Optic nerve grey crescent
- Correspondence to: Dr J B Jonas Universitäts-Augenklinik, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany; Jost.Jonasma.augen.uni-heidelberg.de
Another feature in the morphological assessment of the optic nerve head
The optic nerve head has been defined as all areas inside the peripapillary scleral ring. Outside this ring in the parapapillary region, various features and abnormalities can be differentiated. In almost all eyes, the retinal pigment epithelium shows some histological irregularities close to the tip of Bruch’s membrane at the border of the optic disc. It is the histological equivalent of the alpha zone of parapapillary atrophy which is present in almost all normal eyes. It can usually better be detected at the temporal disc margin than in other parts of the parapapillary region. The beta zone of parapapillary atrophy, present in about 25% of normal eyes, and in a higher percentage of glaucomatous eyes, reflects a complete loss of retinal pigment epithelium cells and an almost complete loss of retinal photoreceptors. Other abnormalities or changes in the parapapillary region include a hypertrophy of the retinal pigment epithelium mainly at the temporal optic disc border in eyes with …
