Intraocular pressure effects on optic nerve-head oxidative metabolism measured in vivo.
The effects of acute intraocular pressure (IOP) on the reduction/oxidation ratio of cytochrome a, a3 were measured from intact cat optic nerve by microfiber reflection spectrophotometry. This enabled the real-time analysis of optic nerve-head oxidative metabolism following IOP or mean arterial pressure (MAP) changes. Findings included: (1) cytochrome a, a3 became more reduced and relative blood volume decreased at lower perfusion pressures, even at IOP of less than 20 mm Hg; (2) metabolic inhibition began at variable perfusion pressures but invariably progressed as perfusion pressure declined; and (3) increased IOP or decreased MAP caused metabolic inhibition. These findings demonstrate that: (1) optic nerve metabolic dysfunction is possible at low IOPs; (2) lowering IOP can reverse metabolic dysfunction; (3) the metabolic response is dependent on IOP and/or MAP changes; and (4) the metabolic inhibition is related to optic nerve ischemia.
Novack
R L
RL
Duke University Eye Center, Durham, NC.
Stefánsson
E
E
Hatchell
D L
DL
D000818:Animals; D001810:Blood Volume / Q000502:physiology; D002415:Cats; D003576:Electron Transport Complex IV / Q000378:metabolism; D005260:Female; D007429:Intraocular Pressure; D008297:Male; D009898:Optic Disk / Q000098:blood supply / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D010477:Perfusion; D013053:Spectrophotometry
D003576:Electron Transport Complex IV