Quantitative assessments of cup-to-disk ratios in spectral domain optical coherence tomography images for glaucoma diagnosis

Glaucoma, a leading cause of blindness, can change the optic disk and cup significantly. Therefore, the calculation of cup-to-disk ratios is important for glaucoma diagnosis. Currently, most of techniques are only applicable for digital fundus images, not spectral domain optical coherence tomography (SDOCT) images. In this paper, we propose an automatic method to calculate the cup-to-disk ratio in OCT images. The two breakpoints of the retinal pigment epithelium (RPE) layer are firstly detected by combining corresponding binary and flattening images, following the inner limiting membrane (ILM) layer segmentation according to the intensity difference between background and retinal layers. Then, the cup-to-disk ratio can be calculated according to the relevant definition. Experiments demonstrate that the proposed method is effective to a certain degree in quantitative assessments of cup-to-disk ratios.