Objective-To review the obstetric and gynaecological problems in women with congenital coagulopathics. Design-Retrospective rcview.

Various haemostatic factors have been implicated in retinal vein occlusion -for example, increased factor VIII which has a coagulant activity, reduced antithrombin III which is an inhibitor of blood coagulation, and increased fibrinopeptide A which indicates the activation of blood coagulation.19 23 Recently, low activated protein C resistance has been described in patients with thrombotic tendencies.24 Inheritance of this deficiency is thought to be considerably more common in the general population (3-6%), than deficiencies of proteins C, S, and antithrombin III. Although a case of activated protein C resistance and CRVO has been described, no cohort studies of the prevalence of this abnormality in CRVO have been performed.25In this study, only patients with CRVO (or its variant, hemiretinal vein occlusion) were examined, thereby removing the influence of patients with branch vein occlusions on the results. The patients were age matched to individuals attending population surveys,26 thereby reducing bias from employing hospital based controls. For the first time activated protein C resistance was investigated in a group of patients with CRVO.24 27 Finally, the natural history of raised viscosity was studied by serial measurements over a year after onset of the condition. Patients and methodsEighty seven patients with CRVO were examined prospectively (including 10 patients with hemiretinal vein occlusion which was considered as a variant of CRVO). The patients

No abstract

The influence of multiple systemic factors upon the blood velocities obtained from the orbital circulations was investigated. The velocities obtained by colour Doppler imaging from the ophthalmic artery, central retinal artery, and vein from 95 ophthalmologicaliy healthy volunteers were analysed. The effects of age, systemic blood pressure, and smoking habit were examined. In 24 volunteers blood viscosity was also measured and its relation with blood velocity assessed. Age was weakly negatively correlated with the blood velocities in the ophthalmic artery and weakly positively correlated with resistance to flow in the retinal circulation. Systolic blood pressure showed a positive correlation with the peak systolic velocities in the arteries while cigarette smoking was associated with lower ophthalmic artery velocities. Increased haematocrit and viscosity were positively correlated with resistance to flow proximal to the ophthalmic artery and red cell rigidity negatively correlated with the pulsatility of flow in the retinal vein. These results help to identify the roles of systemic conditions in the ocular circulation. The influence of blood viscosity on retinal venous flow may be relevant to the pathogenetic mechanisms of conditions such as central retinal vein occlusion. (BrJ Ophthalmol 1995; 79: 17-22) Colour Doppler imaging allows examination of the pulsatile velocity of blood in the orbital vessels'"3 and has been used in the investigation of a number of vascular ophthalmic disorders."9 Although the effects of posture3 and intraocular pressure5' 1 have been investigated, the effects of various systemic factors upon the blood velocities obtained by this technique are as yet unknown. In this study the influence of age, systemic blood pressure, smoking habit, and arteriopathy were examined in a control population to determine their effect on these haemodynamic variables.In addition, blood rheology, which may have a profound effect on the blood flow of the eye and has been implicated in number of ophthalmic vascular disorders"-'' was examined in a group of volunteers also examined by colour Doppler imaging. The relation between the rheology of the blood and its pulsatile velocities was therefore investigated and interpreted with reference to the pathogenesis of ocular diseases. Subjects and method SUBJECTSNinety five volunteers were examined to provide control data and consisted of staff of the ophthalmology or radiology department at the Western Infirmary Hospital, Glasgow and relatives of patients attending the ophthalmology outpatient department. The volunteers were asked for history of general medical and ocular conditions, drug usage. Smoking habit was recorded as one ofthe following: (1) Non-smoker, (2) ex-smoker, (3) smokes less than 20 cigarettes each day, (4) smokes at least 20 cigarettes each day, (5) pipe or cigar smoker.