Optic nerve head blood flow in chronic experimental glaucoma
H. A. Quigley, R. M. Hohman, R. Sanchez and E. M. Addicks
We used the tritiated iodoantipyrine method to estimate blood flow in the
retina, optic nerve head, and retrobulbar optic nerve in monkey eyes.
Twelve eyes with short-term intraocular pressure (IOP) elevation and nine
eyes with long-term (up to 20 months) IOP elevation were compared with
their fellow normal eyes. The eyes with long-term glaucoma were staged for
degree of optic nerve damage according to disc cup size, nerve fiber layer
atrophy, and histologic estimates of the remaining number of nerve fibers.
At normal IOP levels, there were only minor differences in blood flow in
the superior, inferior, and middle nerve head sections. In eyes with
short-term IOP elevation, nerve head blood flow was normal, unless IOP
exceeded 75 mm Hg. Above this level, a progressive decrease in nerve head
blood flow was measured. Mean blood flow in the nerve head of eyes with
long-term glaucoma was not significantly different from that in the normal
fellow eyes. Some animals had small increases in blood flow, while others
had small decreases. These differences from normal did not correlate with
the amount or location of optic nerve damage. Our data do not support
decreased blood flow as part of the pathogenesis of long-term experimental
glaucoma.
