High-Precision Surgical Robotic System for Intraocular Procedures

TL;DR

The paper introduces a high-precision, multi-DOF intraocular robotic system designed to improve tooltip accuracy, tracking, and automated tool exchange for cataract and retina procedures. It combines spherical parallel manipulators with a magnetic lock-and-key tool interface, optimized DH parameters, and OCT-driven calibration to achieve sub-50 µm positioning accuracy and sub-degree orientation control. The approach yields a ~93% reduction in registration error through CT+FK calibration and demonstrates reliable OCT-guided performance including subretinal injections in ex vivo pig eyes with up to 83% success. The work advances robotic ophthalmic surgery by enabling tighter incision control, robust tool exchanges, and micrometer-level manipulation, potentially reducing surgical complications.

Abstract

Despite the extensive demonstration of robotic systems for both cataract and vitreoretinal procedures, existing technologies or mechanisms still possess insufficient accuracy, precision, and degrees of freedom for instrument manipulation or potentially automated tool exchange during surgical procedures. A new robotic system that focuses on improving tooltip accuracy, tracking performance, and smooth instrument exchange mechanism is therefore designed and manufactured. Its tooltip accuracy, precision, and mechanical capability of maintaining small incision through remote center of motion were externally evaluated using an optical coherence tomography (OCT) system. Through robot calibration and precise coordinate registration, the accuracy of tooltip positioning was measured to be 0.053$\pm$0.031 mm, and the overall performance was demonstrated on an OCT-guided automated cataract lens extraction procedure with deep learning-based pre-operative anatomical modeling and real-time supervision.

Figures (13)

• Figure 1: The computer-aided design (CAD) model of the developed robotic system (isometric view) which illustrates the translational stage, two robotic arms, surgical instrument, and tool adapters and holders.
• Figure 2: Shown is the illustration of the robotic arm with joint definition and the robot coordinate frame. All axes of rotation and translation coincide at the RCM. The configuration shown is with $\theta_1=\theta_2=-10^\circ$, $\theta_4=0$, and $d_3=d_5=0$. Arrows indicate the positive direction of each joint.
• Figure 3: Surgical tool interface on the developed robotic arm. The blue area indicates the non-sterilized robotic arm. The green area marks the mechanical coupling between joints 4 and 5 and the tool. The purple circles represent set screws that can align the tooltip $\hat{Z}$ axis with the joint 3 motion.
• Figure 4: Spherical parallel mechanism used for robotic arm optimization. The joint and link definition for the optimization are different from the actual robot design in Fig. \ref{['fig:armAxisDefinition']} and \ref{['fig:roboticArmTool']}.
• Figure 5: Arm optimization result for different angle configurations.