Learn More
This paper presents a new supervised method for segmentation of blood vessels in retinal photographs. This method uses an ensemble system of bagged and boosted decision trees and utilizes a feature vector based on the orientation analysis of gradient vector field, morphological transformation, line strength measures, and Gabor filter responses. The feature(More)
Retinal vessel segmentation algorithms are a fundamental component of automatic retinal disease screening systems. This work examines the blood vessel segmentation methodologies in two dimensional retinal images acquired from a fundus camera and a survey of techniques is presented. The aim of this paper is to review, analyze and categorize the retinal(More)
Littmann's formula relating the size of a retinal feature to its measured image size on a telecentric fundus camera film is widely used. It requires only the corneal radius, ametropia, and Littmann's factor q obtained from nomograms or tables. These procedures are here computerized for practitioners' convenience. Basic optical principles are discussed,(More)
BACKGROUND It is uncertain how best to screen pregnant women for the presence of fetal Down's syndrome: to perform first-trimester screening, to perform second-trimester screening, or to use strategies incorporating measurements in both trimesters. METHODS Women with singleton pregnancies underwent first-trimester combined screening (measurement of nuchal(More)
Central visual fields were investigated by automated static perimetry in a group of healthy myopic individuals with peripapillary crescents and tigroid fundus changes only. Results were compared with 'emmetropic' and 'myopic subjects without crescents' control groups. The sample comprised 122 young, healthy volunteers between the ages of 18.5 and 35.4(More)
BACKGROUND UK estimates of age related macular degeneration (AMD) occurrence vary. AIMS To estimate prevalence, number and incidence of AMD by type in the UK population aged ≥50 years. METHODS Age-specific prevalence rates of AMD obtained from a Bayesian meta-analysis of AMD prevalence were applied to UK 2007-2009 population data. Incidence was(More)
PURPOSE To quantify the variation in primary open-angle glaucoma (OAG) prevalence with age, gender, race, year of publication, and survey methodology. METHODS Medline, EMBASE, and PubMed were searched for studies of OAG prevalence. Studies with defined population samplings were sought. Forty-six published observational studies of OAG prevalence (103,567(More)
AIMS To compare methods available to correct the magnification of images that result from the optics of the eye and identify errors, and source of error, of the methods. METHODS 11 methods were applied to ocular biometry data from three independent cohorts. Each method was compared with the method of Bennett, which uses most biometric data. The difference(More)
The change in morphology, diameter, branching pattern or tortuosity of retinal blood vessels is an important indicator of various clinical disorders of the eye and the body. This paper reports an automated method for segmentation of blood vessels in retinal images. A unique combination of techniques for vessel centerlines detection and morphological bit(More)
BACKGROUND Evidence suggests that cluster randomized trials are often poorly designed and analysed. There is little recent research on the methodologic quality of cluster randomized trials and none focuses on primary health care where these trials are increasingly common. METHODS We conducted a systematic review of recent cluster randomized trials in(More)