Advancing the diagnosis of Dry Eye Syndrome : development of dynamic, automated tear film Break-Up assessment

[Resumen] El síndrome de ojo seco es un trastorno común de la película lagrimal que afecta a un sector significativo de la población, impactando en la calidad de vida. El diagnóstico de esta enfermedad es difícil debido a su etiología multifactorial, por lo que hay varias pruebas clínicas para evaluar diferentes aspectos de la película lagrimal. Una de las pruebas empleadas habitualmente es el test de BUT, que consiste en medir el tiempo transcurrido desde el último parpadeo hasta la ruptura de la película lagrimal, representada por la aparición de áreas oscuras que corresponden al adelgazamiento de la película lagrimal en la superficie ocular. Además del tiempo, hay varias características de la ruptura como la zona, la forma, el tamaño y la evolución, que podrían afectar a la severidad del síndrome de ojo seco. Sin embargo, el test de BUT presenta una baja repetibilidad debido principalmente a la apreciación subjetiva de los puntos oscuros, las diferencias entre expertos y la variabilidad de la película lagrimal. Además, la caracterización a mano de las zonas de ruptura es una tarea tediosa que consume mucho tiempo. La automatización del análisis de la ruptura reduciría su carácter subjetivo, permitiendo una evaluación más precisa de la película lagrimal. Este trabajo presenta una metodología novel para una evaluación de la ruptura de la película lagrimal totalmente automática. Este estudio permite un análisis cuantitativo y cualitativo de la inestabilidad de la película lagrimal como una extensi´on de la medida de BUT, que se centra solo en el tiempo. Esta metodolog´ıa proporciona resultados de precisión en los mismos rangos que entre los propios expertos. Así, la evaluación automática de la ruptura ahorra tiempo a los expertos proporcionando resultados imparciales que no están afectados por factores subjetivos.Resumo O síndrome de ollo seco é un trastorno común da película lacrimal que afecta a un sector significativo da poboación, impactando na calidade de vida. A diagnose desta enfermidade é difícil debido a súa etioloxía multifactorial, polo que hai varias probas clínicas para avaliar diferentes aspectos da película lacrimal. Unha das probas empregadas habitualmente é o test de BUT (Break-Up Time), que consiste en medir o tempo transcorrido dende o último pestanexo ata a ruptura da película lacrimal, representada pola aparición de áreas escuras que corresponden ó adelgazamento da película lacrimal na superficie ocular. Ademais do tempo, hai varias características da ruptura como a zona, forma, tamaño e evolución, que poderían afectar á severidade do síndrome de ollo seco. Sen embargo, o test de BUT presenta unha baixa repetibilidade debido principalmente á apreciación subxectiva dos puntos escuros, ás diferencias entre expertos e á variabilidade da película lacrimal. Ademais, a caracterización á man das zonas de ruptura é unha tarefa tediosa que consume moito tempo. A automatización da análise da ruptura reduciría o seu carácter subxectivo, permitindo unha avaliación máis precisa da película lacrimal. Este traballo presenta unha metodoloxía novel para unha avaliación da ruptura da película lacrimal totalmente automática. Este estudo permite unha análise cualitativa e cuantitativa da inestabilidade da película lacrimal como unha extensión da medida de BUT, que se centra só no tempo. Esta metodoloxía proporciona resultados de precisión nos mesmos rangos que entre os propios expertos. Deste xeito, a avaliación automática da ruptura aforra tempo ós expertos proporcionando resultados imparciais que non están afectados por factores subxectivos.[Abstract] Dry Eye Syndrome (DES) is a common disorder of the tear film which affects a significant sector of the population, impacting on quality of life. The diagnosis of this condition is difficult due to its multifactorial etiology, so there are a wide number of tests to evaluate different aspects of the tear film. Among the different tests available, the Break-up Time test (BUT) is a widely used measure to evaluate the quality and stability of the tear film on the ocular surface. It consists in measuring the time elapsed since the last blink until the tear film break-up, that is, the appearance of dark areas related to a thinning of the tear film on the surface of the eye. Besides the time, there are several break-up features such as the location, shape, size and dynamics of the breakup areas, which could affect to dry eye severity. However, the BUT test is affected by low repeatability mainly due to a subjective appreciation of the dark spots, the differences among the experts, and the variability of the tear film. Furthermore, the characterization by hand of break-up areas is a tedious and time consuming task. The automation of the break-up assessment would reduce its subjective character, allowing a more accurate evaluation of tear film stability. This work presents a novel methodology for a fully automatic assessment of the tear film break-up. The proposed methodology allows a quantitative, qualitative analysis of tear film instability, as an extension of BUT measurement, which is focused only on time. It provides accuracy results that are in the same ranges as the experts themselves. Therefore, the automated breakup assessment saves time for experts providing unbiased results which are not affected by subjective factors

