**7. Glaucomatous versus non-glaucomatous damage**

Optic disc cupping is not pathognomonic for the glaucomatous optic neuropathy only [58]. Other diseases such as arteritic ischemic optic neuropathy (AION), optic neuritis, optic disc pit, colobomas, tilted disc, traumatic optic neuropathy, methanol toxicity, compressive lesions of the anterior visual pathways [59], disc drusen, long standing papilledema [26]. However nonglaucomatous disc damage produces optic disc rim pallor while glaucomatous damage produces focal or diffuse obliteration of the neuroretinal rim [60]. Glaucoma damage tends to produce deeper cups than the nonglaucomatous type [61]. In this study open angle glaucoma eyes had larger and deeper cups and smaller neuretinal rims compared to eyes with nonar‐ teritic and arteritic AION. Contrary to glaucoma PPCA does not increase in nonglaucomatous damage [62].

#### **Summary box**

**Figure 13.** Large PPCA in advanced glaucoma with small alpha zone temporally (arrow) and a large beta zone (arrow‐

**Figure 14.** Optic disc haemorrhage in advanced glaucoma. Note the presence of focal arteriolar narrowing (arrow).

head). Bayoneting of the arterioles (white arrowhead)

308 Glaucoma - Basic and Clinical Aspects

There is great variability among healthy subjects and people from different races in the morphology of the optic disc which makes the diagnosis of glaucoma very complicated. The clinician should take into consideration various aspects of the anatomy of the optic nerve head and the RNFL before deciding whether a patient has glaucoma or not
