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226 results on '"Allen, Penelope J"'

2. A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: A Single-Arm Clinical Trial of Feasibility

Author

Blamey, Peter J., Briggs, Robert J., Burns, Owen, Epp, Stephanie B., Johnson, Dean, McDermott, Hugh J., McGowan, Ceara, Millard, Rodney E., Seligman, Peter M., Shepherd, Robert K., Shivdasani, Mohit N., Sinclair, Nicholas C., Thien, Patrick C., Villalobos, Joel, Williams, Chris E., Yeoh, Jonathan, Young, Kiera A., Petoe, Matthew A., Abbott, Carla J., Titchener, Samuel A., Kolic, Maria, Kentler, William G., Nayagam, David A.X., Baglin, Elizabeth K., Kvansakul, Jessica, Barnes, Nick, Walker, Janine G., Karapanos, Lewis, McGuinness, Myra B., Ayton, Lauren N., Luu, Chi D., and Allen, Penelope J.

Published
2025
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6. A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: A Single-Arm Clinical Trial of Feasibility

Author

Petoe, Matthew A., primary, Abbott, Carla J., additional, Titchener, Samuel A., additional, Kolic, Maria, additional, Kentler, William G., additional, Nayagam, David A.X., additional, Baglin, Elizabeth K., additional, Kvansakul, Jessica, additional, Barnes, Nick, additional, Walker, Janine G., additional, Karapanos, Lewis, additional, McGuinness, Myra B., additional, Ayton, Lauren N., additional, Luu, Chi D., additional, Allen, Penelope J., additional, Blamey, Peter J., additional, Briggs, Robert J., additional, Burns, Owen, additional, Epp, Stephanie B., additional, Johnson, Dean, additional, McDermott, Hugh J., additional, McGowan, Ceara, additional, Millard, Rodney E., additional, Seligman, Peter M., additional, Shepherd, Robert K., additional, Shivdasani, Mohit N., additional, Sinclair, Nicholas C., additional, Thien, Patrick C., additional, Villalobos, Joel, additional, Williams, Chris E., additional, Yeoh, Jonathan, additional, and Young, Kiera A., additional

Published
2024
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7. Chronic electrical stimulation with a peripheral suprachoroidal retinal implant: a preclinical safety study of neuroprotective stimulation.

Author

Abbott, Carla J., Allen, Penelope J., Williams, Chris E., Williams, Richard A., Epp, Stephanie B., Burns, Owen, Thomas, Ross, Harrison, Mark, Thien, Patrick C., Saunders, Alexia, McGowan, Ceara, Sloan, Caitlin, Luu, Chi D., and Nayagam, David A. X.

Subjects
ELECTRIC stimulation, FUNDUS oculi, OPTIC nerve diseases, PLATINUM electrodes, RETINAL imaging, OPTICAL coherence tomography, POSTOPERATIVE period, OPHTHALMOSCOPY
Abstract

Purpose: Extraocular electrical stimulation is known to provide neuroprotection for retinal cells in retinal and optic nerve diseases. Currently, the treatment approach requires patients to set up extraocular electrodes and stimulate potentially weekly due to the lack of an implantable stimulation device. Hence, a minimally-invasive implant was developed to provide chronic electrical stimulation to the retina, potentially improving patient compliance for long-term use. The aim of the present study was to determine the surgical and stimulation safety of this novel device designed for neuroprotective stimulation. Methods: Eight normally sighted adult feline subjects were monocularly implanted in the suprachoroidal space in the peripheral retina for 9--39 weeks. Charge balanced, biphasic, current pulses (100 μA, 500 µs pulse width and 50 pulses/s) were delivered continuously to platinum electrodes for 3--34 weeks. Electrode impedances were measured hourly. Retinal structure and function were assessed at 1-, 2-, 4-, 6- and 8-month using electroretinography, optical coherence tomography and fundus photography. Retina and fibrotic thickness were measured from histological sections. Randomized, blinded histopathological assessments of stimulated and non-stimulated retina were performed. Results: All subjects tolerated the surgical and stimulation procedure with no evidence of discomfort or unexpected adverse outcomes. The device position was stable after a post-surgery settling period. Median electrode impedance remained within a consistent range (5-10 kΩ) over time. There was no change in retinal thickness or function relative to baseline and fellow eyes. Fibrotic capsule thickness was equivalent between stimulated and non-stimulated tissue and helps to hold the device in place. Therewas no scarring, insertion trauma, necrosis, retinal damage or fibroblastic response in any retinal samples from implanted eyes, whilst 19% had a minimal histiocytic response, 19% had minimal to mild acute inflammation and 28% had minimal to mild chronic inflammation. Conclusion: Chronic suprathreshold electrical stimulation of the retina using a minimally invasive device evoked a mild tissue response and no adverse clinical findings. Peripheral suprachoroidal electrical stimulation with an implanted device could potentially be an alternative approach to transcorneal electrical stimulation for delivering neuroprotective stimulation. [ABSTRACT FROM AUTHOR]

Published
2024
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14. Estimating Phosphene Locations Using Eye Movements of Suprachoroidal Retinal Prosthesis Users.

