Automatic Screening and Classification of Diabetic Retinopathy Eye Fundus Image

Diabetic Retinopathy (DR) is a disorder of the retinal vasculature. It develops to some degree in nearly all patients with long-standing diabetes mellitus and can result in blindness. Screening of DR is essential for both early detection and early treatment. This thesis aims to investigate automatic methods for diabetic retinopathy detection and subsequently develop an effective system for the detection and screening of diabetic retinopathy. The presented diabetic retinopathy research involves three development stages. Firstly, the thesis presents the development of a preliminary classification and screening system for diabetic retinopathy using eye fundus images. The research will then focus on the detection of the earliest signs of diabetic retinopathy, which are the microaneurysms. The detection of microaneurysms at an early stage is vital and is the first step in preventing diabetic retinopathy. Finally, the thesis will present decision support systems for the detection of diabetic retinopathy and maculopathy in eye fundus images. The detection of maculopathy, which are yellow lesions near the macula, is essential as it will eventually cause the loss of vision if the affected macula is not treated in time. An accurate retinal screening, therefore, is required to assist the retinal screeners to classify the retinal images effectively. Highly efficient and accurate image processing techniques must thus be used in order to produce an effective screening of diabetic retinopathy. In addition to the proposed diabetic retinopathy detection systems, this thesis will present a new dataset, and will highlight the dataset collection, the expert diagnosis process and the advantages of the new dataset, compared to other public eye fundus images datasets available. The new dataset will be useful to researchers and practitioners working in the retinal imaging area and would widely encourage comparative studies in the field of diabetic retinopathy research. It is envisaged that the proposed decision support system for clinical screening would greatly contribute to and assist the management and the detection of diabetic retinopathy. It is also hoped that the developed automatic detection techniques will assist clinicians to diagnose diabetic retinopathy at an early stage

Automated retinal analysis

Diabetes is a chronic disease affecting over 2% of the population in the UK [1]. Long-term complications of diabetes can affect many different systems of the body including the retina of the eye. In the retina, diabetes can lead to a disease called diabetic retinopathy, one of the leading causes of blindness in the working population of industrialised countries. The risk of visual loss from diabetic retinopathy can be reduced if treatment is given at the onset of sight-threatening retinopathy. To detect early indicators of the disease, the UK National Screening Committee have recommended that diabetic patients should receive annual screening by digital colour fundal photography [2]. Manually grading retinal images is a subjective and costly process requiring highly skilled staff. This thesis describes an automated diagnostic system based oil image processing and neural network techniques, which analyses digital fundus images so that early signs of sight threatening retinopathy can be identified. Within retinal analysis this research has concentrated on the development of four algorithms: optic nerve head segmentation, lesion segmentation, image quality assessment and vessel width measurements. This research amalgamated these four algorithms with two existing techniques to form an integrated diagnostic system. The diagnostic system when used as a 'pre-filtering' tool successfully reduced the number of images requiring human grading by 74.3%: this was achieved by identifying and excluding images without sight threatening maculopathy from manual screening

