Tom H. Williamson

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AIM To recognise automatically the main components of the fundus on digital colour images. METHODS The main features of a fundus retinal image were defined as the optic disc, fovea, and blood vessels. Methods are described for their automatic recognition and location. 112 retinal images were preprocessed via adaptive, local, contrast enhancement. The(More)
AIMS The aim was to develop an automated screening system to analyse digital colour retinal images for important features of non-proliferative diabetic retinopathy (NPDR). METHODS High performance pre-processing of the colour images was performed. Previously described automated image analysis systems were used to detect major landmarks of the retinal(More)
AIMS To determine if neural networks can detect diabetic features in fundus images and compare the network against an ophthalmologist screening a set of fundus images. METHODS 147 diabetic and 32 normal images were captured from a fundus camera, stored on computer, and analysed using a back propagation neural network. The network was trained to recognise(More)
OBJECTIVE To determine risk factors for central venous catheter-associated bloodstream infections (CVC-BSI) during a protracted outbreak. DESIGN Case-control and cohort studies of surgical intensive care unit (SICU) patients. SETTING A university-affiliated Veterans Affairs medical center. PATIENTS Case-control study: all patients who developed a(More)
AIMS To develop a system to detect automatically features of diabetic retinopathy in colour digital retinal images and to evaluate its potential in diabetic retinopathy screening. METHODS Macular centred 45 degrees colour retinal images from 1273 patients in an inner city diabetic retinopathy screening programme. A system was used involving pre-processing(More)
Color Doppler ultrasonography has numerous potential applications in the diagnosis and monitoring of many ocular disease processes. One of its advantages over other investigative and diagnostic tests is its safety and repeatability. To be able to fully assess this technique it is important to have good control data and to know the reproducibility of the(More)
BACKGROUND Rhegmatogenous retinal detachments (RRD) with inferior breaks are usually treated by scleral buckling (SB) or pars plana vitrectomy (PPV) or a combination of both methods. However, applying a SB during PPV may produce a risk of choroidal haemorrhage. Following a recent pilot study showing that such cases can be safely treated by PPV without SB(More)
BACKGROUND No substantial recommendations exist regarding the management of anticoagulant drugs prior to ocular surgery. Stopping anticoagulation can cause fatal emboli, but sight-threatening bleeds may occur if anticoagulation is continued. We examined the effects of anticoagulation on vitreoretinal surgery. METHODS Clinical details were prospectively(More)
PURPOSE The purpose of this study was to evaluate the test-retest reproducibility of measures of blood flow velocities using color Doppler imaging (CDI) in orbital arteries. PATIENTS AND METHODS Measures of peak systolic velocity, end-diastolic velocity, and resistive index were performed in a group of 15 normal tension glaucoma patients and in 15 healthy(More)
Color Doppler imaging is a non-invasive ultrasound procedure which permits simultaneous gray scale imaging of structure and color-coded imaging of blood velocity. This improved technique allows the user to identify even very small blood vessels, such as those supplying the eye, from which measures of blood velocity and vascular resistance can be obtained.(More)