Different types of therapy having haemorheological effects in patients with impairment of blood supply to the retina

In a controlled, randomised, double-blind study, 71 patients with acute occlusion of retinal vessels (26 arterial, 45 venous) were treated with a basic therapy (BT: pentoxifylline + prednisolone) whereby in accordance with the randomisation, in normotensive patients additional therapy consisted of hypervolaemic haemodilution (HHD) with dextran 40, and in hypertensive patients with or without signs of cardiac insufficiency of isovolaemic haemodilution (IHD) with human albumin. The following parameters were determined before and during therapy: blood chemistry (PCV, erythrocyte count, erythrocyte volume, platelet count, plasma fibrinogen), haemorheoogy (apparent viscosity of whole blood at the shear rates 0.03 s⁻¹, 1,24 s⁻¹ and 49.4 s⁻¹, plasma viscosity, erythrocyte flexibility), platelet function test (ADP-induced platelet aggregation, spontaneous aggregation of platelets by the method of BREDDIN (PAT III), coagulation test (PT, PTT, TCT, RCT), visual function (visual acuity, field of view, analogue scale). None of the therapeutical methods used was able to modulate all the haemorheological parameters exclusively in the sense of improving the flow properties of the blood. Erythrocyte flexibility increased significantly with BT, whereas no significant change was detected with the combination of BT and IHD, and in contrast, there was a significant decrease with the combination of BT and HHD for the period of treatment by dextran infusion. The apparent viscosity of whole blood at the low shear rate remained virtually unchanged with BT, while it decreased with the combination of BT and HHD, but showed the most pronounced decrease with the combination of BT and IHD. Comparison of the haemorheological efficacy of these methods of therapy showed that the most favourable conditions for an improvement of function in impairment of blood supply to the retina were provided by the combination of BT and IHD. Clinical assessment of function showed that no marked differences in the results in arterial impairment of blood supply to the retina could be detected. For impairment of venous retinal blood flow, an increase in visual acuity and more favourable fields of view were initially found with all types of therapy. After 6 months, however, the functional results were better in patients treated with BT+IHD. Furthermore, secondary glaucoma occurred less often with this treatment.