Publications by authors named "Ceara McGowan"

Article Synopsis
  • Over the past 40 years, around 40,000 Australians have undergone corneal transplants, primarily due to conditions like keratoconus and Fuchs' dystrophy, with increasing demand due to an aging population.
  • The global shortage of donor corneas is significant, with demand exceeding supply by 70 times, particularly in less-developed countries, prompting advancements in tissue banking and surgical techniques.
  • New strategies like organ culture for donor corneas, bespoke surgical methods, and cell culture technologies are improving tissue storage, reducing transplant requirements, and enhancing patient care for corneal conditions.
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Article Synopsis
  • Extraocular electrical stimulation can protect retinal cells but currently relies on patients frequently setting up external electrodes, which is inconvenient.
  • A new minimally-invasive implant has been developed to provide a reliable method for chronic electrical stimulation of the retina, aimed at improving patient adherence to treatment.
  • In a study with adult felines, the device showed surgical and stimulation safety with no adverse effects, stable electrode performance, and no significant changes to retinal health, suggesting it could be a viable long-term solution.
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Objective: Long-term electroencephalogram (EEG) recordings can aid diagnosis and management of various neurological conditions such as epilepsy. In this study we characterize the safety and stability of a clinical grade ring electrode arrays by analyzing EEG recordings, fluoroscopy, and computed tomography (CT) imaging with long-term implantation and histopathological tissue response.

Approach: Seven animals were chronically implanted with EEG recording array consisting of four electrode contacts.

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Purpose: Artificial intelligence (AI) techniques are increasingly being used to classify retinal diseases. In this study we investigated the ability of a convolutional neural network (CNN) in categorizing histological images into different classes of retinal degeneration.

Methods: Images were obtained from a chemically induced feline model of monocular retinal dystrophy and split into training and testing sets.

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Objective: Due to their increased proximity to retinal ganglion cells (RGCs), epiretinal visual prostheses present the opportunity for eliciting phosphenes with low thresholds through direct RGC activation. This study characterised the in vivo performance of a novel prototype monolithic epiretinal prosthesis, containing Nitrogen incorporated ultrananocrystalline (N-UNCD) diamond electrodes.

Approach: A prototype implant containing up to twenty-five 120 × 120 µm N-UNCD electrodes was implanted into 16 anaesthetised cats and attached to the retina either using a single tack or via magnetic coupling with a suprachoroidally placed magnet.

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Purpose: Following successful clinical outcomes of the prototype suprachoroidal retinal prosthesis, Bionic Vision Australia has developed an upgraded 44-channel suprachoroidal retinal prosthesis to provide a wider field of view and more phosphenes. The aim was to evaluate the preclinical passive safety characteristics of the upgraded electrode array.

Methods: Ten normal-sighted felines were unilaterally implanted with an array containing platinum electrodes (44 stimulating and 2 returns) on a silicone carrier near the area centralis.

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Successful visual prostheses require stable, long-term attachment. Epiretinal prostheses, in particular, require attachment methods to fix the prosthesis onto the retina. The most common method is fixation with a retinal tack; however, tacks cause retinal trauma, and surgical proficiency is important to ensure optimal placement of the prosthesis near the macula.

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As the field of biomedical implants matures the functionality of implants is rapidly increasing. In the field of neural prostheses this is particularly apparent as researchers strive to build devices that interact with highly complex neural systems such as vision, hearing, touch and movement. A retinal implant, for example, is a highly complex device and the surgery, training and rehabilitation requirements involved in deploying such devices are extensive.

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Retinal prostheses for the treatment of certain forms of blindness are gaining traction in clinical trials around the world with commercial devices currently entering the market. In order to evaluate the safety of these devices, in preclinical studies, reliable techniques are needed. However, the hard metal components utilised in some retinal implants are not compatible with traditional histological processes, particularly in consideration for the delicate nature of the surrounding tissue.

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Recently, there has been interest in investigating diamond as a material for use in biomedical implants. Diamond can be rendered electrically conducting by doping with boron or nitrogen. This has led to inclusion of boron doped and nitrogen included diamond elements as electrodes and/or feedthroughs for medical implants.

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Purpose: To assess the safety and efficacy of chronic electrical stimulation of the retina with a suprachoroidal visual prosthesis.

Methods: Seven normally-sighted feline subjects were implanted for 96-143 days with a suprachoroidal electrode array and six were chronically stimulated for 70-105 days at levels that activated the visual cortex. Charge balanced, biphasic, current pulses were delivered to platinum electrodes in a monopolar stimulation mode.

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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.

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With the recent development of retinal prostheses, it is important to develop reliable techniques for assessing the safety of these devices in preclinical studies. However, the standard fixation, preparation, and automated histology procedures are not ideal. Here we describe new procedures for evaluating the health of the retina directly adjacent to an implant.

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Purpose: The safety of chronic implantation of a retinal prosthesis in the suprachoroidal space has not been established. This study aimed to determine the safety of a wide-field suprachoroidal electrode array following chronic implantation using histopathologic techniques and electroretinography.

Methods: A platinum electrode array in a wide silicone substrate was implanted unilaterally in the suprachoroidal space in adult cats (n = 7).

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