Localization of optic disc in fluorescein angiography images

Optic disc detection is an important task in retinal imaging due to its significance in both clinical and image understanding aspects. In the clinical setting, the optic disc represents the entrance and exit sites of vascular and nervous structures, and its size and shape could be used in diagnostics and treatment of diseases, such as glaucoma. In terms of automated retinal analysis systems, it is used as a landmark point in retinal image registration, the starting point for vessel tracking, and in determining the geometry of the retina. Several approaches have been proposed, the majority of which use intensity - or shape-based techniques. Recently, approaches that combine intensity, shape and information regarding vascular structures have been used with good results. In this paper, a method that combines information from the major blood vessels is investigated and compared with intensity - and shape-based techniques, when used on their own. The image set employed to evaluate the proposed technique consists of both healthy and unhealthy retinas. The techniques discussed in this contribution result to a robust, fast and accurate technique for detection of the optic disc.