Toward Sclera-Force-Based Robotic Assistance for Safe Micromanipulation in Vitreoretinal Surgery

In vitreoretinal surgery instruments are inserted through the sclera to perform precise surgical maneuvers inside the eyeball, which exceeds typical human capabilities. Robotic assistance can enhance the skills of a novice surgeon, provide guidance during tool manipulation based on the desired behavior defined by expert surgeons' maneuvers, and consequently improve the surgical outcome. This paper presents an experimental study characterizing the safe/desired magnitude of forces between the surgical instrument and the sclera insertion port as a function of the tool insertion depth. We explore two types of regressions, a polynomial and a sum of sines fit, to describe the observed user behavior during our one-user pilot study, based on which a variable admittance control scheme can be implemented to robotically guide other users towards this desired behavior for a safe operation.