Abstract
Purpose :
Autoregulation plays an important role in controlling blood flow in response to fluctuation of ocular perfusion pressure (OPP) and impaired autoregulation of ocular vascular beds has been reported to be involved in the pathogenesis of glaucoma and non-arteritic anterior ischemic optic neuropathy (NAION). However, autoregulation of human ocular vascular beds in response to OPP changes is not fully understood in healthy and diseased eyes. The purpose of this study was to investigate the dynamics of blood flow in the retina, choroid and optic nerve vascular beds in normal and eyes with optic neuropathy using a novel vacuum goggle device (Equinox Ophthalmic, Newport Beach, CA) which can induce an abrupt lowering of intraocular pressure (IOP).
Methods :
In this cohort study, eleven healthy subjects (mean age 39 years; range 26-65), two patients with NAION and 2 patients with glaucoma were studied using laser speckle flowgraphy (LSFG-NAVI, Softcare, Japan). Blood flow was measured at baseline, during acute reduction of IOP by 7.5mmHg for five minutes and after termination of the goggle vacuum for 3 minutes. We quantified the blood flow in the retinal arterioles, optic nerve head (ONH) tissue and choroid in normal regions and in locations of atrophy from optic neuropathy.
Results :
In 22 normal eyes, blood flow in the optic nerve, retina and choroid showed an initial transient increase during IOP drop, followed by a return to baseline flow within seconds during sustained goggle vacuum, followed by a transient decrease in blood flow at termination of vacuum when IOP increased (Friedman test and Dunn’s multiple comparison test; P < 0.05), indicating autoregulation. Conversely, in NAION and glaucomatous eyes, a sustained increase in retinal and optic nerve blood flow occurred in both atrophic and intact regions during IOP decrease from goggle vacuum, indicating an alteration in autoregulation that may be influenced by neurovascular coupling.
Conclusions :
We demonstrated strong autoregulation of blood flow in normal eyes but not in eyes with NAION and glaucoma. Vacuum goggles may provide a novel means to predict how much increase in ocular blood flow will result from lowering of IOP in individual eyes.
This is a 2020 ARVO Annual Meeting abstract.