Abstract
Abstract: :
Purpose: To examine the influence of dorzolamide on autoregulative changes of the diameter of retinal vessels during decrease of perfusion pressure. Methods:: 14 untreated patients with POAG (mean age 61.6 y, mean IOP = 22.4 mm Hg) and 13 volunteers without eye diseases (mean age 61.2 y, mean IOP = 13.8 mm Hg) have been enrolled in the study. Changes of the diameter of a segment of a retinal artery and vein were continuously measured by a Retinal Vessel Analyzer (RVA, IMEDOS / Germany) before, during and after an artificial elevation of IOP to 38 mm Hg during 100 sec. The measurement was repeated for the POAG patients after 4 weeks therapy with dorzolamide eye drops t.i.d. Results: Changes of the diameter of the artery caused by reduction of perfusion pressure could not be found in volunteers but in untreated POAG patients (p = 0.04). These changes of arterial diameter were not detectable after 4 weeks therapy with dorzolamide. The diameter of the veins did not change in volunteers and untreated POAG patients during elevation of IOP, followed by a strong dilatation peak (+8%, p<0.006) immediately after decrease of IOP. Venous diameter in treated glaucomatous eyes increased already during elevation of IOP (+ 3%, p = 0.03), followed by an identical peak (+8 %, p<0.01) after IOP elevation. Dorzolamide lowered the IOP to 16.8 mm Hg (p = 0.001). Conclusion: Dorzolamide influences the autoregulation of the retinal microcirculation. The arterial vessel diameter in dorzolamide treated POAG patients is able to compensate the disturbance and diameter changes were not detectable. The change of the venous reaction in dorzolamid treated eyes during IOP elevation indicates probably a different behaviour of the capillaries caused by increased pCO2 in the retina.
Keywords: 554 retina • 331 blood supply • 390 drug toxicity/drug effects