Increased cup-to-disc ratio Increased vertical cup-to-disc ratio 2018-07-08T00:08:21Z Primary open angle glaucoma is causing a progressive optic neuropathy and its development is associated with loss of tissue in the neuroretinal rim of the optic disc and that will lead to increase in the size of the optic cup. Clinical estimation of the size of the cup using either the slit lamb or a simple imaging modalities such as fundus images is a significant clinical parameter and remains the simplest and most frequently performed assessment of the optic disc in the diagnosis and follows up the progression of the glaucoma suspect. The estimation of the size of the cup is usually made by comparison with the size of the disk and given as the ratio of the vertical and horizontal diameter of the cup to the vertical and horizontal diameter. An abnormal increase in the ratio of the height of the cup of the optic nerve head to the height of the disk.