John A Olson

NHS Health Scotland · Department of Medicine

Introduction Providing systemic screening to a growing diabetes population is a challenge for most screening programmes. We have previously developed software for the automated detection of diabetic retinopathy which is now routinely used within the Scottish Diabetic Retinopathy Screening programme. Purpose In this study we explored whether automa...

Aims: To assess the cost-effectiveness of adopting risk-stratified approaches to extended screening intervals in the national diabetic retinopathy screening programme in Scotland. Methods: A continuous-time hidden Markov model was fitted to national longitudinal screening data to derive transition probabilities between observed non-referable and...

Aim Retinal screening for diabetic retinopathy, involving taking images of the retina, has been shown to be cost-effective. This project explored the feasibility of using automated analysis of sequential retinal images to identify specific features, which could be used to identify those people at risk of their disease progressing and require referr...

Background. Diabetic retinopathy (DR) is an important biomarker for microvascular disease and blindness. Digital fundus photography is a cost-effective way of screening for DR. Access to DR screening is difficult for many South Africans with diabetes. Objective. To perform external quality assurance (EQA) on graders registered in the Ophthalmologi...

Eye is the official journal of the Royal College of Ophthalmologists. It aims to provide the practising ophthalmologist with information on the latest clinical and laboratory-based research.

Retinal screening programmes in England and Scotland have similar photographic grading schemes for background (non-proliferative) and proliferative diabetic retinopathy, but diverge over maculopathy. We looked for the most cost-effective method of identifying diabetic macular oedema from retinal photographs including the role of automated grading a...

Diabetic retinopathy screening aims to detect people at risk of visual loss due to proliferative diabetic retinopathy, but also refers cases of suspected macular oedema (maculopathy). At the introduction of screening, ophthalmology was concerned that referral rates would be unmanageable. We report yield of referable disease by referral reason for t...

Eye is the official journal of the Royal College of Ophthalmologists. It aims to provide the practising ophthalmologist with information on the latest clinical and laboratory-based research.

To determine the best photographic surrogate markers for detecting sight-threatening macular oedema (MO) in people with diabetes attending UK national screening programmes. A multicentre, prospective, observational cohort study of 3170 patients with photographic signs of diabetic retinopathy visible within the macular region [exudates within two di...

Aims/hypothesis The aim of our study was to identify subgroups of patients attending the Scottish Diabetic Retinopathy Screening (DRS) programme who might safely move from annual to two yearly retinopathy screening. Methods This was a retrospective cohort study of screening data from the DRS programme collected between 2005 and 2011 for people age...

Description of outcomes and their ICD-10 codes

Eye is the official journal of the Royal College of Ophthalmologists. It aims to provide the practising ophthalmologist with information on the latest clinical and laboratory-based research.

The aim of this study was to examine the prevalence of and risk factors for diabetic retinopathy in people with newly diagnosed type 2 diabetes mellitus, using Scottish national data. We identified individuals diagnosed with type 2 diabetes mellitus in Scotland between January 2005 and May 2008 using data from the national diabetes database. We cal...

An automated image analysis system for application in mass medical screening must assess the clarity of the images before analysing their content. This is the case in grading for diabetic retinopathy screening where the failure to assess clarity could result in retinal images of people with retinopathy being erroneously classed as normal. This pape...

To develop and evaluate an image grading external quality assurance system for the Scottish Diabetic Retinopathy Screening Programme. A web-based image grading system was developed which closely matches the current Scottish national screening software. Two rounds of external quality assurance were run in autumn 2008 and spring 2010, each time using...

Systematic screening for diabetic retinopathy using retinal photography has been shown to reduce the incidence of blindness among people with diabetes. The implementation of diabetic retinopathy screening programmes faces several challenges. Consequently, methods for improving the efficiency of screening are being sought, one of which is the automa...

