Design of a Mobile Application for Eye Signs Screening

Mestrado em Engenharia Computação e Instrumentação MédicaAdvances in technology make mobile phones very attractive to everyone, specially smartphones, with a large number of applications, being the medical ones a growing market. In the field of ophthalmology, some diseases or other health problems are being detected very frequently just by looking to a photograph, specially in social networks. This fact encouraged us to create a mobile application that may detect some eye pathologies and that could be used almost by everybody, even in low income countries. In this master thesis the necessary features of a mobile application for eye signs screening are described, portraying some ocular pathologies (amblyopia and retinoblastoma e.g.) that can be detected with a photograph using solely a smartphone with ash. Also the data collection protocol necessary to obtain this data and later process it with the use of algorithms are depicted. A beta version of the developed application is presented, with the set of instructions to the user. This application, to apply the defined protocol, was designed keeping in mind the target user, the parents, who can use it at home as a tool to trace the visual health of their children, given that an ophthalmologist follow-up is scarce or nonexistent in many places. Finally, some results of a Hospital field study are portrayed with complementary medical opinions about the application and also about the protocol designed, which is assessed as a necessary complement to an early diagnosis for important diseases like amblyopia or strabismus that have large incidence in children

Eye tracking in optometry: A systematic review

This systematic review examines the use of eye-tracking devices in optometry, describing their main characteristics, areas of application and metrics used. Using the PRISMA method, a systematic search was performed of three databases. The search strategy identified 141 reports relevant to this topic, indicating the exponential growth over the past ten years of the use of eye trackers in optometry. Eye-tracking technology was applied in at least 12 areas of the field of optometry and rehabilitation, the main ones being optometric device technology, and the assessment, treatment, and analysis of ocular disorders. The main devices reported on were infrared light-based and had an image capture frequency of 60 Hz to 2000 Hz. The main metrics mentioned were fixations, saccadic movements, smooth pursuit, microsaccades, and pupil variables. Study quality was sometimes limited in that incomplete information was provided regarding the devices used, the study design, the methods used, participants' visual function and statistical treatment of data. While there is still a need for more research in this area, eye-tracking devices should be more actively incorporated as a useful tool with both clinical and research applications. This review highlights the robustness this technology offers to obtain objective information about a person's vision in terms of optometry and visual function, with implications for improving visual health services and our understanding of the vision process

Naturalistic depth perception and binocular vision

Humans continuously move both their eyes to redirect their foveae to objects at new depths. To correctly execute these complex combinations of saccades, vergence eye movements and accommodation changes, the visual system makes use of multiple sources of depth information, including binocular disparity and defocus. Furthermore, during development, both fine-tuning of oculomotor control as well as correct eye growth are likely driven by complex interactions between eye movements, accommodation, and the distributions of defocus and depth information across the retina. I have employed photographs of natural scenes taken with a commercial plenoptic camera to examine depth perception while varying perspective, blur and binocular disparity. Using a gaze contingent display with these natural images, I have shown that disparity and peripheral blur interact to modify eye movements and facilitate binocular fusion. By decoupling visual feedback for each eye, I have found it possible to induces both conjugate and disconjugate changes in saccadic adaptation, which helps us understand to what degree the eyes can be individually controlled. To understand the aetiology of myopia, I have developed geometric models of emmetropic and myopic eye shape, from which I have derived psychophysically testable predictions about visual function. I have then tested the myopic against the emmetropic visual system and have found that some aspects of visual function decrease in the periphery at a faster rate in best-corrected myopic observers than in emmetropes. To study the effects of different depth cues on visual development, I have investigated accommodation response and sensitivity to blur in normal and myopic subjects. This body of work furthers our understanding of oculomotor control and 3D perception, has applied implications regarding discomfort in the use of virtual reality, and provides clinically relevant insights regarding the development of refractive error and potential approaches to prevent incorrect emmetropization

Structural Integrity of Eyes Diagnosed with Amblyopia. The measurement of retinal structure in amblyopia using Optical Coherence Tomography.

