[Thrombin-antithrombin III complex. Cause of venous vascular occlusion of the retina]

The influence of a disturbed hemostasis as one of the causes of retinal vein occlusions is still controversial. We investigated the functional state of the coagulation system in 16 patients, 7 with a nonischemic and 9 with an ischemic retinal vein occlusion, with an enzyme-linked immunosorbent assay for the determination of thrombin-antithrombin III complex (TAT). Patients with a history of thromboembolic disease, raised blood pressure and/or badly managed diabetes mellitus were excluded from the investigations. In healthy individuals the plasma concentration is 1.45 ng/ml +/- 0.4 (mean value +/- SD), ranging from 1.0 to 4.1 ng/ml. In our patients we measured TAT concentrations ranging from 2.0 to 48.0 ng/ml. In 2 of 7 plasma samples from patients with nonischemic retinal vein occlusion (2.1-6.3 ng/ml, mean = 3.3, SE +/- 0.6) and in 6 of 9 in ischemic retinal vein occlusion (2.0-48.0, mean = 13.2, SE +/- 5.1) TAT concentrations were found to be increased. These data indicate that disturbed hemostasis may be involved in retinal vein occlusion, especially that caused by ischemia. Furthermore, TAT may be useful in differentiating ischemic from nonischemic retinal vein occlusion.