciform scar within the first year and therefore received no further injections. The other patient was also quite advanced at enrolment and developed a submacular haemorrhage after 11 months and therefore received no further injections. But generally at two years all patients had reduced macular thickness and there were no other adverse events in terms of radiation-related retinopathy,” he said.

Dr Balaggan said that the brachytherapy device potentially allows the radiation dose to be targeted to the treatment zone in a precise, controlled and customised manner for each patient. “There is a strong rationale for using therapeutic radiation in exudative AMD. Radiotherapy is potentially advantageous in that it has anti-angiogenic, anti-inflammatory and anti-fibrotic properties,” he said. The brachytherapy device is designed to be used as a one-off, adjunctive treatment to anti-VEGF injections, said Dr Balaggan. “Combining this therapy with anti- VEGF injections may result in synergy and a reduced anti-VEGF treatment burden for the patients, as well as hopefully increasing the proportion of patients that respond to treatment. It may also enhance the potential of patients to preserve their visual acuity,” he said.

Minimally invasive procedure

One of the advantages of the episcleral device is that it offers a minimally invasive procedure performed under sub-tenon’s anaesthesia and remains episcleral at all times, said Dr Balaggan. The device consists of a curved cannula with a fibre-optic light source at the tip which is attached to a plastic housing in which radioactive strontium-90 seeds, are stored. The seeds are attached to a flexible cable which is, in turn, attached to a plunger. Using an indirect ophthalmoscope, the surgeon guides the probe tip to the CNV area and then depresses the plunger in order to deliver the radioactive seeds to the tip for the treatment duration of around five minutes.

As well as being minimally invasive, the surgeon can target AMD lesions irrespective of their lesion centre, said Dr Balaggan. “By measuring scleral and choroidal thicknesses non-invasively in patients we can also customise the dosing for each patient. It is also important to note that the highest dose is received by the sclera, not the retina and the episcleral probe remains in firm contact with the macula throughout the entire period and this is an inherently stable position,” he said. Summing up, Dr Balaggan said that this initial prospective study supports the safety and tolerability of this novel device, and further evaluation is planned in larger phase I/II trials in 2014.