Preliminary evaluation of a micro-force sensing handheld robot for vitreoretinal surgery

Highly accurate positioning is fundamental to the performance of vitreoretinal microsurgery. Of vitreoretinal procedures, membrane peeling is among the most prone to complications since extremely delicate manipulation of retinal tissue is required. Associated tool-to-tissue interaction forces are usually below the threshold of human perception, and the surgical tools are moved very slowly, within the 0.1-0.5 mm/s range. During the procedure, unintentional tool motion and excessive forces can easily give rise to vision loss or irreversible damage to the retina. A successful surgery includes two key features: controlled tremor-free tool motion and control of applied force. In this study, we present the potential benefits of a micro-force sensing robot in vitreoretinal surgery. Our main contribution is implementing fiber Bragg grating based force sensing in an active tremor canceling handheld micromanipulator, known as Micron, to measure tool-to-tissue interaction forces in real time. Implemented auditory sensory substitution assists in reducing and limiting forces. In order to test the functionality and performance, the force sensing Micron was evaluated in peeling experiments with adhesive bandages and with the inner shell membrane from chicken eggs. Our findings show that the combination of active tremor canceling together with auditory sensory substitution is the most promising aid that keeps peeling forces below 7 mN with a significant reduction in 2-20 Hz oscillations.