title: Detecting abnormality in optic nerve head images using a feature extraction analysis.
abstract: Imaging and evaluation of the optic nerve head (ONH) plays an essential part in the detection and clinical management of glaucoma. The morphological characteristics of ONHs vary greatly from person to person and this variability means it is difficult to quantify them in a standardized way. We developed and evaluated a feature extraction approach using shift-invariant wavelet packet and kernel principal component analysis to quantify the shape features in ONH images acquired by scanning laser ophthalmoscopy (Heidelberg Retina Tomograph [HRT]). The methods were developed and tested on 1996 eyes from three different clinical centers. A shape abnormality score (SAS) was developed from extracted features using a Gaussian process to identify glaucomatous abnormality. SAS can be used as a diagnostic index to quantify the overall likelihood of ONH abnormality. Maps showing areas of likely abnormality within the ONH were also derived. Diagnostic performance of the technique, as estimated by ROC analysis, was significantly better than the classification tools currently used in the HRT software - the technique offers the additional advantage of working with all images and is fully automated.
authors: School of Health Sciences, City University London, London, UK ; National Institute for Health Research Biomedical Research Centre at Moorfields Eye Hospital and University College London Institute of Ophthalmology, UK, London, UK.
authors: Haogang
authors: H
authors: Zhu
authors: Nottingham University Hospitals, Nottingham, UK.
authors: Ali
authors: A
authors: Poostchi
authors: Nottingham University Hospitals, Nottingham, UK ; Department of Ophthalmology, University of Nottingham, Nottingham, UK.
authors: Stephen A
authors: SA
authors: Vernon
authors: School of Health Sciences, City University London, London, UK.
authors: David P
authors: DP
authors: Crabb
keywords: (100.2960) Image analysis; (100.4993) Pattern recognition, Baysian processors; (100.7410) Wavelets; (150.1835) Defect understanding; (170.4470) Ophthalmology; (170.4580) Optical diagnostics for medicine; (170.5755) Retina scanning