Purpose
Precision in vitreoretinal surgery is a major requirement particularly since the steadiness of the human hand is limited. Recent developments in vitreoretinal surgery such as imaging techniques based on optical coherence tomography allow for micrometer resolution diagnoses. Corresponding surgical precision, however, is not achievable by the human hand. The purpose of this study is to show the applicability of robot assistance in achieving the required precision to enable treatment of manually untreatable levels.
Methods
Human hand tremor is in the order of 100µm when translated to the tip of a vitreoretinal instrument [Riviere, 1997]. The size of the smallest structures that surgeons currently target for treatment is typically in the order of 30µm. To enable surgery for these structures, the surgeon needs assistance. To this end, a high-precision robotic master-slave system has been developed; the PRECEYES Surgical System [Meenink et.al., 2012]. The master-slave layout of the system facilitates motion scaling and tremor filtering, providing a high precision. This precision is validated via reproducibility tests using a laser vibrometer (Polytec OVF-5000 with OVF-552 at 500 µm/V). Furthermore, point-and-pick and cannulation experiments on the chorioallantoic membrane of 12-day fertilized chicken eggs are performed to evaluate the system in practice.
Results
The reproducibility tests show that the robotic system provides an intrinsic precision of 2 to 10µm, depending on the degree of freedom. This precision is calibrated at the tip of the instrument when positioned at the retina, which represents an improvement of 10 to 20 times compared to the human hand. As such, the system enables treatment of manually untreatable levels. This is supported by the cannulation experiments. In these experiments, veins down to 30 µm are penetrated and injected with air using a spiked tip glass micropipette (RI instruments). Besides the high positioning precision, the stand-by functionality of the robotic system allows this position to be held for a long time. Consequently, the injection can be prolonged over several minutes.
Conclusions
A robotic system has been developed to assist the surgeon during vitreoretinal surgery by improving upon human precision with a factor 10 to 20. This high precision allows for the development of procedures / treatment of challenging cases.
Keywords: 762 vitreoretinal surgery •
602 motion-3D