Contemporary retinal microsurgery is performed by skilled surgeons through operating microscopes, utilizing free hand techniques and manually operated precision micro-instruments. We have assembled an interdisciplinary team including a clinician scientist and vitreoretinal surgeon, an optical device scientist and a systems integrator to translate existing and developing technology in our laboratories into practical application. To this end we will produce, test in dry and wet models and validate the proposed instrument(s) in vivo. Here we will build upon our previous and ongoing work in fiber optic imaging, sensing and motion detection and control to build a platform for enhancing the surgeon's ability to visualize optically transparent tissues, to identify and track tissue edges, to maintain surgical position, to detect early instrument contact with tissue and to assess depth of tissue penetration. In order to provide these extended capabilities we will incorporate our optical sensor based surface topology, motion limiting and compensation technology into a microsurgery guidance tool that can be placed into the eye. The system will be capable of one-dimensional real-time depth tracking, limitation of tool motion, motion compensation and active surgical targeting and intervention. From initial design the platform will evolve towards a compact and lightweight as well as ergonomically designed tool for free hand use by a micro-surgeon. Three functional surgical tools will be integrated into the visualization and guidance system in order to provide extended surgical capabilities at the site of tool to retina contact. These will include a simple microinjection cannula that will allow assessment of tool tip position, tool-retina contact and depth of retinal penetration as well as to directly deliver therapeutic agents into the retina. The second surgical function will be a surgical blade with tool axis motion and incision depth constrained by surface topology as well as motion limiting and compensation technology utilized for tool guidance. The surgical objective of the tool is to incise the internal limiting membrane with minimal damage to the underlying retina. The strategy for minimizing damage will be to constrain automated cut depth, to limit tool motion and to improve visualization and control of the tool tip relative to the retinal surface. The third surgical tool will be a micro-forceps that will utilize our integrated forward directed common-path optical coherence tomography function in order to assist in identifying visually transparent surgical edges and in tracking surgical progress. Each unique tool application will be quantitatively evaluated using demonstrative dry and wet phantoms in use in our laboratory as well as the ex vivo porcine eye model. At all points in the evaluation process an experienced vitreoretinal surgeon will critically evaluate and propose clinically relevant tool refinements and modifications. Finally, in vivo testing and tool validation, using a rabbit eye model, will be used to advance the technology to a clinical research ready, application.
This proposal addresses fundamental limitations in current vitreoretinal surgery by developing functional free-hand surgical tools that could empower micro-surgeons to achieve surgical objectives, diminish surgical risk and improve outcomes in all microsurgical fields. Further, these capabilities are broadly applicable in other microsurgical problems, and the tools will enable further advances both for ophthalmology and for other microsurgical disciplines.
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