Neuronal activity influences hemodynamics in the paraoptic short posterior ciliary arteries: a comparison between healthy and glaucomatous subjects.
OBJECTIVE
Perfusion of the retina adapts to metabolic demand by neurovascular coupling. The present study was an investigation of the presence of neurovascular coupling in the anterior part of the optic nerve in healthy subjects and patients with glaucoma.


METHODS
Retrobulbar blood flow velocities were determined by color Doppler imaging (CDI). Peak systolic and end diastolic velocities (PSVs and EDVs) in the central retinal artery (CRA) or the short posterior ciliary artery (SPCA) were the primary readout. CDI measurements were performed shortly before, during, immediately after, 60 seconds after, and 120 seconds after a 10-Hz flicker stimulation of the retina.


RESULTS
Thirty-five patients with glaucoma and 44 healthy control subjects were included in the study. In the SPCA of healthy control subjects, flicker stimulation led to an increase in PSV from 9.7 +/- 0.8 to 12.5 +/- 0.8 cm/s (P < 0.001; n = 24) and of EDV from 2.4 +/- 0.3 to 3.6 +/- 0.3 cm/s (P < 0.001; n = 24). This effect was not detectable in patients with glaucoma. In the CRA, flicker light led to an increase in EDV from 2.1 +/- 0.2 to 3.0 +/- 0.3 cm/s (P = 0.002; n = 20) in healthy volunteers and from 1.3 +/- 0.2 to 2.0 +/- 0.2 cm/s in patients with glaucoma (P = 0.004; n = 15). PSV was not affected by flicker stimulation in either the healthy volunteers or patients with glaucoma.


CONCLUSIONS
The data indicate the presence of neurovascular coupling in the vascular bed supplied by the paraoptic SPCA. The response pattern to the flicker stimulus differs between healthy subjects and individuals with glaucoma.
Zeitz
Oliver
O
Universitätsklinikum Hamburg-Eppendorf, Klinik und Poliklinik für Augenheilkunde, Hamburg, Germany. oliver.zeitz@googlemail.com
Mayer
Jeannette
J
Hufnagel
Doreen
D
Praga
Ralf
R
Wagenfeld
Lars
L
Galambos
Peter
P
Wiermann
Anne
A
Rebel
Claudia
C
Richard
Gisbert
G
Klemm
Maren
M
D000328:Adult; D001783:Blood Flow Velocity; D019842:Ciliary Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000175:diagnosis / Q000503:physiopathology*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D009900:Optic Nerve / Q000502:physiology*; D009901:Optic Nerve Diseases / Q000175:diagnosis / Q000503:physiopathology*; D010775:Photic Stimulation; D012160:Retina / Q000502:physiology; D012161:Retinal Artery / Q000000981:diagnostic imaging / Q000502:physiology; D018615:Ultrasonography, Doppler, Color