Towards a clinically applicable robotic assistance system for retinal vein cannulation

Retinal vein cannulation is a promising yet challenging eye surgical procedure currently not practised in clinic. Its goal is to inject a clot-dissolving drug into an occluded retinal vein. Given the scale and the fragility of retinal veins on one side and surgeons' limited positioning precision and force perception on the other side, performing this procedure manually is considered to be too risky. We previously developed a robotic system and a force-sensitive needle to assist surgeons in performing this procedure in a safe manner. In this paper we report on further technological developments and in-lab experiments on the path towards a clinically applicable system. The robotic system is extended with an alignment stage to pre-operatively position it with respect to the patient. It is demonstrated that an alignment accuracy of 0.4 mm can be obtained in less than 20 s. Further, a puncture detection algorithm is proposed for the force-sensitive needle. A 98% detection success rate is shown when cannulating retinal vessels of dissected porcine eyes. Finally, a junior retinal surgeon was invited to perform retinal vein cannulation with the aid of the developed technology on enucleated porcine eyes. The surgeon was able to cannulate and inject a fluid in 20/20 of the times when using the robot and the force-sensitive tool.