Abstract
Abstract: :
Purpose: Systemic carboanhydrase inhibitor acetazolamide (AZ) reduces intraocular pressure (IOP), diminishes pH–value and leads to vasodilation. Aim of the present study was to investigate the effect of AZ on different ocular vascular beds. Methods: In a prospective study 32 healthy volunteers (16 male, 16 female) were included. The mean age was 23.9±3,3 years (20–39 years). Ocular perfusion parameters were determined temporal superiorly by the laser Doppler flowmeter according to Riva (LDF) in the neuroretinal rim, by scanning laser Doppler flowmeter (HRF) in the peripapillary retina, and retinal vessel diameters (VD) were measured with the retinal–vessel–analyzer (RVA). Additionally the OBF–system was used. Measurements were completed by determinations of heart frequency (HF), blood pressure (BP), pH–value, pO2, pCO2, O2–saturation, bicarbonate concentration and base excess. After baseline measurements 1000mg AZ were injected intravenously and measurements were repeated six times every 20 minutes. Statistical analysis was performed using ANOVA with repeated measurements (SPSS, Version 11.0). Results: HF and BP showed no significant changes. IOP was significantly reduced (P=0.035) from 15.6 mmHg to 12.5mmHg (20minutes), 14.0 (40min.), 13.7 (60min.), 13.1 (80min.), 13.1 (100min.) und 12.5 (120min.). Arterial VD increased from 127 µm to 130/132/130/129/132/130/130µm, respectively (P=0.004). LDF flow raised significantly from 18.1 AU (arbitrary units) to 20.9/22.6/20.7/20.3/22.7/23.2 and 21.1 AU, respectively (P=0.0001). Parameters pulse amplitude (P=0.491) and ocular blood flow (P=0.274) of the OBF–system showed no significant changes. HRF flow increased from 171 AU to 176 (20min.) and then dropped to 169/168/152/143 and 139 AU (P<0.00005), respectively. pH–value (P<0.00005), pCO2 (P=0.08), pO2 (P=0.01), O2–saturation (P=0,00005), bicarbonate concentration (P<0.00005) and base excess (P<0.00005) diminished within the follow–up period. Conclusions: 1000mg systemically applied acetazolamide lead to a vasodilation of retinal arteries and veins, an increase of blood flow in the neuroretinal rim of optic nerve head and a drop of parapapillary retinal blood flow. The different effect in different vascular beds might be due to different regulatory mechanisms or different distributions of carboanhydrase in the different vascular beds.
Keywords: blood supply • drug toxicity/drug effects • imaging/image analysis: clinical