ELEVATED ERYTHROCYTE AGGREGATION IN PATIENTS WITH CENTRAL RETINAL VEIN OCCLUSION AND WITHOUT CONVENTIONAL RISK-FACTORS

Background: Retinal venous circulation is characterized by the combina tion of a low flow state and a high vascular resistance, which would m ake it particularly dependent on blood viscosity. Erythrocyte aggregat ion is the chief determinant of blood viscosity at low shear rates. Re cent studies have demonstrated increased erythrocyte aggregation in ma ny systemic vascular disorders and also in retinal vein occlusion. Met hods: To assess the possible role of abnormal hemorheologic findings i n the pathogenesis of central retinal vein occlusion (CRVO), the autho rs retrospectively studied erythrocyte aggregation and hematocrit and fibrinogen levels in 33 patients with CRVO and without any known risk factors (diabetes, hypertension, smoking, hyperlipidemia, cardiovascul ar disease, glaucoma). Erythrocyte aggregation was assessed with a lig ht back-scattering method. Results were compared with those of a group of 33 age- and sex-matched controls. Results: Eleven (33%) of the 33 patients with CRVO had abnormal hemorheologic findings. Erythrocyte ag gregation was highly significantly increased in the CRVO group when co mpared with the control group (P < 0.0001), as was the hematocrit leve l (P < 0.05). In addition, the proportion of patients with abnormal bl ood theologic tests was greater (50%) in the subgroup of patients who initially had nonischemic CRVO that worsened into an ischemic CRVO dur ing the follow-up. Conclusion: These data suggest that abnormal hemorh eologic findings could affect the pathogenesis of CRVO, and perhaps be predictive of an aggravation. The latter hypothesis needs to be confi rmed in a larger, prospective study.