Axoplasmic flow during chronic experimental glaucoma. 1. Light and electron microscopic studies of the monkey optic nervehead during development of glaucomatous cupping.

The anterior optic nerve and the macular region of the retina of glaucomatous eyes of five rhesus monkeys (Macaca mulatta) have been examined by light and electron microscopy. The experimental glaucoma had been induced by argon laser treatment of the anterior chamber angle. The eyes were examined 3 to 11 weeks after the onset of sustained elevation of intraocular pressure above 20 mm Hg. Severe degenerative changes were seen in eyes with higher intraocular pressure and longer duration of glaucoma. Eyes with a lesser elevation of intraocular pressure and shorter duration of glaucoma showed changes sharply localized to the axon bundles in the scleral lamina cribrosa. Accumulation of mitochondria and dense bodies occurred anterior and posterior to collagenous septae. The location of these changes is in agreement with the localization of block of axoplasmic transport identified by autoradiographic studies. It is speculated that these cytologic changes reflect blockage of axoplasmic flow in the optic nerve of eyes with glaucoma.