Surgery (RMH) - Research Publications
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ItemNo Preview AvailableNon-Invasive Measurement of Intracranial Pressure Through Application of Venous Ophthalmodynamometry.(IEEE, 2021-11)Non-invasive intracranial pressure (ICP) monitoring is possible using venous ophthalmodynamometry to observe a pulsation in retinal blood vessels when intraocular pressure (IOP) exceeds ICP. Here, we identify features in the eye - optic disc and retinal blood vessel locations - and identify pulsation in large retinal blood vessels. The relationship between force and the magnitude of pulsation is used to estimate ICP when force is applied to the eye to gradually increase IOP over time. This approach yields 77% accuracy in automatically observing vessel pulsation.Clinical Relevance - Non-invasive ICP monitoring is desirable to improve patient outcome by reducing potential trauma and complications associated with invasive assessment with intracranial sensors or lumbar puncture.
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ItemDevelopment of a surgical procedure for implantation of a prototype suprachoroidal retinal prosthesis(WILEY, 2014)BACKGROUND: Current surgical techniques for retinal prosthetic implantation require long and complicated surgery, which can increase the risk of complications and adverse outcomes. METHOD: The suprachoroidal position is known to be an easier location to access surgically, and so this study aimed to develop a surgical procedure for implanting a prototype suprachoroidal retinal prosthesis. The array implantation procedure was developed in 14 enucleated eyes. A full-thickness scleral incision was made parallel to the intermuscular septum and superotemporal to the lateral rectus muscle. A pocket was created in the suprachoroidal space, and the moulded electrode array was inserted. The scleral incision was closed and scleral anchor point sutured. In 9 of the 14 eyes examined, the device insertion was obstructed by the posterior ciliary neurovascular bundle. Subsequently, the position of this neurovascular bundle in 10 eyes was characterized. Implantation and lead routing procedure was then developed in six human cadavers. The array was tunnelled forward from behind the pinna to the orbit. Next, a lateral canthotomy was made. Lead fixation was established by creating an orbitotomy drilled in the frontal process of the zygomatic bone. The lateral rectus muscle was detached, and implantation was carried out. Finally, pinna to lateral canthus measurements were taken on 61 patients in order to determine optimal lead length. RESULTS: These results identified potential anatomical obstructions and informed the anatomical fitting of the suprachoroidal retinal prosthesis. CONCLUSION: As a result of this work, a straightforward surgical approach for accurate anatomical suprachoroidal array and lead placement was developed for clinical application.
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ItemFirst-in-Human Trial of a Novel Suprachoroidal Retinal Prosthesis(PUBLIC LIBRARY SCIENCE, 2014-12-18)UNLABELLED: Retinal visual prostheses ("bionic eyes") have the potential to restore vision to blind or profoundly vision-impaired patients. The medical bionic technology used to design, manufacture and implant such prostheses is still in its relative infancy, with various technologies and surgical approaches being evaluated. We hypothesised that a suprachoroidal implant location (between the sclera and choroid of the eye) would provide significant surgical and safety benefits for patients, allowing them to maintain preoperative residual vision as well as gaining prosthetic vision input from the device. This report details the first-in-human Phase 1 trial to investigate the use of retinal implants in the suprachoroidal space in three human subjects with end-stage retinitis pigmentosa. The success of the suprachoroidal surgical approach and its associated safety benefits, coupled with twelve-month post-operative efficacy data, holds promise for the field of vision restoration. TRIAL REGISTRATION: Clinicaltrials.gov NCT01603576.