Force Sensing Augmented Robotic Assistance for Retinal Microsurgery

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Johns Hopkins University
Vitreoretinal surgery, one of the most technically challenging surgical disciplines, treats disorders of the retina, vitreous body, and macula, including retinal detachments, diabetic retinopathy, macular holes, and epiretinal membranes. Fine, precise surgical motion is required to manipulate the delicate eye tissues using small ophthalmic instruments. The forces exerted between ophthalmic tools and eye tissues are often well below human sensory thresholds. The absence of force sensing increases the risk of applying excessive forces on retina tissues, which can potentially cause retinal hemorrhage and tearing. To address these challenges, robotic systems can provide sensing, actuation, and computation that extend natural human capabilities. This dissertation presents the development of novel force sensing tools and robot control methods to provide useful robotic assistance for retinal microsurgery. A typical surgical robot interacts with users (surgeons) and subjects (patients). Quantitative monitoring of these interactions can be enabled through micro force sensing. Two categories of force sensors have been developed: one is the first set of ophthalmic tools that provides intraocular triaxial force sensing at the tool tip, with submillinewton resolution within a submillimeter diameter; the other is the first set of tools that measures forces both at the tool tip and at the sclerotomy site, as well as the location of the sclerotomy along the tool body. Robot control methods based on variable admittance can exploit this force information in order to provide intuitive haptic feedback and natural motion guidance in order to enable safe, efficient robotic assistance for retinal microsurgery. An exemplary robotic endo-illumination system utilizes multi-function force sensing and variable admittance control, demonstrating its potential to resolve the current limitations of bimanual operation and to expand the capabilities of vitreoretinal surgery by enabling further bimanual techniques.
medical robotics, force sensing, variable admittance control, admittance control, impedance control, vitreoretinal surgery