Displacement of the optic nerve head. Response to acute intraocular pressure elevation in primate eyes
N. S. Levy, E. E. Crapps and R. C. Bonney
Mechanical compression of axons within the lamina scleralis has been
suggested as a mechanism of damage in glaucoma. Movement within the optic
nerve head was studied after acute intraocular pressure elevation in the
enucleated primate eye. Fine platinum wire was positioned with the lamina
scleralis and displacement characterized after IOP elevation. These studies
demonstrate the following: (1) retrodisplacement increases significantly
with increasing pressure, (2) maximum retrodisplacement occurs at the
center and minimum retrodisplacement occurs at the periphery of the optic
nerve, (3) retrodisplacement at the position of minimum movement in the
optic nerve is indistinguishable from that in the sclera, (4) 67% of the
net retrodisplacement occurs after a 15-mm Hg increase in IOP, and (5)
tangential displacements within the lamina scleralis also increase with
increasing pressure but are only 50% of the magnitude of
retrodisplacements.
