Improvement of visual acuity in patients suffering from diabetic retinopathy after membrane differential filtration: a pilot study

Background: Membrane differential filtration is an extracorporeal treatment procedure which eliminates high molecular weight proteins and lipids from the blood. This pilot study was initiated to investigate the short-term eff ects on blood rheology and visual function in patients suffering from diabe tic retinopathy. Methods: Six patients with non-proliferative diabetic retinopathy, clinical ly significant macular edema (five patients, nine eyes) and inactive prolif erative diabetic retinopathy (one patient, one eye) underwent a single trea tment with a hollow fiber secondary plasma filter. The main parameter measu red was visual acuity prior to and after treatment. Biochemical and rheolog ical parameters (whole blood and plasma viscosity, and erythrocyte aggregat ion) were also measured. The mean follow-up was 25 (range 4-90) days after treatment. Results: The mean improvement of visual acuity was 1.4 lines (SD 0.8 lines, p = 0.002) 24 h after therapy. This remained stable during the follow-up p eriod, The rheological measures were significantly lowered. A significant r eduction of total protein, fibrinogen, IgG, IgM, IgA, alpha-2-macroglobulin , total cholesterol, LDL and HDL was found. Conclusion: This study demonstrates the rheological impact of membrane diff erential filtration. It was shown that rheological changes correlated with clinical improvement in patients suffering from diabetic retinopathy with c linically significant macular edema. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.