Author

Titchener, S.A., Goossens, J., Kvansakul, J., Nayagam, D.A.X., Kolic, M., Baglin, E.K., Ayton, L.N., Abbott, C.J., Luu, C.D., Barnes, N., Kentler, W.G., Shivdasani, M.N., Allen, Penelope J., Petoe, M.A., Titchener, S.A., Goossens, J., Kvansakul, J., Nayagam, D.A.X., Kolic, M., Baglin, E.K., Ayton, L.N., Abbott, C.J., Luu, C.D., Barnes, N., Kentler, W.G., Shivdasani, M.N., Allen, Penelope J., and Petoe, M.A.

Abstract

Item does not contain fulltext, PURPOSE: Accurate mapping of phosphene locations from visual prostheses is vital to encode spatial information. This process may involve the subject pointing to evoked phosphene locations with their finger. Here, we demonstrate phosphene mapping for a retinal implant using eye movements and compare it with retinotopic electrode positions and previous results using conventional finger-based mapping. METHODS: Three suprachoroidal retinal implant recipients (NCT03406416) indicated the spatial position of phosphenes. Electrodes were stimulated individually, and the subjects moved their finger (finger based) or their eyes (gaze based) to the perceived phosphene location. The distortion of the measured phosphene locations from the expected locations (retinotopic electrode locations) was characterized with Procrustes analysis. RESULTS: The finger-based phosphene locations were compressed spatially relative to the expected locations all three subjects, but preserved the general retinotopic arrangement (scale factors ranged from 0.37 to 0.83). In two subjects, the gaze-based phosphene locations were similar to the expected locations (scale factors of 0.72 and 0.99). For the third subject, there was no apparent relationship between gaze-based phosphene locations and electrode locations (scale factor of 0.07). CONCLUSIONS: Gaze-based phosphene mapping was achievable in two of three tested retinal prosthesis subjects and their derived phosphene maps correlated well with the retinotopic electrode layout. A third subject could not produce a coherent gaze-based phosphene map, but this may have revealed that their phosphenes were indistinct spatially. TRANSLATIONAL RELEVANCE: Gaze-based phosphene mapping is a viable alternative to conventional finger-based mapping, but may not be suitable for all subjects.

Published
2023

15. Estimating Phosphene Locations Using Eye Movements of Suprachoroidal Retinal Prosthesis Users

Author

Titchener, Samuel A., primary, Goossens, Jeroen, additional, Kvansakul, Jessica, additional, Nayagam, David A. X., additional, Kolic, Maria, additional, Baglin, Elizabeth K., additional, Ayton, Lauren N., additional, Abbott, Carla J., additional, Luu, Chi D., additional, Barnes, Nick, additional, Kentler, William G., additional, Shivdasani, Mohit N., additional, Allen, Penelope J., additional, and Petoe, Matthew A., additional

Published
2023
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17. Interobserver Agreement of Electrode to Retina Distance Measurements in a Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis

Author

Abbott, Carla J., primary, Baglin, Elizabeth K., additional, Kolic, Maria, additional, McGuinness, Myra B., additional, Titchener, Samuel A., additional, Young, Kiera A., additional, Yeoh, Jonathan, additional, Luu, Chi D., additional, Ayton, Lauren N., additional, Petoe, Matthew A., additional, and Allen, Penelope J., additional

Published
2022
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21. A Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis: Long-Term Observation of the Electrode–Tissue Interface

Author

Titchener, Samuel A., primary, Nayagam, David A. X., additional, Kvansakul, Jessica, additional, Kolic, Maria, additional, Baglin, Elizabeth K., additional, Abbott, Carla J., additional, McGuinness, Myra B., additional, Ayton, Lauren N., additional, Luu, Chi D., additional, Greenstein, Steven, additional, Kentler, William G., additional, Shivdasani, Mohit N., additional, Allen, Penelope J., additional, and Petoe, Matthew A., additional

Published
2022
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23. Development of a Magnetic Attachment Method for Bionic Eye Applications

Author

Fox, Kate, Meffin, Hamish, Burns, Owen, Abbott, Carla J., Allen, Penelope J., Opie, Nicholas L., McGowan, Ceara, Yeoh, Jonathan, Ahnood, Arman, Luu, Chi D., Cicione, Rosemary, Saunders, Alexia L., McPhedran, Michelle, Cardamone, Lisa, Villalobos, Joel, Garrett, David J., Nayagam, David A. X., Apollo, Nicholas V., Ganesan, Kumaravelu, Shivdasani, Mohit N., Stacey, Alastair, Escudie, Mathilde, Lichter, Samantha, Shepherd, Robert K., and Prawer, Steven

Published
2016
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29. Endophthalmitis: Microbiology and Organism Identification Using Current and Emerging Techniques.

