Role of haemorheological factors in patients with retinal vein occlusion Francesco Sofi 1 , Lucia Mannini 1 , Rossella Marcucci 1 , Paola Bolli 2 , Andrea Sodi 3 , Barbara Giambene 3 , Ugo Menchini 3 , Gian Franco Gensini 1,2 , Rosanna Abbate 1 , Domenico Prisco 1 1 Department of Medical and Surgical Critical Care, Thrombosis Centre, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy; Center for the study at molecular and clinical level of chronic, degenerative and neoplastic diseases to DEvelop NOvel THErapies, University of Florence, Italy; 2 Don Carlo Gnocchi Foundation, IRCCS, Florence, Italy; 3 Department of Oto-Neuro- Ophthalmological Surgical Sciences, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy Summary Retinal vein occlusion (RVO) is an important cause of perma- nent visual loss. Hyperviscosity, due to alterations of blood cells and plasma components, may play a role in the pathogenesis of RVO.Aim of this case-control study was to evaluate the possi- ble association between haemorheology and RVO.In 180 RVO patients and in 180 healthy subjects comparable for age and gender we analysed the whole haemorheological profile: [whole blood viscosity (WBV), erythrocyte deformability index (DI), plasma viscosity (PLV), and fibrinogen].WBV and PLV were measured using a rotational viscosimeter, whereas DI was measured by a microcomputer-assisted filtrometer. WBV at 0.512 sec -1 and 94.5 sec -1 shear rates as well as DI,but not PLV, were found to be significantly different in patients as compared to healthy subjects.At the logistic univariate analysis,a significant Keywords Blood viscosity, haemodilution, haemorheology, retinal vein occlusion association between the highest tertiles of WBV at 94.5 sec -1 shear rate (OR: 4.91, 95%CI 2.95–8.17; p<0.0001),WBV at 0.512 sec -1 shear rate (OR: 2.31, 95%CI 1.42–3.77; p<0.0001), and the lowest tertile of DI (OR: 0.18, 95%CI 0.10–0.32; p<0.0001) and RVO was found. After adjustment for potential confounders,the highest tertiles of WBV at 0.512 sec -1 shear rate (OR: 3.23, 95%CI 1.39–7.48; p=0.006),WBV at 94.5 sec -1 shear rate (OR: 6.74, 95%CI 3.06–14.86; p<0.0001) and the lowest tertile of DI (OR: 0.20, 95%CI 0.09–0.44,p<0.0001) remained significantly as- sociated with the disease. In conclusion, our data indicate that an alteration of haemorheological parameters may modulate the susceptibility to the RVO,by possibly helping to identify patients who may benefit from haemodilution. Thromb Haemost 2007; 98: 1215–1219 Blood Coagulation, Fibrinolysis and Cellular Haemostasis Correspondence to: Francesco Sofi, MD, PhD Department of Medical and Surgical Critical Care Thrombosis Centre, University of Florence Viale Morgagni 85, 50134 Florence, Italy Tel.: +39 055 7949420, Fax: +39 055 7949418 E-mail: francescosofi@gmail.com Received April 4, 2007 Accepted after revision October 3, 2007 Prepublished online November 9, 2007 doi :10.1160/TH07–04–0247 © 2007 Schattauer GmbH, Stuttgart 1215 Introduction Retinal vein occlusion (RVO) is one of the commonest vision- threatening retinal vascular disorders (1, 2). Despite its relatively uncommon prevalence among the general population, RVO has a clinical relevance since it is an important cause of permanent vis- ual loss, especially in elderly people, and it has been reported to be associated with an increased risk of mortality from cardiovas- cular diseases (3).To date, the pathogenesis of RVO has not yet been determined. Atherosclerosis is considered to be the most important underlying condition and several risk factors associ- ated to the atherosclerotic process, including hypertension, dia- betes, and smoking habit, have been identified to play a role in the pathogenesis of the disease (2). In addition, several of the ac- quired and inherited risk factors for arterial and venous throm- botic diseases have been reported to be highly prevalent in RVO patients (4). We have previously demonstrated a significant as- sociation between some thrombophilic parameters and the oc- currence of RVO (5–7). An open issue in the pathogenesis of RVO is, to date, blood viscosity. Blood viscosity is a relevant factor in venous circu- lation and an impaired blood flow in a branch of the central reti- nal vein may be able to favour and/or precipitate RVO. Over the last few years, an increasing interest for the possible association