Effects of Therapeutic Apheresis on the Elongation of Erythrocytes in Patients With Age Related Macular Degeneration

Abstract

Abstract: : Purpose: Therapeutic apheresis is able to eliminate high molecular weight proteins and lipids from the blood in order to improve choroidal perfusion and might represent a new treatment option for patients with dry age–related macular degeneration (AMD). A positive effect on the course of the disease was demonstrated in randomized trials including an interim analyses of a large multicenter study. Using different procedures, proteins and lipids are removed from the blood to improve hemorheologic parameters such as whole blood viscosity, plasma viscosity and erythrocyte aggregation. In this study the changes of the elongation of erythrocytes (EE) after therapeutic apheresis as an additional hemorheologic parameter are examined. Methods: With the Myrenne Rheodyn shear–stress diffractometer (SSD), flow–induced cell extension can be assessed in nucleus–free erythrocytes in a high viscosity carrier fluid. The erythrocyte elongation was measured for a total of 33 patients with exsudative or dry AMD before and after therapeutic apheresis with the SSD under defined shear–strength levels between 0.3 and 60 Pa. Different techniques of therapeutic apheresis like rheopheresis (membrane differential filtration), plasma exchange and immune adsorption were examined. Results: Therapeutic apheresis is able to influence erythrocyte elongation. The most effective technique was rheopheresis (membrane differential filtration) which was superior to plasma exchange and erythrocyte aggregation. The changes of EE were most striking and long lasting for patients who were treated for the first time with rheopheresis. Conclusions: Therapeutic apheresis is able to change different parameters in favor of an improvement in hemorheology. Distinctly reduced erythrocyte aggregation, plasma viscosity and whole–blood viscosity levels are evident and may lead to an optimization of choroidal perfusion. With the elongation of the erythrocytes a new parameter has been identified which might contribute to the clinical improvement in these patients demonstrated in previous studies. This might be achieved through an improvement in the axial migration at the microcirculatory level.

Keywords: age-related macular degeneration