Author

Tan, Christine L., Sheorey, Harsha, Allen, Penelope J., and Dawkins, Rosie C. H.

Subjects
ENDOPHTHALMITIS, POLYMERASE chain reaction, NUCLEOTIDE sequencing, MICROBIOLOGY, COMMUNICABLE diseases
Abstract

Endophthalmitis is an ophthalmological emergency requiring timely and appropriate diagnosis and treatment. Microbiological methods of microscopy (Gram's staining) and culture are the current gold standard for organism identification. However, a significant proportion of endophthalmitis remains culture-negative—perhaps the inflammation is non-infectious in origin, results from a novel organism are unidentifiable or because the causative organism is non-culturable often due to pre-treatment with antibiotics. This review outlines the microbiological profile of endophthalmitis, current clinically used methods for organism identification, and the newer molecular techniques of polymerase chain reaction (PCR) and next-generation sequencing (NGS) technology as diagnostic tools for endophthalmitis. They offer the potential to improve organism identification rates and clinical outcomes in infectious diseases, representing an exciting future direction for organism identification in endophthalmitis. Based on the largest ophthalmic hospital in Australia, we highlight the key practical challenges faced by Australian diagnostic laboratories for their use in a clinical setting. [ABSTRACT FROM AUTHOR]

Published
2023
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37. Functional Vision in the Real-World Environment With a Second-Generation (44-Channel) Suprachoroidal Retinal Prosthesis

Author

Karapanos, Lewis, primary, Abbott, Carla J., additional, Ayton, Lauren N., additional, Kolic, Maria, additional, McGuinness, Myra B., additional, Baglin, Elizabeth K., additional, Titchener, Samuel A., additional, Kvansakul, Jessica, additional, Johnson, Dean, additional, Kentler, William G., additional, Barnes, Nick, additional, Nayagam, David A. X., additional, Allen, Penelope J., additional, and Petoe, Matthew A., additional

Published
2021
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40. Oculomotor Responses to Dynamic Stimuli in a 44-Channel Suprachoroidal Retinal Prosthesis

Author

Titchener, Samuel A., primary, Kvansakul, Jessica, additional, Shivdasani, Mohit N., additional, Fallon, James B., additional, Nayagam, D. A. X., additional, Epp, Stephanie B., additional, Williams, Chris E., additional, Barnes, Nick, additional, Kentler, William G., additional, Kolic, Maria, additional, Baglin, Elizabeth K., additional, Ayton, Lauren N., additional, Abbott, Carla J., additional, Luu, Chi D., additional, Allen, Penelope J., additional, and Petoe, Matthew A., additional

Published
2020
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42. In vivo feasibility of epiretinal stimulation using ultrananocrystalline diamond electrodes

Author

Shivdasani, Mohit N, primary, Evans, Mihailo, additional, Burns, Owen, additional, Yeoh, Jonathan, additional, Allen, Penelope J, additional, Nayagam, David A X, additional, Villalobos, Joel, additional, Abbott, Carla J, additional, Luu, Chi D, additional, Opie, Nicholas L, additional, Sabu, Anu, additional, Saunders, Alexia L, additional, McPhedran, Michelle, additional, Cardamone, Lisa, additional, McGowan, Ceara, additional, Maxim, Vanessa, additional, Williams, Richard A, additional, Fox, Kate E, additional, Cicione, Rosemary, additional, Garrett, David J, additional, Ahnood, Arman, additional, Ganesan, Kumaravelu, additional, Meffin, Hamish, additional, Burkitt, Anthony N, additional, Prawer, Steven, additional, Williams, Chris E, additional, and Shepherd, Robert K, additional

Published
2020
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46. A suprachoroidal retinal prosthesis: surgical safety and stability

Author

Allen, Penelope J., Nayagam, D. A. X., Epp, S. B., Luu, C. D., Barnes, N., Kolic, M., Young, K., Baglin, E. K., Abbott, C. J., Briggs, R. J., Yeoh, J., Kentler, W. G., Titchener, S. A., Petoe, M. A., and Williams, C. E.

Subjects
genetic structures, ddc: 610, 610 Medical sciences, Medicine
Abstract

Objective: The success of our prototype clinical trial (NCT01603576) of a suprachoroidal retinal prosthesis led us to develop a second generation fully implantable device, with the aim of providing visual information to profoundly visually impaired patients. Materials and methods: Four patients[for full text, please go to the a.m. URL], Artificial Vision 2019

Published
2019

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