Optic Disk and Optic Cup Segmentation for Glaucoma Screening

Glaucoma is a chronic eye disease that leads to visionless. As it cannot be cured, detecting the disease in time is important. Current tests using intraocular pressure (IOP) are not sensitive enough for population-based glaucoma screening. Optic nerve head assessment in retinal fundus images is both more promising and superior. This paper proposes optic disk and optic cup segmentation using super pixel classification for glaucoma screening. In optic disk segmentation, histograms, and center surround statistics are used to classify each super pixel as disk or non-disk. A self-assessment reliability score is computed to evaluate the quality of the automated optic disk segmentation. For optic cup segmentation, in addition to the histograms and center surround statistics, the location information is also included into the feature space to boost the performance. The proposed segmentation methods have been evaluated in a database of 650 images with optic disk and optic cup boundaries manually marked by trained professionals. Experimental results show an average overlapping error of 9.5 and 24.1 % in optic disk and optic cup segmentation, respectively. The results also show an increase in overlapping error as the reliability score is reduced, which justifies the effectiveness of the self-assessment. The segmented optic disk and optic cup are then used to compute the cup to disk ratio for glaucoma screening. Our proposed method achieves areas under curve of 0.800 and 0.822 in two data sets, which is higher than other methods. The methods can be used for segmentation and glaucoma screening. The self-assessment will be used as an indicator of cases with large errors and enhance the clinical deployment of the automatic segmentation and screening.