ll types of glaucoma involve glaucomatous optic neuropathy. The key to detection and management of glaucoma is understanding how to examine the optic nerve head (ONH). This pictorial glossary addresses the following issues: how to examine the ONH; normal characteristics of the ONH; characteristics of a glaucomatous ONH; how to tell if the glaucomatous optic neuropathy is getting worse;‘pitfalls and pearls’.