Automated grading software has the potential to reduce the manual grading workload within diabetic retinopathy screening programmes. This audit was undertaken at the request of Scotland's National Diabetic Retinopathy Screening Collaborative to assess whether the introduction of automated grading software into the national screening programme would...

Proliferative diabetic retinopathy is a rare condition likely to lead to severe visual impairment. It is characterized by the development of abnormal new retinal vessels. We describe a method for automatically detecting new vessels on the optic disc using retinal photography. Vessel-like candidate segments are first detected using a method based on...

Damage to the optic radiation or the occipital cortex results in loss of vision in the contralateral visual field, termed partial cortical blindness or hemianopia. Previously, we have demonstrated that stimulation in the field defect using visual stimuli with optimal properties for blindsight detection can lead to increases in visual sensitivity wi...

To assess the cost-effectiveness of an improved automated grading algorithm for diabetic retinopathy against a previously described algorithm, and in comparison with manual grading. Efficacy of the alternative algorithms was assessed using a reference graded set of images from three screening centres in Scotland (1253 cases with observable/referabl...

Automated grading has the potential to improve the efficiency of diabetic retinopathy screening services. While disease/no disease grading can be performed using only microaneurysm detection and image-quality assessment, automated recognition of other types of lesions may be advantageous. This study investigated whether inclusion of automated recog...

The Y402H variant of complement factor H (CFH) is associated with risk of age-related macular degeneration (ARMD). In common with ARMD, diabetic retinal disease also appears to involve complement activation. The aim was to investigate the impact of Y402H on both retinal pathologies in patients with Type 2 diabetes (T2DM) undergoing systematic eye s...

Monocular transient visual loss due to emboli or ocular hypoperfusion usually occurs in isolation rather than accompanying a transient neurological deficit.1 Adhiyaman and Adhiyaman did not mention that giant cell arteritis is an important …

OBJECTIVE— To evaluate the performance of a system for automated detection of diabetic retinopathy in digital retinal photographs, built from published algorithms, in a large, representative, screening population. RESEARCH DESIGN AND METHODS— We conducted a retrospective analysis of 10,000 consecutive patient visits, specifically exams (four retina...

Catherine Guly , Graeme Williams , and John Olson take a look at the role of the ophthalmic physician and career opportunities in medical ophthalmology

Automated image analysis is being widely sought to reduce the workload required for grading images resulting from diabetic retinopathy screening programmes. The recognition of exudates in retinal images is an important goal for automated analysis since these are one of the indicators that the disease has progressed to a stage requiring referral to...

National screening programmes for diabetic retinopathy using digital photography and multi-level manual grading systems are currently being implemented in the UK. Here, we assess the cost-effectiveness of replacing first level manual grading in the National Screening Programme in Scotland with an automated system developed to assess image quality a...

To assess the efficacy of automated "disease/no disease" grading for diabetic retinopathy within a systematic screening programme. Anonymised images were obtained from consecutive patients attending a regional primary care based diabetic retinopathy screening programme. A training set of 1067 images was used to develop automated grading algorithms....

Screening programmes for diabetic retinopathy are being introduced in the United Kingdom and elsewhere. These require large numbers of retinal images to be manually graded for the presence of disease. Automation of image grading would have a number of benefits. However, an important prerequisite for automation is the accurate location of the main a...

To identify and quantify the prevalence of patients with uveitis receiving systemic immunosuppression in Scotland. Anonymised data were prospectively collected on all patients with uveitis requiring systemic immunosuppression. Seven health boards participated over a 4-month period between 1 August 2005 and 30 November 2005. 373 patients were identi...

Lesions of the occipital cortex result in areas of cortical blindness affecting the corresponding regions of the patient's visual field. The traditional view is that, aside from some spontaneous recovery in the first few months after the damage, when acute effects have subsided the areas of blindness are absolute and permanent. It has been found, h...

