NOVEL LASER

Users of a novel navigated 532- nm retinal laser system with integrated imaging (Navilas, OD-OS GmbH, Teltow, Germany) report it is an effective tool for performing panretinal photocoagulation (PRP) to treat high-risk proliferative diabetic retinopathy, and one that appears to have advantages for improving patient comfort as well as treatment efficiency and safety. Ken Lin MD, PhD, and Stephanie Lu MD from the Gavin Herbert Eye Institute at the University of California, Irvine, discussed the laser and their experiences during the 2012 meeting of the Association for Research in Vision and Ophthalmology (ARVO).

They explained that the laser system was designed to treat macular diseases especially diabetic macular oedema in the posterior pole using real-time eye tracking and registration of the diagnostic fluorescein angiography with the treatment plan onto the live fundus imaging. With no need of a contact lens, it offers better comfort to the patient and the physician. Recently, the system has added novel optics to enable PRP treatments in the periphery of the retina. By changing the objective in the optical head and placing a contact lens, the Navilas system enables uniform spot size delivery for PRP. The PRP lens has a 63 x 50 degree static field of view. By moving the joystick laterally and vertically, it is possible to visualise the full posterior pole. There is no need of tilting the lens and therefore astigmatic changes of the image are minimised. As another feature, the platform offers an infrared imaging mode (in addition to live colour fundus imaging, red-free, and fluorescein angiography) that enables greater visibility and PRP in eyes with a mild degree of vitreous haemorrhage.

Dr Lin reported a PRP series comprised of 30 consecutive eyes of 24 patients. Treatment was performed using a 30 ms pulse duration, 300 micron spot size, 253 mW mean power intensity, with 11.5 J applied power, and was delivered to two to four quadrants using a pattern scanning mode. Each eye received an average of 1,532 spots, and eyes treated in all four quadrants received an average of 2,006 spots. Images taken post-treatment demonstrated consistent laser uptake across all quadrants, they reported. When patients who had previously undergone PRP were asked to rate their current experience, they unanimously reported having less pain and greater comfort during the session using the navigated laser. There were no complications during the procedure or the available follow-up. Mean visual acuity was stable from baseline to three months (20/70 and 20/63) as was central macular thickness (279 and 274 microns). Regression of neovascularisation occurred in all eyes by the three-month follow-up. “This system is a smart laser that makes PRP safer, faster and more accurate,†said Dr Lin, noting that to his knowledge, this is the first report of PRP performed with the navigated laser system in a reasonably large series of eyes.

Dr Lu told EuroTimes she has been using the navigated laser for PRP as well as for focal laser treatment for over a year and has been very pleased with her experience. “While the pattern scanning laser (Pascal, Topcon Medical Laser Systems, Inc. Santa Clara, California, USA) also accelerates treatment time for PRP, all of the delivered laser spots using the navigated laser are true focused spots with uniform laser uptake across the quadrants,†said Dr Lu. She added that its benefit for increasing treatment precision and accuracy when performing focal laser photocoagulation for diabetic macular oedema has resulted in a decrease in retreatment rates.