Disc damage likelihood scale

Glaucoma is a disease characterised by apoptotic ganglion cell death related, at least in part, to intraocular pressure. Any examination for glaucoma must therefore include some comment upon the health of these cells. Unfortunately, it is difficult to examine the ganglion cell layer ophthalmoscopically and so ophthalmologists typically rely on an analysis of a more visible ocular structure—the optic nerve. Ganglion cell death that causes a characteristic optic nerve change—namely, progressive narrowing or loss of the neuroretinal rim, is the hallmark of glaucoma. As scientists and clinicians, ophthalmologists need to both qualitatively and quantitatively describe their ophthalmoscopic impression of the optic nerve both for diagnosis and to establish a baseline so that change may be detected by serial examination. How then should ophthalmologists record their impression of the optic nerve?

Since the late 1960s, the most commonly used quantitative classification of the optic nerve has been Armaly’s cup/disc ratio.¹ This staging scale describes the disc using cup diameter as a percentage of overall disc diameter. The cup/disc ratio, especially the vertical cup/disc ratio, represented a significant advance in quantifying glaucomatous optic neuropathy. Its advantages, namely ease …