Effect of dorzolamide and timolol on ocular pressure: blood flow relationship in patients with primary open-angle glaucoma and ocular hypertension.
OBJECTIVE
The authors have reported previously that a study population, consisting of patients with glaucoma and ocular hypertension, is characterized by an impaired association between ocular blood flow parameters and systemic blood pressure, indicative of abnormal autoregulation. Here they report on the effects of dorzolamide and timolol on ocular pressure/flow relationships to test the hypothesis that these drugs improve autoregulation.


METHODS
One hundred forty patients with primary open-angle glaucoma or ocular hypertension were included in a clinical trial in a controlled, randomized double-masked study in two parallel groups. Seventy patients were randomly assigned to receive timolol, and 70 patients were randomly assigned to receive dorzolamide for a 6-month period. Scanning laser Doppler flowmetry was used to measure blood flow in the temporal neuroretinal rim and the cup of the optic nerve head. Pulsatile choroidal blood flow was assessed using laser interferometric measurement of fundus pulsation amplitude. The association between blood flow parameters and systemic blood pressure was compared before and after the 6-month treatment period.


RESULTS
Before treatment a significant association was observed between ocular blood flow parameters and systemic blood pressure in both parallel groups (r = 0.23-0.42). All regression lines between ocular hemodynamic parameters and systemic blood pressure were less steep after treatment with either dorzolamide or timolol (r = 0.03-0.24).


CONCLUSIONS
The present study indicates that intraocular pressure reduction with timolol or dorzolamide is associated with normalization of the ocular pressure/flow relationship. Whether this is related to the beneficial effects of IOP-lowering therapy in glaucoma remains to be established. (ClinicalTrials.gov number, NCT00991822.).
Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
Gabriele
G
Fuchsjäger-Mayrl
Michael
M
Georgopoulos
Anton
A
Hommer
Günther
G
Weigert
Berthold
B
Pemp
Clemens
C
Vass
Gerhard
G
Garhöfer
Leopold
L
Schmetterer
D000368:Aged; D000959:Antihypertensive Agents / Q000008:administration & dosage*; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology; D002829:Choroid / Q000098:blood supply; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005902:Glaucoma, Open-Angle / Q000188:drug therapy / Q000503:physiopathology*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007368:Interferometry; D007429:Intraocular Pressure / Q000187:drug effects*; D017078:Laser-Doppler Flowmetry; D007834:Lasers; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000188:drug therapy / Q000503:physiopathology; D009898:Optic Disk / Q000098:blood supply; D009901:Optic Nerve Diseases / Q000188:drug therapy / Q000503:physiopathology*; D012039:Regional Blood Flow; D013449:Sulfonamides / Q000008:administration & dosage*; D013876:Thiophenes / Q000008:administration & dosage*; D013999:Timolol / Q000008:administration & dosage*
D000959:Antihypertensive Agents; D013449:Sulfonamides; D013876:Thiophenes; D013999:Timolol; C062765:dorzolamide