Robotic Micropuncture With Preload Strategy for Retinal Vein Cannulation

Retinal vein cannulation (RVC) is a surgical procedure utilized in the treatment of retinal vein occlusion. During RVC, the micropuncture process encounters challenges due to unstable contact between the bent needle and the retinal vein, potentially resulting in micropuncture failure. To enhance the success rate, a robotic micropuncture procedure with preload strategy is proposed, which can increase the tissue stiffness and improve stability. First, a nonlinear viscoelastic (NV) model is developed to characterize the nonlinearity and relaxation behavior of the preload force. Subsequently, an NV model based adaptive integral terminal sliding mode controller (NAITSMC) is designed to ensure precise force tracking under tissue uncertainty and respiratory motion. The effectiveness of the robotic micropuncture is validated through in vitro experiments conducted on open-sky porcine eyes. The experimental results indicate that the NV model is more suitable for modeling the force applied to the retinal vein under various inner pressure cases. Under simulated respiratory motion, the NAITSMC demonstrates statistically reduction in error compared to the advanced sliding mode force controller. The preload strategy significantly improves the success rate, achieving a maximum rate of 90%. Furthermore, a preload force of 40 μN is recommended, demonstrating a higher success rate while maintaining acceptable safety considerations.