- Biomedical Engineering - Research Publications
Biomedical Engineering - Research Publications
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ItemNo Preview AvailableEstablishing the Calibration Curve of a Compressive Ophthalmodynamometry DeviceKaplan, MA ; Bui, B ; Ayton, LN ; Bao, N ; Grayden, DB ; John, S (IEEE, 2023)The relationship between externally applied force and intraocular pressure was determined using an ex-vivo porcine eye model (N=9). Eyes were indented through the sclera with a convex ophthalmodynamometry head (ODM). Intraocular pressure and ophthalmodynamometric force were simultaneously recorded to establish a calibration curve of this indenter head. A calibration coefficient of 0.140 ± 0.009 mmHg/mN was established and was shown to be highly linear (r = 0.998 ± 0.002). Repeat application of ODM resulted in a 0.010 ± 0.002 mmHg/mN increase to the calibration coefficient.Clinical Relevance- ODM has been highlighted as a potential method of non-invasively estimating intracranial pressure. This study provides relevant data for the practical performance of ODM with similar compressive devices.
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ItemNo Preview AvailableNon-Invasive Measurement of Intracranial Pressure Through Application of Venous Ophthalmodynamometry.Lo, L ; Zhao, D ; Ayton, L ; Grayden, D ; Bui, B ; Morokoff, A ; John, S (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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ItemFirst-in-Human Trial of a Novel Suprachoroidal Retinal ProsthesisAyton, LN ; Blamey, PJ ; Guymer, RH ; Luu, CD ; Nayagam, DAX ; Sinclair, NC ; Shivdasani, MN ; Yeoh, J ; McCombe, MF ; Briggs, RJ ; Opie, NL ; Villalobos, J ; Dimitrov, PN ; Varsamidis, M ; Petoe, MA ; McCarthy, CD ; Walker, JG ; Barnes, N ; Burkitt, AN ; Williams, CE ; Shepherd, RK ; Allen, PJ ; Mori, K (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.