Capillary density and retinal diameter measurements and their impact on altered retinal circulation in glaucoma: a digital fluorescein angiographic study.
OBJECTIVE
Normal pressure glaucoma (NPG) patients exhibit prolonged retinal arteriovenous passage times in fluorescein angiography and colour Doppler imaging suggests increased resistance downstream from the central retinal and posterior ciliary arteries. The aim of the study was to elucidate the morphological source of decreased perfusion and increased resistance of the ocular circulation in NPG.


METHODS
Retinal arteriovenous passage time (AVP) and peripapillary arterial and venous diameters were measured in digital scanning laser fluorescein angiograms. For estimation of retinal capillary density the area of the foveal avascular zone (FAZ) and the perifoveal intercapillary area (PIA) was quantified. 36 patients with NPG (mean age 57 (SD 13) years) and 21 healthy subjects (mean age 51 (13) years) were enrolled in the comparative study.


RESULTS
In NPG patients the AVP (2.55 (1.1) seconds) was significantly prolonged (p<0.001) when compared with healthy subject data (AVP: 1.70 (0.39) seconds). No differences for arterial or venous diameter, FAZ, and PIA were observed in NPG patients compared with healthy subjects. FAZ, PIA, arterial and venous diameter were not correlated with visual field indices (except venous diameter with PSD, r=0.35 (p<0.05)) or cup to disc ratios. AVP was significantly correlated (p<0.05) with the size of the optic nerve head (r=-0.28), visual field indices (MD: r=-0.3; PSD: r=0.3; CPSD: r=0.3), and contrast sensitivity (r=-0.34).


CONCLUSIONS
AVP times are significantly prolonged in NPG. The slowing of the retinal transit does not result from capillary dropout, or changes of peripapillary arterial or venous diameters with increased vascular resistance.
Arend
O
O
Department of Ophthalmology, Medical School of the Technical University of Aachen, Pauwelsstrasse 30, 52057 Aachen, Germany. oliver.arend@post.rwth-aachen.de
Remky
A
A
Plange
N
N
Martin
B J
BJ
Harris
A
A
D001783:Blood Flow Velocity; D002196:Capillaries / Q000473:pathology; D005260:Female; D005902:Glaucoma, Open-Angle / Q000473:pathology* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012161:Retinal Artery / Q000473:pathology; D012169:Retinal Vein / Q000473:pathology; D014655:Vascular Resistance