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Three-dimensional optical coherence tomography (OCT) is a new ophthalmic imaging technique offering more detailed quantitative analysis of the retinal structure. Eye movement during 3D OCT scanning, however, creates significant spatial distortions that may adversely affect image interpretation and analysis. Current software solutions must use additional reference images or B-scans to correct eye movement...
This paper presents the development of new prismatic actuation approach and its application in human-safe humanoid head design. To reduce actuator output impedance and mitigate unexpected external shock, the prismatic actuation method uses cables to drive a piston with preloaded spring. By leveraging the advantages of parallel manipulator and cable-driven mechanism, the developed neck has a parallel...
Retinal prostheses aim to restore vision to patients who are blind from photoreceptor diseases such as Retinitis Pigmentosa (RP). All implants target the neural cells in the inner retina, the retinal ganglion cells (RGCs). Our research focuses on further understanding the disease process of RP during mid to late stages when total loss of photoreceptors has occurred and significant remodeling of inner...
In order to develop retinal implants with a large number of electrodes, it is necessary to ensure that they do not cause damage to the neural tissue by the heat that the electrical circuits generate. Knowledge about the threshold of the amount of power that induces thermal damage will greatly assist in development of power budgets for implants, which has a significant effect upon the design of implant...
Intrinsic signal optical imaging (ISOI) is a technique that enables researchers to relate changes in cortical activity in response to stimuli by measuring changes in hemoglobin oxygenation and local blood volume. As the time course of these changes - local blood volume in particular - is of the order of seconds, the neural activity that initiates these changes is only indirectly acquired in ISOI....
We use two spatiotemporal Independent Component Analysis algorithms, stJADE and stSOBI, to analyse data from a retinotopic functional magnetic resonance imaging experiment and compare their performance to the analysis of the same data with the spatial ICA done with JADE. This kind of experimental setting has the advantage that the activation in the brain can be estimated fairly easily and therefore...
A continuum network model of the retina is presented, consisting of an active implementation of the retinal ganglion cell tissue layer and passive implementation of deeper cell layers. The retinal ganglion cell layer receives excitatory presynaptic inputs from the bipolar layer and inhibitory presynaptic inputs from the amacrine layer. Simulations were performed to investigate the behavior of retinal...
The Vestibulo-Ocular Reflex (VOR) stabilizes the images of the world on the retinae when the head is in motion. Basic daily activities such as walking or driving depend on the proper functioning of this reflex. For several decades, scientists have developed methods to model and identify this system mathematically. However, traditional methods cannot analyze VOR data comprehensively because they disregard...
Non-invasive optical methods that enable in vivo or in situ visualization of tissue components are of particular relevance in ophthalmology, as they can provide key information about the relationship between the structure and function of the visual system. In this paper we present a semiautomated multimodal imaging tool for co-registration of images of retinal structure and its function, based on...
An indicator of ocular health is the hydrodyanmics of the cornea. Many corneal disorders deteriorate sight as they upset the normal hydrodynamics of the cornea. The mechanisms include the loss of endothelial pump function of corneal dystophies, swelling and immune response of corneal graft rejection, and inflammation and edema, which accompany trauma, burn, and irritation events. Due to high sensitivity...
The cornea is the window of the eye and when it is severely damaged or diseased, vision is impaired. Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK) is a surgical procedure to replace the malfunctioned Descemet's membrane with a healthy one in order to restore the patient's sight. After the operation, ophthalmologists need to monitor the grafted membrane to check for signs of detachment,...
Parkinson's disease (PD) is the second most frequent degenerative disorder after Alzheimer's disease. It is characterized by the depletion of mesenchephalic dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc) and striatal dopamine. Oxidative stress plays a major role in the pathogenesis of Parkinson's disease where DA neurons are especially vulnerable to excessive production of...
Retinal fundus image is an important modality to document the health of the retina and is widely used to diagnose ocular diseases such as glaucoma, diabetic retinopathy and age-related macular degeneration. However, the enormous amount of retinal data obtained nowadays mostly stored locally; and the valuable embedded clinical knowledge is not efficiently exploited. In this paper we present an online...
Most medical images are now digitized and stored in patients files databases. The challenge is how to use them for acquiring knowledge or/and for aid to diagnosis. In this paper, we address the challenge of diagnosis aid by Content Based Image Retrieval (CBIR). We propose to characterize images by using the Bidimensional Empirical Mode Decomposition (BEMD). Images are decomposed into a set of functions...
Automated retinal screening relies on vasculature segmentation before the identification of other anatomical structures of the retina. Vasculature extraction can also be input to image quality ranking, neovascularization detection and image registration. An extensive related literature often excludes the inherent heterogeneity of ophthalmic clinical images. The contribution of this paper consists...
To investigate the flexible adaptation of human visual system, we developed a system to provide different view fields to both eyes of a user respectively. The system named “Virtual Chameleon” consists of two CCD cameras independently controlled and a head-mounted display was used by twelve healthy volunteers. Eleven of them became able to independently control visual axes and understood two different...
This paper presents our experience with developing a portable wireless medical sensor device. We use National Instruments (NI) devices and LabView for measurements studying fatigue of patients suffering multiple sclerosis (MS). Fatigue is a very frequent symptom perceived by MS patients, but the disease mechanism is poorly understood. Many efforts have been made to increase the understanding of this...
Closed/Open angle glaucoma classification is important for glaucoma diagnosis. RetCam is a new imaging modality that captures the image of iridocorneal angle for the classification. However, manual grading and analysis of the RetCam image is subjective and time consuming. In this paper, we propose a system for intelligent analysis of iridocorneal angle images, which can differentiate closed angle...
Age-related macular degeneration (AMD) is a leading cause of blindness worldwide. The disease is highly associated with age, and becoming increasingly prevalent in our aging societies. Drusen is a pathological feature that is well-associated with AMD. In this paper, we present a method of detecting drusen in retinal fundus images. The method first determines the location of the macula, which is used...
In this paper, we investigated the quality of ElectroEncephaloGraphic (EEG) signals during performing physical movements. By using a portable EEG device, the Steady-State Visual Evoked Potential (SSVEP) was recorded on parietal and occipital locations. The SSVEP induced by flickering stimuli was successfully observed in the self-paced mimic walking conditions as well as in the sitting conditions....
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