Experimental papilledema produced by cyclocryotherapy.

Cyclocryotherapy was a reliable method of producing prolonged decreased intraocular pressure and papilledema in the rhesus monkey. Histologic changes in papilledema caused by decreased pressure were indistinguishable from those in papilledema from increased intracranial pressure. Electron microscopic observations in papilledema after cyclocryotherapy suggested that the principal morphologic alteration in the optic disk is axonal swelling. Additionally, many mitochondria accumulated in some swollen axons. These changes, observed at the ultrastructural level, suggest that alternations of axoplasmic transport may play a significant role in the pathogenesis of swelling of the disk.