The aim of this study was the assessment of physiological venous refle
xes in systemically hypertensive and normotensive subjects with primar
y open-angle glaucoma. The experimental group consisted of 20 normoten
sive and 20 untreated systemically hypertensive patients with open-ang
le glaucoma. The control group consisted of 31 volunteers divided into
two subgroups: 16 control normotensives and 15 untreated hypertensive
s. The assessment of venous tone changes was performed by testing veno
us reflexes, Venoconstriction responses to physiological stimuli were
significantly decreased in normotensive glaucoma patients, compared to
normotensive controls [for the Valsalva manoeuvre 93.4 +/- 80.2 vs, 4
13.3 +/- 335.4 venoconstrictive units (VCUs), p = 0.02, and for a deep
breath 89.1 +/- 100.1 vs. 316.8 +/- 343.2 VCUs, p = 0.03]. The intens
ity of venous reflexes in hypertensive glaucoma patients did not diffe
r significantly from that seen in hypertensive controls, due to a sign
ificantly weaker reflex venoconstriction in hypertensive controls when
compared to normotensive controls subjects. This study confirmed the
presence of venous dysregulation in subjects with primary open-angle g
laucoma and visual field loss as a part of an autonomic dysfunction. S
ystemic hypertension does not make this condition worse.