Optical Coherence Tomography Guided Robotic Device for Autonomous Needle Insertion in Cornea Transplant Surgery This paper reports the design and evaluation of a novel robotic device for cornea transplant surgery. The device enables the OCTsensor guided Big Bubble hydrodissection approach for deep anterior lamellar keratoplasty (DALK) cornea transplant surgery. DALK is highly challenging because it requires precise placement of a needle into the stroma of the cornea down to Descemets Membrane (DM) and injects a fluid to separate the remaining stroma from Descemetxe2x80x99s membrane. Finally, the stroma is removed and replaced with the donor cornea graft. Compared to traditional penetrating keratoplasty (PK), which involves a fullthickness graft, this method significantly reduces the risk of rejection of the donor cornea by keeping the DM intact. A comparison of autonomous OCT guided needle insertions with expert manual needle insertions showed that the device significantly increased the precision and consistency of the needle placement, which could lead to better visual outcomes and fewer complications. In a study on cadaver porcine eyes, the measured insertion depth as a percentage of cornea thickness for the robotic device was 90.05%  2.33% compared to 79.16%  5.68% for manual insertions.

Towards Realtime Estimation of a Spherical Eye Model based on a Single Fiber OCT Depth perception remains a key challenge in vitreoretinal surgery. Currently users only have the view from an overhead stereomicroscope available, but this means of visualisation is quite restrictive. Optical Coherence Tomography (OCT) has been introduced in the past and is even integrated in a number of commercial systems to provide a more detailed depth vision, even showing subsurface structures up to a few millimeters below the surface. The intraoperative use of OCT, especially in combination with robotics, is still suboptimal. At present one can get either a very slowly updating large volume scan (Cscan) or a faster but not aligned crosssectional Bscan or an even more local single point Ascan at very high update rate. In this work we propose a modelmediated approach. As the posterior eye segment can be approximated as a sphere, we propose to model the retina with this simplified sphere model, the center and radius of which can be estimated in real time. A timevarying Kalman filter is proposed here in combination with an instrumentintegrated optical fiber that provides highfrequency Ascans along the longitudinal instrument direction. The model and convergence of the model has been validated first in a simulation environment and subsequently insilico using an OCT Ascan probe mounted on a comanipulated vitreoretinal robotic system. The probe was manipulated to measure a 3D stereo lithographically printed spherical model of the posterior eye segment. The feasibility of the proposed method was demonstrated in various scenarios. For the insilico validation a 20 micrometer error and convergence speed of 2.0 seconds was found when sampling Ascans at 200Hz.