Abstract
Fundus AutoFluorescence (FAF) images are widely used in the diagnosis and follow-up of Age-related Macular Degeneration, which is the leading cause of blindness in people over 55. There are two kinds of AMD: wet and dry. The most common is the dry form. It is characterized by atrophies of the the retinal pigment epithelium (RPE) with subsequent photoreceptor degeneration. The atrophy severity depends on its size and its location with regard to fovea. The fovea is the macula center, which is the retina central zone (about 2mm. of diameter). The macula has a high density of cone photoreceptors and is not supplied by the retinal capillaries; it receives its blood supply from the choroid. For the determination of the lesions location, we developed an automatic positioning and orientation of a retinal grading grid. Centered on the fovea, it provides information on the spatial distribution of pathologies and thus helps to determine the severity and the danger associated to the detected retinal lesions. This automatic positioning is based on a top down approach, which starts with the vascular tree segmentation and skeletonization. The detected vessels help in localization and detection of the Optic Disc (OD). An approximate OD centre is found by ellipse fitting to the boundary of OD. The vascular tree and the ellipse fitting help in detection of the macula and its center the fovea in relation to the OD center.