Regional optic nerve blood flow and its autoregulation.

An autoradiographic method (14C-iodoantipyrine autoradiography) was used to measure regional optic nerve blood flow (ONBF) under basal conditions in 11 adult female cats. Flow was measured in six regions of the optic nerve: (1) prelaminar, (2) laminar, (3) 1 mm post-laminar, (4) 4 mm post-laminar, (5) 6 mm post-laminar, and (6) intracranial optic nerve and chiasm. A gradient of flow rates was found with relatively high flow in the prelaminar, laminar, and 1-mm post-laminar optic nerve, and significantly lower flow in the 4- and 6-mm post-laminar nerve and in the intracranial optic nerve and chiasm. Blood flow in the 4- and 6-mm post-laminar nerve and in the intracranial nerve and chiasm was comparable to previously reported values for cerebral white matter in the cat. With alteration of mean arterial blood pressure (MABP), optic nerve blood flow demonstrated autoregulatory compensation in all areas.