The document describes a method for glaucoma screening using retinal fundus images. Glaucoma is an irreversible eye disease that can cause vision loss if not detected early. The proposed method uses a novel sparse dissimilarity-constrained coding approach to segment and reconstruct the optic disc from fundus images. Reconstruction coefficients are used to calculate the cup to disc ratio, a metric for detecting glaucoma. The method was tested on 650 images and achieved better accuracy than other methods, with an average error of 0.064 compared to manual measurements. It also achieved good performance in glaucoma screening tests on two datasets. The method shows potential for large-scale population-based glaucoma screening using low-cost retinal imaging.