Cotton Wool Spots in Eye Fundus Scope

Diabetes mellitus é uma doença com um impacto significativo na saúde pública. Trata-se de uma alteração do metabolismo de hidratos de carbono, gorduras e proteínas que são resultado de uma deficiência ou ausência total de secreção/resistência à insulina por parte das células beta do pâncreas. Existem 3 tipos de diabetes, o denominado tipo 1 em que o doente é dependente de insulina, o tipo 2 em que o doente é dependente de insulina e a diabetes gestacional que aparece durante a fase de gravidez. A retinopatia diabética é uma complicação que pode resultar em cegueira. Se for detetada numa fase inicial, pode ser tratada por cirurgia a laser. No entanto, é dificil deteta-la numa fase inicial, uma vez que progride sem sintomas até ocorrer perda de visão de forma irreversível. Assim, se podermos detetar / encontrar exudados algodonosos no fundo de olho utilizando reconhecimento de imagem, anotação automática, sistemas de apoio à decisão de avaliação do risco, conjugados com uma aplicação móvel que permita a aquisição de imagens de fundo de olho, poderemos detetar mais cedo e tratar, evitando o risco cegueira do paciente. Este projeto tem como objetivo desenvolver uma aplicação smartphone baseada em algoritmos de baixo custo, que podem ser altamente eficientes nas imagens de baixa qualidade provenientes da câmara de um smartphone, que pode ser usada como um sistema de apoio à decisão. Este sistema também pode ser extendido a outras doenças oculares, como uma ferramenta útil para o rastreio de saúde ocular nos países em desenvolvimento, reforçar a proximidade dos programas de rastreio para a população. Os principais objetivos são desenvolver sistema fiável de apoio à decisão, considerando exudados algodonosos, juntamente com pontos vermelhos, em vez do sistema actualmente em uso em Portugal, que considera apenas os pontos vermelhos. O número casos Retinopatia Diabética em todo o mundo justifica o desenvolvimento de um sistema de suporte à decisão automatizado para triagem rápida e de baixo custo da Retinopatia Diabética.Diabetes mellitus é uma doença com um impacto significativo na saúde pública. Trata-se de uma alteração do metabolismo de hidratos de carbono, gorduras e proteínas que são resultado de uma deficiência ou ausência total de secreção/resistência à insulina por parte das células beta do pâncreas. Existem 3 tipos de diabetes, o denominado tipo 1 em que o doente é dependente de insulina, o tipo 2 em que o doente é dependente de insulina e a diabetes gestacional que aparece durante a fase de gravidez. A retinopatia diabética é uma complicação que pode resultar em cegueira. Se for detetada numa fase inicial, pode ser tratada por cirurgia a laser. No entanto, é dificil deteta-la numa fase inicial, uma vez que progride sem sintomas até ocorrer perda de visão de forma irreversível. Assim, se podermos detetar / encontrar exudados algodonosos no fundo de olho utilizando reconhecimento de imagem, anotação automática, sistemas de apoio à decisão de avaliação do risco, conjugados com uma aplicação móvel que permita a aquisição de imagens de fundo de olho, poderemos detetar mais cedo e tratar, evitando o risco cegueira do paciente. Este projeto tem como objetivo desenvolver uma aplicação smartphone baseada em algoritmos de baixo custo, que podem ser altamente eficientes nas imagens de baixa qualidade provenientes da câmara de um smartphone, que pode ser usada como um sistema de apoio à decisão. Este sistema também pode ser extendido a outras doenças oculares, como uma ferramenta útil para o rastreio de saúde ocular nos países em desenvolvimento, reforçar a proximidade dos programas de rastreio para a população. Os principais objetivos são desenvolver sistema fiável de apoio à decisão, considerando exudados algodonosos, juntamente com pontos vermelhos, em vez do sistema actualmente em uso em Portugal, que considera apenas os pontos vermelhos. O número casos Retinopatia Diabética em todo o mundo justifica o desenvolvimento de um sistema de suporte à decisão automatizado para triagem rápida e de baixo custo da Retinopatia Diabética.Diabetes mellitus is a disease with significant impact in public health. It is a complex disorder of carbohydrate, fat and protein metabolism that is a result of a deficiency, or complete lack of insulin secretion by the Beta cells of pancreas, or resistance to Insulin. There are 3 types of diabetes, namely type 1 where the patient is insulin-dependent, type 2 where the patient is non insulin-dependent and gestational diabetes that appears during the pregnancy phase.Retinopathy is a diabetes complication that can result in blindness. If detected in an early stage, it can be treated by laser surgery. However its early detection is frequently missed, since it progresses without symptoms until irreversible vision loss occurs.So if we can detect/find cotton wool spots in eye fundus scope by using image recognition, automatic annotation, decision-support systems for risk assessment, conjugate with a mobile app acquiring eye fundus images, we might detect early and treat avoiding patient blindness risk.This project aims to develop a smartphone-based on low computational-cost algorithms, which can be highly efficient in the lower quality images of the smartphone camera, that can be used as a decision-support system. This system may also be extended to other eye diseases, as an useful tool for eye health screening in developing countries and enhance the proximity of screening programs to the population.The main expected contribution is to develop a good decision-support system, considering cotton wool spots, together with red dots, instead of the actual system in use in Portugal which only considers red dots. The number of Diabetic Retinopathy cases worldwide justifies the development of an automated decision-support system for quick and cost effective screening of Diabetic Retinopathy

UNRAVELLING DIABETIC RETINOPATHY THROUGH IMAGE PROCESSING, NEURAL NETWORKS AND FUZZY LOGIC – A REVIEW

One of the main causes of blindness is diabetic retinopathy (DR) and it may affect people of any ages. In these days, both young and old ages are affected by diabetes, and the di abetes is the main cause of DR. Hence, it is necessary to have an automated system with good accuracy and less computation time to diagnose and treat DR, and the automated system can simplify the work of ophthalmologists. The objective is to present an overview of various works recently in detecting and segmenting the various lesions of DR. Papers were categorized based on the diagnosing tools and the methods used for detecting early and advanced stage lesions. The early lesions of DR are microaneurysms, hemorrhages, exudates, and cotton wool spots and in the advanced stage, new and fragile blood vessels can be grown. Results have been evaluated in terms of sensitivity, specificity, accuracy and receiver operating characteristic curve. This paper analyzed the various steps and different algorithms used recently for the detection and classification of DR lesions. A comparison of performances has been made in terms of sensitivity, specificity, area under the curve, and accuracy. Suggestions, future workand the area to be improved were also discussed.Keywords: Diabetic retinopathy, Image processing, Morphological operations, Neural network, Fuzzy logic.Â

