International Ophthalmology 20: 197-204, 1996. 197 @ 1996 KluwerAcademic Publishers. Printed in theNetherlands. Prothrombotic states associated with retinal venous occlusion in young adults Ahmed M. Abu E1-Asrar 1, Abdul-Kareem A1-Momen 2, Saleh A1-Amro 1, Abdel Galil M. Abdel Gader 3 & Khalid E Tabbara 1 Departments of 1 Ophthalmology, 2 Medicine (Division of Hematology), and 3 Coagulation Research Laboratory, College of Medicine, King Saud University, Riyadh, Saudi Arabia Accepted28 August 1996 Key words: retinal vein occlusion, young adults, antiphospholipid antibodies, anticoagulant system, Factor XII, blood viscosity Abstract Background. The etiology of retinal venous occlusion in young patients is not well understood although thrombosis does occur histologically. A search for the risk factors that may lead to thrombosis is highly desirable may contribute to our understanding of the pathogenesis of this complication and may improve our therapeutic strategies. Methods. We studied 17 patients with retinal venous occlusion. All patients were under 45 years of age (mean 37.8 4- 7.1). Antiphospholipid antibodies (APAs) and certain hemostatic factors were determined. The results obtained in these patients were compared to those of normal controls. Results. We found APAs in 8 out of 17 patients compared to 5 out of 60 controls (p = 0.0002). In patients with major trunk occlusion, there was a trend for the presence of APAs in those with poor visual acuity at presentation. Deficiencies of the coagulation inhibitor proteins C and S and antithrombin III activities were detected in 6 patients, and reduced levels of Factor XII were found in 4 patients. Levels of hematocrit, erythrocyte sedimentation rate, Fibrinogen, cq-globulin, and ct2-globulin were significantly higher in patients compared to the controls (p -- 0.019; 0.014; 0.0001; 0.011; 0.047), indicating increased blood viscosity in patients with retinal venous occlusion. Conclusion: Prothrombotic changes in the form of APAs and/or deficiencies of coagulation inhibitors and Factor XII may contribute to the etiology of retinal venous occlusion in young adults. Young patients with retinal venous occlusion should be evaluated for these prothrombotic states. Introduction Retinal venous occlusion occurs most commonly in the elderly. However, it' may also occasionally afflict the young age group. Hayreh and associates [1] found 131 (12%) cases out of 1,108 patients with retinal venous occlusion under 45 years of age. Retinal venous occlu- sion in young persons is not a totally benign disorder, and many patients suffer a significant, permanent visu- al loss [2-4]. The pathogenesis of retinal venous occlusion in young adults is not well understood, but prima- ry thrombosis does occur histologically [5, 6]. In 1845 Virchow [7] recognized that three major fac- tors play a role in thrombus formation: changes in blood flow, changes in the vessel wall, and changes in the circulating blood. Patients recognized as being at increased risk of thrombus formation have been termed as having a 'hypercoagulable state'. Many con- genital, and acquired blood protein defects are now known to account for hypercoagulability and thrombo- sis. These prothrombotic disorders include deficiencies in the physiological anticoagulants antithrombin III, protein C and protein S, defects in fibrinolytic mecha- nisms, and the presence of antiphospholipid antibodies (APAs) [8]. In addition, abnormalities of blood vis- cosity have also been reported in patients with retinal venous occlusion [9, 10]. We carried out a prospective study to assess the prothrombotic states that may play a role in the patho- genesis of retinal venous occlusion in young adults.