The dynamics and location of axonal transport blockade by acute intraocular pressure elevation in primate optic nerve

Axonal transport in primate optic nerve axons was studied by autoradiography, scintillation counting, and electron microscopy under conditions of short-term intraocular pressure elevation. With elevation of intraocular pressure to 30 mm. Hg below mean arterial blood pressure, blockage of transport was detected within 2 hours by autoradiography and within 1 hour by electron microscopy. The earliest buildup of radioactively labeled protein and ultrastructurally visible cellular organelles was within the scleral lamina cribrosa. The degree of blockage, judged by amount of label buildup, increased with time. Some transported material traversed the lamina cribrosa despite pressure elevation at the level tested. Reversal of transport blockade occurred rapidly after normalization of intraocular pressure.