Abstract
Purpose: :
We have recently performed a study investigating the ocular hemodynamic effects of dorzolamide and timolol in patients with primary open angle glaucoma (POAG) and ocular hypertension (OHT). The baseline data of this trial (Fuchsjager–Mayrl et al. IOVS 2003;43:2185–90) as well as the results on the effects of timolol and dorzolamide on ocular hemodynamic parameters (Fuchsjager–Mayrl et al. 2005 BJO 89:1293–7.) have been presented previously. Here we report on the effects of dorzolamide and timolol on the association between systemic blood pressure and ocular hemodynamic parameters.
Methods: :
The study was performed in a randomized, double–masked parallel group design in patients with either POAG or OHT and an untreated intraocular pressure (IOP) greater or equal 22 mmHg. Patients were randomized to receive either timolol (n=70) or dorzolamide (n=70) for 6 months. Neuroretinal rim blood flow (BFrim) and optic disk blood flow (BFdisc) were assessed with confocal scanning laser Doppler flowmetry using the Heidelberg Retina Flowmeter (HRF) and pulastile choroidal blood flow was assessed with measurement of ocular fundus pulsation amplitude (FPA)using laser interferometry. The association between BFrim, BFcup and FPA on the one hand and mean arterial blood pressure (MAP) on the other hand was compared at baseline and after 6 months of treatment using linear regression analysis.
Results: :
As compared to an age– and sex–matched healthy control group patients with POAG or ocular hypertension showed an abnormal association bewteen BFrim, BFcup, FPA and MAP (Fuchsjager–Mayrl et al. IOVS 2003). An increase in BFrim, BFcup and FPA was only seen with dorzolamide, but not with timolol (Fuchsjager–Mayrl et al. BJO 2005). Both drugs, however, altered the association between BFrim, BFcup, FPA and MAP (p < 0.05 each) towards a normalization. This effect was dependent on the achieved IOP reduction and not associated with the increase in ocular blood flow parameters.
Conclusions: :
The data of this analysis indicate that vascular dysregulation as seen in POAG and/or OHT can be reduced with both timolol and dorzolamide treatment. This effect appears to be unrelated to the effects of the drugs on ocular blood flow, but is associated with the IOP lowering efficacy of timolol and dorzolamide.
Keywords: optic disc • clinical (human) or epidemiologic studies: risk factor assessment • pharmacology