Vascular network changes in the retina with age and hypertension.
OBJECTIVE
To compare retinal arterial bifurcation geometry in normotensive and hypertensive subjects.


METHODS
A retrospective observational study.


METHODS
Fluorescein angiograms of normotensive (n = 13) and hypertensive (n = 12) subjects aged 30-80 years with uni-ocular retinal pathology were compared. Quantification of diameters of the parent, larger daughter and smaller daughter vessels (d0, d1 and d2, respectively) and of bifurcation angles (the angle between the two daughter arterioles, omega) of arteriolar bifurcations was performed from digitized retinal angiograms of the uninvolved eye. The relative diameters of parent and daughter vessels at bifurcations were summarized by junction exponents (x) such that d1x + d2x = d0x.


RESULTS
Junction exponents were similar for normotensives and hypertensives (means +/- SEM, 2.65 +/- 0.18 and 2.48 +/- 0.17), but analysis of covariance showed a parallel decrease in x in the two groups with age. A positive association was found between x and arteriolar microvascular density. Bifurcation angles were more acute in hypertensives (74 +/- 3 degrees) than in normotensives (84 +/- 3 degrees) and declined with increasing age in both groups.


CONCLUSIONS
The present findings indicate that ageing and possibly hypertension are associated with disadvantageous branching geometry in the human retinal vasculature, implying increased power costs of blood transport, uneven distribution of shear forces throughout the vascular tree and microvascular rarefaction. The present findings may have important implications for our understanding of the pathogenesis of vascular disease in ageing and hypertension and offer the prospect of a novel sensitive diagnostic approach to the cardiovascular system.
Department of Clinical Pharmacology, St. Mary's Hospital, London, UK.
A V
AV
Stanton
B
B
Wasan
A
A
Cerutti
S
S
Ford
R
R
Marsh
P P
PP
Sever
S A
SA
Thom
A D
AD
Hughes
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001794:Blood Pressure; D005260:Female; D005451:Fluorescein Angiography; D006801:Humans; D006973:Hypertension / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011859:Radiography; D012160:Retina / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012189:Retrospective Studies; D014655:Vascular Resistance