A review of miniaturised Non-Destructive Testing technologies for in-situ inspections

Non-destructive testing (NDT) techniques have become attractive trends of product manufacturing, installation and post-maintenance in the aerospace, automotive and manufacturing industry, because of its benefits such as cost saving, easy to use and high efficiency etc. With the industrial products becoming large-scale, high integration and complication, developing the NDT miniaturisation technique for in-situ inspections is highly demanded and becoming an inevitable trend. However, in-situ inspection using NDT have been limited by a number of factors, such as the heavy weight, large size or complex structure etc. This paper aims to systematically identify and analyse the current state-of-the-art of NDT miniaturisation techniques in research and innovation, and discuss the challenge and prospect of miniaturisation of the commonly used NDT techniques

Parallel definition of tear film maps on distributed-memory clusters for the support of dry eye diagnosis

[Abstract] Background and objectives The analysis of the interference patterns on the tear film lipid layer is a useful clinical test to diagnose dry eye syndrome. This task can be automated with a high degree of accuracy by means of the use of tear film maps. However, the time required by the existing applications to generate them prevents a wider acceptance of this method by medical experts. Multithreading has been previously successfully employed by the authors to accelerate the tear film map definition on multicore single-node machines. In this work, we propose a hybrid message-passing and multithreading parallel approach that further accelerates the generation of tear film maps by exploiting the computational capabilities of distributed-memory systems such as multicore clusters and supercomputers. Methods The algorithm for drawing tear film maps is parallelized using Message Passing Interface (MPI) for inter-node communications and the multithreading support available in the C++11 standard for intra-node parallelization. The original algorithm is modified to reduce the communications and increase the scalability. Results The hybrid method has been tested on 32 nodes of an Intel cluster (with two 12-core Haswell 2680v3 processors per node) using 50 representative images. Results show that maximum runtime is reduced from almost two minutes using the previous only-multithreaded approach to less than ten seconds using the hybrid method. Conclusions The hybrid MPI/multithreaded implementation can be used by medical experts to obtain tear film maps in only a few seconds, which will significantly accelerate and facilitate the diagnosis of the dry eye syndrome.Ministerio de Economía y Competitividad; TIN2013-42148-PPortugal. Fundação para a Ciência e a Tecnologia; POCI-01-0145-FEDER-006961Portugal. Fundação para a Ciência e a Tecnologia; UID/EEA/50014/2013Portugal. Fundação para a Ciência e a Tecnologia; SFRH/BPD/111177/2015

Stretchable mould interconnect optimization : peeling automation and carrierless techniques

The primary bottleneck of the stretchable mold interconnect (SMI) technology is its reliance on carrier boards. These are necessary to handle the meandered circuit during production and to ensure dimensional stability of the flexible circuit board before encapsulation. However, for all the problems it solves, it also introduces a new major problem by requiring a peeling step – which is difficult to automate. This manuscript aims to present some of the work that went into eliminating this problem, discussing both unsuccessful and functioning methods to tackle this conundrum and some of the experimental work that went into verifying these techniques. First, alterations to the design to simplify peeling are considered, followed by adhesivebased peeling processes and mechanical pin-based systems. Next, masking and structuring of the carrier board adhesive are considered. Finally, two carrierless methods which circumvent the problems are discussed, a two-step process – which cuts temporary support structures after partial encapsulation – and a technique whereby the frame is designed to fail in a controlled manner during the first use of the circuit, creating a carrierless process feasible for high-volume production

