title: Parapapillary atrophy and optic disc region assessment (PANDORA): retinal imaging tool for assessment of the optic disc and parapapillary atrophy.
abstract: We describe a computer-aided measuring tool, named parapapillary atrophy and optic disc region assessment (PANDORA), for automated detection and quantification of both the parapapillary atrophy (PPA) and the optic disc (OD) regions in two-dimensional color retinal fundus images. The OD region is segmented using a combination of edge detection and ellipse fitting methods. The PPA region is identified by the presence of bright pixels in the temporal zone of the OD, and it is segmented using a sequence of techniques, including a modified Chan-Vese approach, thresholding, scanning filter, and multiseed region growing. PANDORA has been tested with 133 color retinal images (82 with PPA; 51 without PPA) drawn randomly from the Lothian Birth Cohort (LBC) database, together with a "ground truth" estimate from an ophthalmologist. The PPA detection rate is 89.47% with a sensitivity of 0.83 and a specificity of 1. The mean accuracy in defining the OD region is 81.31% (SD=10.45) when PPA is present and 95.32% (SD=4.36) when PPA is absent. The mean accuracy in defining the PPA region is 73.57% (SD=11.62). PANDORA demonstrates for the first time how to quantify the OD and PPA regions using two-dimensional fundus images, enabling ophthalmologists to study ocular diseases related to PPA using a standard fundus camera.
authors.affiliation: School of Engineering, University of Edinburgh, United Kingdom.
authors.forename: Cheng-Kai
authors.initials: CK
authors.lastname: Lu
authors.forename: Tong Boon
authors.initials: TB
authors.lastname: Tang
authors.forename: Augustinus
authors.initials: A
authors.lastname: Laude
authors.forename: Baljean
authors.initials: B
authors.lastname: Dhillon
authors.forename: Alan F
authors.initials: AF
authors.lastname: Murray
mesh_terms: D001284:Atrophy; D016208:Databases, Factual; D003941:Diagnostic Techniques, Ophthalmological; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009898:Optic Disk / Q000473:pathology*; D015203:Reproducibility of Results; D012160:Retina / Q000473:pathology*; D012164:Retinal Diseases / Q000473:pathology; D012984:Software