CARBONIC ANHYDRASE INHIBITION AND ITS EFFECT ON RETINAL MICRO- AND MACROCIRCULATION

A.S Bernd1, L. Pillunat1, W. Vilser2, T. Riemer2, M. Eichhorn3 and A. Böhm4

1University Eye Clinic Hamburg, Germany, 2Technical University Ilmenau, 3Institute of Anatomy, University of Erlangen, 4Department of Ophthalmology, University of San Diego

Purpose: The aim of the study was to elucidate the effect of carbonic anhydrase inhibitors on blood flow in retinal vessels and on retinal capillary blood flow. Methods: 10 healthy subjects (21-49 y) received orally 1000 mg acetazolamide. At baseline intraocular pressure (IOP), blood pressure, fundus photography and capillary retinal blood flow were examined. Pulsatile ocular blood flow were recorded by using the OBF-system (UK)Ltd. Retinal vessel diameter was measured by the Visualis-System. Retinal capillary blood flow was measured by Heidelberg-Retina-Flowmeter. All measurements were repeated at the peak plasma time of acetazolamide. For statistical analysis the Wilcoxon-test was applied.

Results: IOP decreased significantly (p<0.05) from x=12.2 mmHg to 8.5 mmHg. The diameter of retinal veins did not change significantly from x=345 mm to x=339 mm and the retinal arteries by a mean of x=5 mm. Retinal capillary blood velocities, volumes, flow also did not change significantly (delta velocity x=0.74AU, delta volume=1.61AU, delta flow x=1.0AU). Pulsatile ocular blood flow increased significantly (p<0.01) from x=717 ml/min to x=860 ml/min.

Conclusions: The results showed the expected drop in IOP. Retinal hemodynamics, however, did not show any changes within the macrocirculation nor in the capillary retinal vacsulature. This might be due to an effective autoregulation of the retinal vascular bed.