The Development of a Validated Clinically Meaningful Endpoint for the Evaluation of Tear Film Stability as a Measure of Ocular Surface Protection for Use in the Diagnosis and Evaluation of Dry Eye Disease

abstract: This dissertation presents methods for the evaluation of ocular surface protection during natural blink function. The evaluation of ocular surface protection is especially important in the diagnosis of dry eye and the evaluation of dry eye severity in clinical trials. Dry eye is a highly prevalent disease affecting vast numbers (between 11% and 22%) of an aging population. There is only one approved therapy with limited efficacy, which results in a huge unmet need. The reason so few drugs have reached approval is a lack of a recognized therapeutic pathway with reproducible endpoints. While the interplay between blink function and ocular surface protection has long been recognized, all currently used evaluation techniques have addressed blink function in isolation from tear film stability, the gold standard of which is Tear Film Break-Up Time (TFBUT). In the first part of this research a manual technique of calculating ocular surface protection during natural blink function through the use of video analysis is developed and evaluated for it's ability to differentiate between dry eye and normal subjects, the results are compared with that of TFBUT. In the second part of this research the technique is improved in precision and automated through the use of video analysis algorithms. This software, called the OPI 2.0 System, is evaluated for accuracy and precision, and comparisons are made between the OPI 2.0 System and other currently recognized dry eye diagnostic techniques (e.g. TFBUT). In the third part of this research the OPI 2.0 System is deployed for use in the evaluation of subjects before, immediately after and 30 minutes after exposure to a controlled adverse environment (CAE), once again the results are compared and contrasted against commonly used dry eye endpoints. The results demonstrate that the evaluation of ocular surface protection using the OPI 2.0 System offers superior accuracy to the current standard, TFBUT.Dissertation/ThesisPh.D. Industrial Engineering 201

Technological enhancements to optometric clinical tests

A sizeable amount of the testing in eye care, requires either the identification of targets such as letters to assess functional vision, or the subjective evaluation of imagery by an examiner. Computers can render a variety of different targets on their monitors and can be used to store and analyse ophthalmic images. However, existing computing hardware tends to be large, screen resolutions are often too low, and objective assessments of ophthalmic images unreliable. Recent advances in mobile computing hardware and computer-vision systems can be used to enhance clinical testing in optometry. High resolution touch screens embedded in mobile devices, can render targets at a wide variety of distances and can be used to record and respond to patient responses, automating testing methods. This has opened up new opportunities in computerised near vision testing. Equally, new image processing techniques can be used to increase the validity and reliability of objective computer vision systems. Three novel apps for assessing reading speed, contrast sensitivity and amplitude of accommodation were created by the author to demonstrate the potential of mobile computing to enhance clinical measurement. The reading speed app could present sentences effectively, control illumination and automate the testing procedure for reading speed assessment. Meanwhile the contrast sensitivity app made use of a bit stealing technique and swept frequency target, to rapidly assess a patient’s full contrast sensitivity function at both near and far distances. Finally, customised electronic hardware was created and interfaced to an app on a smartphone device to allow free space amplitude of accommodation measurement. A new geometrical model of the tear film and a ray tracing simulation of a Placido disc topographer were produced to provide insights on the effect of tear film breakdown on ophthalmic images. Furthermore, a new computer vision system, that used a novel eye-lash segmentation technique, was created to demonstrate the potential of computer vision systems for the clinical assessment of tear stability. Studies undertaken by the author to assess the validity and repeatability of the novel apps, found that their repeatability was comparable to, or better, than existing clinical methods for reading speed and contrast sensitivity assessment. Furthermore, the apps offered reduced examination times in comparison to their paper based equivalents. The reading speed and amplitude of accommodation apps correlated highly with existing methods of assessment supporting their validity. Their still remains questions over the validity of using a swept frequency sine-wave target to assess patient’s contrast sensitivity functions as no clinical test provides the range of spatial frequencies and contrasts, nor equivalent assessment at distance and near. A validation study of the new computer vision system found that the authors tear metric correlated better with existing subjective measures of tear film stability than those of a competing computer-vision system. However, repeatability was poor in comparison to the subjective measures due to eye lash interference. The new mobile apps, computer vision system, and studies outlined in this thesis provide further insight into the potential of applying mobile and image processing technology to enhance clinical testing by eye care professionals

An Approach to the Procedural Generation of Worn Metal Surfaces

Motivated by the phenomenon that wear and tear tends to happen more near sharp cornersof a surface, this thesis presents a method for procedurally generating photorealistic metal surfacesbased upon evaluating curvature values. The thesis describes the development of eight metal shadersthat are used to replace the manual texture painting typically used in production. The approach isdemonstrated by applying these metal shaders to a robotic dog model from a short film involvinglive action and CG elements. Frames from a short animation of the robotic dog are presented, anda discussion of the strengths and weaknesses of this methodology

