Optic nerve head segmentation in HRT images

Accurate segmentation of the optic nerve head (or optic disk) is very useful during the analysis and assessment of glaucoma in the eye. The Heidelberg Retinal Tomograph (HRT) can acquire high quality images of the optic disk and also allows three dimensional topographic measurements to be made. However, there are significant problems in optic disk segmentation due to having to deal with issues such as distractors along blood vessel edges; the extent of pallor in the optic disk or the very variable appearance of the optic nerve head itself. We propose a multi-scale region and boundary hybrid snake method to extract the optic disk. This model takes account of the vessel edge gradient direction and tries to avoid its force influence when evolving the snake. Experimental results are assessed using an overlap ratio.