Screening programs using retinal photography for the detection of diabetic eye disease are being introduced in the UK and elsewhere. Automatic grading of the images is being considered by health boards so that the human grading task is reduced. Microaneurysms (MAs) are the earliest sign of this disease and so are very important for classifying whet...

To evaluate the performance of an automated retinal image quality assessment system for use in automated diabetic retinopathy grading. Algorithmic methods have been developed for assessing the quality of 45 degrees single field retinal images for use in diabetic retinopathy screening. For this purpose, image quality was defined by two aspects: imag...

To ascertain the impact of the Health Technology Board for Scotland's grading model on referrals to ophthalmology services. An analysis was performed of the screening outcomes of 5575 consecutive patients, who were screened by the Grampian Diabetic Retinopathy Screening Programme between March and September 2003 according to the recommendations of...

Diabetic retinopathy is the leading cause of blindness in the industrialized world. Hyperglycaemia induces retinal hypoxia that upregulates a range of vasoactive factors which may lead to macular oedema and/or angiogenesis and hence potentially sight threatening retinopathy. In this study, we have focused on the association of CD105 and vascular en...

To report on visual and angiographic outcomes of a consecutive series of patients with inflammatory choroidal neovascular membranes (CNV) unresponsive to systemic immunosuppression treated with photodynamic therapy (PDT). The medical records of six consecutive patients with inflammatory CNVs that failed to respond to systemic immunosuppression and...

An automated system for the measurement of microaneurysm (MA) turnover was developed and compared with manual measurement. The system analyses serial fluorescein angiogram (FA) or red-free (RF) fundus images; fluorescein angiography was used in this study because it is the more sensitive test for MAs. Previous studies have shown that the absolute n...

The Health Technology Board Scotland (HTBS) have issued recommendations for eye screening in patients with diabetes. These are based on evidence-based clinical studies. Evidence-based studies do not answer all the practical issues, and some conclusions have thus been extrapolated from the known evidence base. Other factors such as patient issues, o...

Blindsight is the ability of some cortically blind patients to discriminate visual events presented within their field defect. We have examined a fundamental aspect of visual processing, namely the detection of spatial structures presented within the field defect of 10 cortically blind patients. The method outlined is based on the detection of high...

To compare the respective performances of digital retinal imaging, fundus photography and slit-lamp biomicroscopy performed by trained optometrists, in screening for diabetic retinopathy. To assess the potential contribution of automated digital image analysis to a screening programme. A group of 586 patients recruited from a diabetic clinic underw...

To assess the performance of digital imaging, compared with other modalities, in screening for and monitoring the development of diabetic retinopathy. All imaging was acquired at a hospital assessment clinic. Subsequently, study optometrists examined the patients in their own premises. A subset of patients also had fluorescein angiography performed...

The development of a nationwide eye screening programme for the detection of diabetic retinopathy has generated much interest in automated screening tools. Currently most such systems analyse only intensity information — discarding colour information if it is present. Including colour information in the classifica-tion process is not trivial; large...

Vigabatrin induced constriction of peripheral visual fields was first reported in 1997.1 The potential mechanisms of vigabatrin induced peripheral field constriction are many,2 but in our opinion, not enough attention has been paid to the method and appropriateness of recording this constriction. Current recommendations for patients prescribed viga...

Objective: Guidelines were developed based on best available scientific data as well as consensus of expert opinion in absence of controlled clinical trial data to: 1) assist ophthalmologists with selection of patients for whom photodynamic therapy with verteporfin, termed "verteporfin therapy," should be considered; and 2) offer suggestions regar...

To show true color scanning laser ophthalmoscope (SLO) images produced by simultaneously imaging the retina with red, green, and blue lasers. Low-power red, green, and blue lasers were combined using fiber optics. By rapidly pulsing the lasers, each point on the fundus is illuminated by the 3 colors in quick succession, with the total power level b...