Ophthalmic engineering:the development of novel instrumentation to further research in the field

The principle theme of this thesis is the advancement and expansion of ophthalmic research via the collaboration between professional Engineers and professional Optometrists. The aim has been to develop new and novel approaches and solutions to contemporary problems in the field. The work is sub divided into three areas of investigation; 1) High technology systems, 2) Modification of current systems to increase functionality, and 3) Development of smaller more portable and cost effective systems. High Technology Systems: A novel high speed Optical Coherence Tomography (OCT) system with integrated simultaneous high speed photography was developed achieving better operational speed than is currently available commercially. The mechanical design of the system featured a novel 8 axis alignment system. A full set of capture, analysis, and post processing software was developed providing custom analysis systems for ophthalmic OCT imaging, expanding the current capabilities of the technology. A large clinical trial was undertaken to test the dynamics of contact lens edge interaction with the cornea in-vivo. The interaction between lens edge design, lens base curvature, post insertion times and edge positions was investigated. A novel method for correction of optical distortion when assessing lens indentation was also demonstrated. Modification of Current Systems: A commercial autorefractor, the WAM-5500, was modified with the addition of extra hardware and a custom software and firmware solution to produce a system that was capable of measuring dynamic accommodative response to various stimuli in real time. A novel software package to control the data capture process was developed allowing real time monitoring of data by the practitioner, adding considerable functionality of the instrument further to the standard system. The device was used to assess the accommodative response differences between subjects who had worn UV blocking contact lens for 5 years, verses a control group that had not worn UV blocking lenses. While the standard static measurement of accommodation showed no differences between the two groups, it was determined that the UV blocking group did show better accommodative rise and fall times (faster), thus demonstrating the benefits of the modification of this commercially available instrumentation. Portable and Cost effective Systems: A new instrument was developed to expand the capability of the now defunct Keeler Tearscope. A device was developed that provided a similar capability in allowing observation of the reflected mires from the tear film surface, but with the added advantage of being able to record the observations. The device was tested comparatively with the tearscope and other tear film break-up techniques, demonstrating its potential. In Conclusion: This work has successfully demonstrated the advantages of interdisciplinary research between engineering and ophthalmic research has provided new and novel instrumented solutions as well as having added to the sum of scientific understanding in the ophthalmic field

Evaluation of Durability of Nonwoven Polypropylene Grocery Bags Under Routine Use

Recently, the thin plastic-film bags distributed at thousands of checkouts across the United States have been targeted by environmental advocacy groups as wasteful nuisance packaging, and many places have passed legislation to ban or restrict their distribution. The resulting demand for a more durable grocery bag able to withstand reuse has led to a rise in popularity for bags made from fabric, and the relative durability and low cost of nonwoven polypropylene fabric has made it a popular choice of material. However, studies have shown that these bags come with their own set of issues: their reusability makes them a vector for cross-contamination, and many consumers do not reuse their bags enough to recoup the additional cost of materials and energy needed to create the thicker material. Many of the bag laws offer guidelines for determining if a given bag officially qualifies as “reusable,” but at this time, virtually no data exists regarding the real-world durability of nonwoven polypropylene bags. To test whether they could handle the real-world wear-and-tear, 40 nonwoven polypropylene bags were loaded with grocery items and carried by hand for 125 repetitions of 175 feet, with half of the samples undergoing machine-washing every 25 repetitions to determine if washing would affect the durability of the bag. Additionally, 80 bags were tested with the mechanically-assisted ATP-001 testing protocol suggested by the Los Angeles County Department of Public Works, to see if it could serve as an acceptable alternative to the physically-intensive walk test. Half of this sample was also washed, to see if this had an effect on lifespan. All 20 of the unwashed, hand-carried bags withstood at least 50 reuses, and 12 out of 20 of them withstood the required 125 reuses necessary to meet the most strenuous definition of reusable bag required by various municipal laws. Washing did appear to result in a lower lifespan, with only 7 of the 20 bags able to withstand both 125 reuses and 5 machine-wash cycles. The ATP-001 tests, conducted with slightly different criteria for failure, resulted in similar rates of success, with 23 out of 40 unwashed bags and 14 out of 40 washed bags able to withstand testing