Optic disc edema in raised intracranial pressure. III. A pathologic study of experimental papilledema
M. O. Tso and S. S. Hayreh
Optic nerve heads of 21 eyes from 13 rhesus monkeys that had developed
papilledema secondary to chronically raised intracranial pressure from
balloon implantation in the subarachnoid space were studied by light and
electron microscopy. Nine eyes were also examined with the horseradish
peroxidase tracer technique. The pathologic changes in the optic nerve head
included severe axonal changes and mild interstitial edema. Axonal
alteration ranged from axonal swelling to formation of cytoid bodies.
Interstitial edema and vascular leakage of horseradish peroxidase were
noted in the posterior lamina retinalis, lamina choroidalis and lamina
scleralis (prelaminar and lamina cribrosa regions), as well as in the
retrolaminar myelinated optic nerve. No intracellular edema of the glial
elements was noted. Axonal swelling was so prominent that it appeared to be
primarily responsible for the overall swelling of the optic disc observed
ophthalmoscopically.
