Glaucomatous cupping of the human optic disk: a neuro-histologic study.

The optic nerve and optic disk in 20 cases of glaucoma were examined neurohistologically. The interruption of retinal axons was found localized in a narrow transversal strip at the level of the posterior part of the lamina cribrosa and immediately behind it. Retinal axons anterior to this zone were mostly intact as long as their ganglion cells of origin were preserved. This picture was essentially identical in cases of primary and secondary glaucoma. The significance of this finding is discussed together with some hypotheses on the origin and causes of the glaucomatous cupping of the optic disk.