title: Prolonged postocclusive hyperemia response in patients with normal-tension glaucoma.
abstract: BACKGROUND
  It is believed that endothelial dysfunction may be a link between systemic and ocular dysregulation in glaucoma. The aim of this study was to evaluate peripheral vascular reactive hyperemia in response to occlusion test and to correlate peripheral vascular findings with retrobulbar hemodynamics parameters in patients with normal-tension glaucoma.
  
  
  METHODS
  Forty-eight patients with normal-tension glaucoma (mean age 58.1 years, 38 women) and 40 control subjects (mean age 54.1 years, 36 women) were subjected to a brachial arterial occlusion test and color Doppler imaging (LOGIQ 9, GE Medical Systems) of the retrobulbar arteries. Finger hyperemia was assessed by using a 2-channel laser Doppler flowmeter (MBF-3D, Moor Instruments, Ltd.). Time parameters (time to peak flow, half-time of hyperemia, time of recovery) and amplitude parameters (maximum hyperemia response, biological zero) of the post-occlusive reactive hyperemia signal pattern as well as velocities and resistance index of the ophthalmic, central retinal, and short posterior ciliary arteries were evaluated and compared between study groups.
  
  
  RESULTS
  In glaucoma patients, time to peak flow and half-time of hyperemia were significantly longer (21.4 vs. 12.0 s, p=0.02 and 74.1 vs. 44.2 s, p=0.03, respectively) and biological zero was significantly lower (2.4 vs. 3.2, p=0.01) comparing with healthy subjects. In glaucoma patients, peak-systolic and end-diastolic velocities of central retinal artery were significantly lower (12.8 vs.14.1, p=0.03 and 3.9 vs. 4.7, p=0.01, respectively) and resistance index of this artery was significantly higher (0.69 vs. 0.67, p=0.03) compared to controls. In the glaucoma group, maximum hyperemic response was negatively correlated with the resistance index of temporal short posterior ciliary arteries (r=-0.4, p=0.01), whereas in the control group half-time of hyperemia was negatively correlated with end-diastolic velocity of the central retinal artery (r=-0.3, p=0.03).
  
  
  CONCLUSIONS
  Arterial occlusion test elicited a prolonged systemic hyperemia response in patients with glaucoma as compared with healthy subjects. Retrobulbar blood flow alterations in glaucoma patients may be related to systemic vascular dysregulation.
authors.affiliation: Department of Ophthalmology, Military Institute of Medicine, Warsaw, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Wierzbowska
authors.affiliation: Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Stanisław
authors.initials: S
authors.lastname: Wojtkiewicz
authors.affiliation: Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Zbieć
authors.affiliation: Department of Cardiology, Military Institute of Medicine, Warsaw, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Wierzbowski
authors.affiliation: Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Adam
authors.initials: A
authors.lastname: Liebert
authors.affiliation: Nałęcz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.
authors.forename: Roman
authors.initials: R
authors.lastname: Maniewski
mesh_terms: D005260:Female; D005901:Glaucoma / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D018615:Ultrasonography, Doppler, Color