PURPOSE: To determine if photodynamic therapy with verteporfin (Visudyne; Novartis AG, Bulach, Switzerland), termed verteporfin therapy, can safely reduce the risk of vision loss compared with a placebo (with sham treatment) in patients with subfoveal choroidal neovascularization caused by age-related macular degeneration who were identified with a...

Objective: To determine if photodynamic therapy with verteporfin (Visudyne; CIBA Vision Corp, Duluth, GA) can improve the chance of stabilizing or improving vision (<8 letter loss) safely in patients with subfoveal choroidal neovascularization (CNV) caused by pathologic myopia. Design: Multicenter, double-masked, placebo-controlled, randomized clin...

To develop a technique to detect microaneurysms automatically in 50 degrees digital red-free fundus photographs and evaluate its performance as a tool for screening diabetic patients for retinopathy. Candidate microaneurysms are extracted, after the image has been modified to remove variations in background intensity, by algorithms that enhance sma...

Eye is the official journal of the Royal College of Ophthalmologists. It aims to provide the practising ophthalmologist with information on the latest clinical and laboratory-based research.

In the present study, we examined the effect of glucose concentration on the expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta (TGF-beta) mRNA using reverse transcriptase-polymerase chain reaction (RT-betaCR) in normal healthy leukocytes in vitro and in leukocytes fro...

Images of the human retina are routinely used in clinical practice for the diagnosis and management of eye disease. Increased permeability of retinal blood vessels, which is a clinically significant feature, can be visualized with a process known as fluorescein angiography as leakage of fluorescence dye into the surrounding tissues. Analyses of suc...

We compared the performance of three computer based classification methods when applied to the problem of detecting microaneurysms on digitised angiographic images of the retina. An automated image processing system segmented 'candidate' objects (microaneurysms or spurious objects), and produced a list of features on each candidate for use by the c...

Diabetic retinal neovascularisation is considered to be a consequence of retinal ischaemia caused by capillary occlusion. Capillary occlusion is the result of microvascular thrombi in which erythrocytes, platelets and leucocytes each may play a role. We investigated the role of leucocytes in this process and the subsequent angiogenic response. We s...

We have investigated a method of iteratively tracking along blood vessels in a digitised image of the retina, recording information on the morphology of the individual vessels and their macrostructure. Such information may be of use in the detection of vessel changes in diabetes and hypertension, as well as be of use for further image analysis. The...

The symptoms of diabetic retinopathy can be visualised or photographed directly through the pupil using a fundus camera, but the structural changes or lesions are indistinct, too numerous or easily confused with normal retinal features. Our approach to the detection and quantification of the features is based on the classical model of computer visi...

A fully automated digital image processing system, which provides an objective and repeatable way to quantify microaneurysms in digitised fluorescein angiograms, has been developed. The automated computer processing includes registration of same-eye retinal images for serial studies, cutting of regions-of-interest centred on the fovea, the detectio...

A digital image processing system has been developed to quantify and monitor the presence of microaneurysms in retinal fluorescein angiograms. The system is fully automated (except for the initial digitisation), and includes stages for preprocessing, registration of same-eye images obtained at different visits, fovea detection for placement of regi...

Digital image-processing techniques can provide an objective and highly repeatable way of quantifying retinal pathology. This study describes an image-processing strategy which detects and quantifies microaneurysms present in digitized fluorescein angiograms. After preprocessing stages, a bilinear top-hat transformation and matched filtering are em...

Calprotectin, the L1 leucocyte protein, is found in large quantities in the cytosol of granulocytes and monocytes. Plasma calprotectin levels are increased in infections, malignant tumours, vascular insults and various other pathogenic conditions. The authors have investigated plasma calprotectin and ANCA levels in 27 patients with endogenous poste...

Automatic image analysis has much to offer to diabetic retinopathy screening programmes by indefatiga-bly performing disease detection in thousands of retinal photographs. Blot haemorrhages (BH) are one of the signs of diabetic retinopathy and, if present in the macular region or in either hemifield in sufficient number (≥4), are one of the signs t...