Systems for staging the amount of optic nerve damage in glaucoma: a critical review and new material

The evaluation of the appearance of the optic disk is central to the diagnosis and management of patients with glaucoma. Grouping patients into categories, monitoring change, and quantitating the rate of change all require some type of quantitative staging of the amount of damage. Though the scientific literature regarding the appearance of the optic disk in glaucoma is extensive, there is remarkably little about quantitative staging of the amount of damage. We have identified eight systems, including the cup/disk ratio system of Armaly. Most of the earlier systems suffer from a failure to take into account the importance of the size of the optic disk. Furthermore, only one system includes early amounts of damage. This review is a critical appraisal of the known methods for staging optic disk damage in glaucoma, including the recent Disk Damage Likelihood Scale, which appears to offer substantial advantages over the other systems.