Amblyopia is the leading cause of monocular visual impairment in children. Therapy for amblyopia is extremely beneficial in some children but ineffective in others. It is critical that the reasons for this discrepancy are understood. Emerging evidence indicates that current clinical protocols for the diagnosis of amblyopia may not be sufficiently sensitive in identifying individuals who, on more detailed examination, exhibit subtle structural defects of the eye. Presently, the magnitude of this problem is unknown. The aim of this study was to establish the prevalence of subtle retinal/optic nerve head defects in eyes diagnosed with amblyopia, to distinguish between possible explanations for the origin of such defects and to investigate the relationship between quantitative measures of retinal structure, retinal nerve fibre layer thickness and optic nerve head dimensions. Using the imaging technique of Optical Coherence Tomography (OCT) retinal structure has been investigated in detail, following the visual pathway across the retina from the fovea, via the paramacular bundle to the optic disc, where peripapillary retinal nerve fibre thickness has been imaged and subjected to detailed measures along with optic disc size and shape. The study formed two phases, the first imaging the eyes of visually normal adults and children, comparing them to amblyopes, both adults and children who had completed their treatment. The second phase, a longitudinal study, investigated retinal structure of amblyopic children undertaking occlusion therapy for the first time. By relating pre-therapy quantitative measures to the visual outcome the second phase of the study aimed to examine whether OCT imaging could identify children achieving a poor final outcome. The results show a clear picture of inter-ocular symmetry structure in all individuals, visually normal and amblyopic. Optic disc characteristics revealed no structural abnormalities in amblyopes, in any of the measured parameters, nor was there any association between the level of visual acuity and the measured structure. At the fovea differences were shown to occur in the presence of amblyopia, with thickening of the fovea and reduction of the foveal pit depth. The structural changes were found to be both bilateral and symmetrical with the fellow eye also affected. In the longitudinal phase of the study these changes were demonstrated to a greater extent in children who ¿failed¿ to respond to treatment. This bilateral, symmetrical structural change found at the fovea, which has not been previously reported, cannot therefore be the primary cause of the visual loss which has been diagnosed as amblyopia

Dialog-driven video-realistic image-based eye animation

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Understanding Education for the Visually Impaired

The contribution that this book makes to scholarship is regarded as ground-breaking, as it is based on recent research conducted with teachers on the ground-level, as well as on research and experiences of practitioners, gained over many years. In this volume, Understanding education for the visually impaired, the focus falls on understanding visual impairment within the South African context, more specifically on what the education of these learners entails. In addition to the contribution to existing literature in the fields of inclusive education and visual impairment, the publication has practical application value for teachers and practitioners who work with and support such learners

Photodynamic Therapy

This book is dedicated to a topic related to the effects of photodynamic therapy organized by Biomedicines in 2022 (https://www.mdpi.com/topics/photodynamic_therapy). In medicine, the use of photodynamic therapy for the treatment of oncological and non-oncological diseases has been widely documented and well codified. In dermatology, the use varies from oncological to the treatment of chronic wounds, as well as in cosmetology for photo-rejuvenation. The 19 manuscripts published in this book cover all aspects of this therapy, including the discovery of new natural and synthetic photosensitizers, biomaterials and nanotechnology, in vitro and in vivo studies, and clinical trials

Understanding Education for the Visually Impaired

The contribution that this book makes to scholarship is regarded as ground-breaking, as it is based on recent research conducted with teachers on the ground-level, as well as on research and experiences of practitioners, gained over many years. In this volume, Understanding education for the visually impaired, the focus falls on understanding visual impairment within the South African context, more specifically on what the education of these learners entails. In addition to the contribution to existing literature in the fields of inclusive education and visual impairment, the publication has practical application value for teachers and practitioners who work with and support such learners

Xenopus

This book focuses on the amphibian, Xenopus, one of the most commonly used model animals in the biological sciences. Over the past 50 years, the use of Xenopus has made possible many fundamental contributions to our knowledge in cell biology, developmental biology, molecular biology, and neurobiology. In recent years, with the completion of the genome sequence of the main two species and the application of genome editing techniques, Xenopus has emerged as a powerful system to study fundamental disease mechanisms and test treatment possibilities. Xenopus has proven an essential vertebrate model system for understanding fundamental cell and developmental biological mechanisms, for applying fundamental knowledge to pathological processes, for deciphering the function of human disease genes, and for understanding genome evolution. Key Features Provides historical context of the contributions of the model system Includes contributions from an international team of leading scholars Presents topics spanning cell biology, developmental biology, genomics, and disease model Describes recent experimental advances Incorporates richly illustrated diagrams and color images Related Titles Green, S. L. The Laboratory Xenopus sp. (ISBN 978-1-4200-9109-0) Faber, J. & P. D. Nieuwkoop. Normal Table of Xenopus laevis (Daudin): A Systematical & Chronological Survey of the Development from the Fertilized Egg till the End of Metamorphosis (ISBN 978-0-8153-1896-5) Jarret, R. L. & K. McCluskey. The Biological Resources of Model Organisms (ISBN 978-1-0320-9095-5