Retinal arteriolar vascular reactivity in untreated and progressive primary open-angle glaucoma.
Purpose. To determine (1) the magnitude of retinal arteriolar vascular reactivity to normoxic hypercapnia in patients with untreated primary open-angle glaucoma (uPOAG) or progressive (p)POAG and in control subjects and (2) the effect of treatment with 2% dorzolamide on retinal vascular reactivity in uPOAG. Methods. The sample comprised 11 patients with uPOAG (after undergoing treatment, they became treated (t)POAG), 17 patients with pPOAG (i.e., manifesting optic disc hemorrhage), and 17 age-similar control subjects. The partial pressure of end-tidal CO(2) (PetCO(2)) was stabilized at 38 mm Hg at baseline. After baseline (10 minutes), normoxic hypercapnia was then induced (15 minutes) with an automated gas flow controller. Retinal arteriolar and optic nerve head (ONH) blood hemodynamics were assessed. The procedures were repeated after treatment with 2% dorzolamide for 2 weeks in tPOAG. Results. Baseline arteriolar hemodynamics were not different across the groups. In control subjects, diameter, velocity, and flow increased (P < 0.001) in response to normoxic hypercapnia. There was no change in all three hemodynamic parameters to normoxic hypercapnia in uPOAG, whereas only blood flow increased (P = 0.030) in pPOAG. Vascular reactivity was decreased in uPOAG and pPOAG patients compared with that in control subjects. After treatment with topical 2% dorzolamide for 2 weeks, the tPOAG group showed an increase in diameter, velocity, and flow (P </= 0.04) in response to normoxic hypercapnia. Similar trends were noted for ONH vascular reactivity. Conclusions. A reduced magnitude of arteriolar vascular reactivity in response to normoxic hypercapnia was shown in uPOAG and in pPOAG. Vascular reactivity improved after dorzolamide treatment in POAG.
Venkataraman
Subha T
ST
Glaucoma and Retina Research Group, Department of Ophthalmology and Vision Sciences, University of Toronto, Toronto, Ontario, Canada.
Hudson
Chris
C
Rachmiel
Rony
R
Buys
Yvonne M
YM
Markowitz
Samuel N
SN
Fisher
Joseph A
JA
Trope
Graham E
GE
Flanagan
John G
JG
D000287:Administration, Topical; D000368:Aged; D001160:Arterioles / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D002257:Carbonic Anhydrase Inhibitors / Q000008:administration & dosage; D018450:Disease Progression; D005902:Glaucoma, Open-Angle / Q000188:drug therapy / Q000503:physiopathology*; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology; D007429:Intraocular Pressure / Q000187:drug effects; D017078:Laser-Doppler Flowmetry; D008875:Middle Aged; D009898:Optic Disk / Q000098:blood supply; D012039:Regional Blood Flow / Q000502:physiology; D012161:Retinal Artery / Q000502:physiology*; D013449:Sulfonamides / Q000008:administration & dosage; D013876:Thiophenes / Q000008:administration & dosage
D002257:Carbonic Anhydrase Inhibitors; D013449:Sulfonamides; D013876:Thiophenes; C062765:dorzolamide