Abstract
PurposeAbnormal autoregulation of optic nerve head blood flow (ONHBF) has been postulated to play an important role in primary open‐angle glaucoma (POAG). We used laser Doppler flowmetry (LDF) to estimate quantitatively the ONHBF and compared ONHBF autoregulation between glaucoma patients and healthy controls during isometric exercise.MethodsForty patients with POAG and 40 healthy age‐ and sex‐matched subjects underwent three periods of isometric exercise, each consisting of 2 min of handgripping. Optic nerve head blood flow (ONHBF) was measured continuously using LDF. Systemic blood pressure, intraocular pressure and ocular perfusion pressure were assessed in all participants.ResultsIsometric exercise was associated with an increase in ocular perfusion pressure during all handgripping periods in both groups (p < 0.001). However, there was no change in ONHBF in either group. Three of the glaucoma patients and two of the healthy subjects showed a consistent 10% decrease in blood flow during isometric exercise, in spite of an increase in their blood pressure. This difference between groups was not significant (p = 0.61). Four other glaucoma subjects showed a consistent increase in blood flow of more than 10% during isometric exercise, whereas this was not seen in healthy subjects (p = 0.035).ConclusionThis study suggests that abnormal ONHBF autoregulation is more often seen in patients with POAG than healthy control subjects. The relationship to the glaucoma disease process is currently unknown and requires further investigation.
Highlights
Abnormal autoregulation of the optic nerve head blood flow (ONHBF) has been implicated in the pathophysiology of primary open-angle glaucoma (POAG) (Flammer & Mozaffarieh 2008; Harris et al 2008; Cherecheanu et al 2013)
We investigated whether patients with POAG have abnormal autoregulation of ONHBF during isometric exercise compared to healthy age- and sexmatched control subjects
0.97 1.0 0.03 0.16 0.05 0.72 0.53 0.01 0.002
Summary
Abnormal autoregulation of the optic nerve head blood flow (ONHBF) has been implicated in the pathophysiology of primary open-angle glaucoma (POAG) (Flammer & Mozaffarieh 2008; Harris et al 2008; Cherecheanu et al 2013). Measuring ONH blood flow (ONHBF) autoregulation is challenging It is technically difficult because of the complex angio-architecture of the optic nerve head region (Mackenzie & Cioffi 2008). The second challenge relates to the stimuli used to modify OPP, because many interventions are too invasive to be used in elderly patients with eye disease. Both e36 isometric exercise (Movaffaghy et al 1998; Schmidl et al 2012, 2013a; Boltz et al 2013a,b,c) and postural change (Shiga et al 2013) have been used to increase OPP. Experimental increase in intraocular pressure (IOP) (Pillunat et al 1997; Riva et al 1997; Schmidl et al 2012, 2013b; Boltz et al 2013c; Hashimoto et al 2017a,b) and thighcuff release (Ikemura et al 2015) has been used to decrease OPP in humans
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