Digital ocular fundus imaging: a review

Ocular fundus imaging plays a key role in monitoring the health status of the human eye. Currently, a large number of imaging modalities allow the assessment and/or quantification of ocular changes from a healthy status. This review focuses on the main digital fundus imaging modality, color fundus photography, with a brief overview of complementary techniques, such as fluorescein angiography. While focusing on two-dimensional color fundus photography, the authors address the evolution from nondigital to digital imaging and its impact on diagnosis. They also compare several studies performed along the transitional path of this technology. Retinal image processing and analysis, automated disease detection and identification of the stage of diabetic retinopathy (DR) are addressed as well. The authors emphasize the problems of image segmentation, focusing on the major landmark structures of the ocular fundus: the vascular network, optic disk and the fovea. Several proposed approaches for the automatic detection of signs of disease onset and progression, such as microaneurysms, are surveyed. A thorough comparison is conducted among different studies with regard to the number of eyes/subjects, imaging modality, fundus camera used, field of view and image resolution to identify the large variation in characteristics from one study to another. Similarly, the main features of the proposed classifications and algorithms for the automatic detection of DR are compared, thereby addressing computer-aided diagnosis and computer-aided detection for use in screening programs.Fundação para a Ciência e TecnologiaFEDErPrograma COMPET

A robust lesion boundary segmentation algorithm using level set methods

This paper addresses the issue of accurate lesion segmentation in retinal imagery, using level set methods and a novel stopping mechanism - an elementary features scheme. Specifically, the curve propagation is guided by a gradient map built using a combination of histogram equalization and robust statistics. The stopping mechanism uses elementary features gathered as the curve deforms over time, and then using a lesionness measure, defined herein, ’looks back in time’ to find the point at which the curve best fits the real object. We compare the proposed method against five other segmentation algorithms performed on 50 randomly selected images of exudates with a database of clinician demarcated boundaries as ground truth

Automatic Blood Vessel Extraction of Fundus Images Employing Fuzzy Approach

Diabetic Retinopathy is a retinal vascular disease that is characterized by progressive deterioration of blood vessels in the retina and is distinguished by the appearance of different types of clinical lesions like microaneurysms, hemorrhages, exudates etc. Automated detection of the lesions plays significant role for early diagnosis by enabling medication for the treatment of severe eye diseases preventing visual loss. Extraction of blood vessels can facilitate ophthalmic services by automating computer aided screening of fundus images. This paper presents blood vessel extraction algorithms with ensemble of pre-processing and post-processing steps which enhance the image quality for better analysis of retinal images for automated detection. Extensive performance based evaluation of the proposed approaches is done over four databases on the basis of statistical parameters. Comparison of both blood vessel extraction techniques on different databases reveals that fuzzy based approach gives better results as compared to Kirsch’s based algorithm. The results obtained from this study reveal that 89% average accuracy is offered by the proposed MBVEKA and 98% for proposed BVEFA

Review on Optic Disc Localization Techniques

The optic disc (OD) is one of the important part of the eye for detecting various diseases such as Diabetic Retinopathy and Glaucoma. The localization of optic disc is extremely important for determining hard exudates and lesions. Diagnosis of the disease can prevent people from vision loss. This paper analyzes various techniques which are proposed by different authors for the exact localization of optic disc to prevent vision loss

Development of an automated screening tool for diabetic retinopathy using artificial intelligence

Diabetic retinopathy is the commonest cause of blindness in the working age population in the Western world. It is widely recognised that screening for this treatable condition is highly cost effective. However, there is a shortage in the number of trained personnel required to screen for sight threatening forms of the disease. It has been shown that many of the features of diabetic retinopathy such as microaneurysms, cotton wool spots, exudates and haemorrhages can be identified automatically with high levels of sensitivity and specificity. This work describes the development of an automated computerised system for the screening of diabetic retinopathy through the integration of an artificial intelligent system and the development of custom written software (Diabetic Retinopathy Image Classification Programme) to enable image acquisition, image processing, neural network training and testing to be performed in a structured manner. A combination of conventional image processing and neural network methods are utilised for the identification of the basic features associated with the normal and diabetic fundus image. Preliminary investigations into the identification of sight-threatening features are also described. Identification of normal retinal vasculature and diabetic associated features was performed using three separately trained back-propagtion neural networks. Localisation of the optic disc and macula was achieved by region of interest pixel intensity scanning. Assessment of the optic disc for sight-threatening new vessel growth was performed by comparing the variance in circular intensity profiles of normal optic discs to the variance of those with neovascularisation. Patients were classified as having maculopathy if hard exudates were identified within one disc diameter of the fovea. The overall aim of this project is to develop an automated screening programme for diabetic retinopathy. The initial phase details the development and comparison of a range of algorithms for the detection of features associated with diabetic retinopathy. The final phase details the clinical evaluation of the current screening system

Using shape entropy as a feature to lesion boundary segmentation with level sets

Accurate lesion segmentation in retinal imagery is an area of vast research. Of the many segmentation methods available very few are insensitive to topological changes on noisy surfaces. This paper presents an extension to earlier work on a novel stopping mechanism for level sets. The elementary features scheme (ELS) in [5] is extended to include shape entropy as a feature used to ’look back in time’ and find the point at which the curve best fits the real object. We compare the proposed extension against the original algorithm for timing and accuracy using 50 randomly selected images of exudates with a database of clinician demarcated boundaries as ground truth. While this work is presented applied to medical imagery, it can be used for any application involving the segmentation of bright or dark blobs on noisy images