A Study on Dual SMART System for Bimanual Microsurgery

Abstract

Manual micro-surgical tasks are fundamentally divided into grasping, cutting and injecting maneuvers performed on biological tissues. Efficient dissection of fibrous tissue from the retina often requires grasping and cutting maneuvers which are carried out simultaneously. True bimanual surgery requires that the surgeon overcomes the hand tremor of both hands at once as well as unpredicted patient’s movement. In this study, we develop and evaluate a dual SMART micro-surgical system for bimanual surgery. The dual SMART system is composed of two common-path swept source optical coherence tomography (CP SS-OCT) distance sensor with a ball lens, two piezoelectric (PZT) motor and customized horizontal scissors and forceps. The ball lens coupled OCT distance sensor could detect the unintended tremor in both hands at tilted angle from 90 to 45 degree. Also, high numerical aperture (NA) of the ball lens coupled OCT sensor has 1.3 times higher signal-to-noise-ratio (SNR) than bare fiber based OCT sensor. In order to achieve efficient bimanual dissection, each end-effector’s desired height could be controlled by the dual SMART system. Total feedback control rate of the system is nearly 500 Hz which is enough to compensate the hand tremor of 6-12 Hz. Additionally, customized horizontal scissors and forceps contribute to accessibility of surgical area compared to commercial vertical scissors and forceps. Results of hand tremor cancellation demonstrate that the ball lens coupled dual SMART system could compensate unpredictable tremor in various tilt angles even in water. The dual SMART system could precisely dissect an egg membrane compared to freehand. The root mean square error (RMSE) of dual SMART is about 10 times smaller than freehand one. Furthermore, dissected surface of the membrane by the system was uniformed. The system with high SNR proved that it could compensate the tremor in a porcine eye compared to freehand. The improved dual SMART system will be useful for bimanual vitrectomy with minimized iatrogenic damage. In the future, durability of the dual SMART system should be improved for the stable microsurgery. ⓒ 2016 DGIST