Abnormalities in haemorheological factors and lipoprotein (a) in retinal vascular occlusion: implications for increased vascular risk.

BACKGROUND

The pathogenesis of retinal vascular occlusion (RVO), which includes patients with retinal vein or artery occlusions, may be associated with abnormalities of rheology and coagulation. These abnormalities have previously been linked with an increased risk of cardiovascular disease and stroke.

AIM, PATIENTS AND METHODS: To investigate changes in haemorheological factors (plasma viscosity, haematocrit, haemoglobin, white cell count (WCC), plasma fibrinogen (CLAUSS), soluble adhesion molecule P-selectin (associated with platelet activity and atherosclerosis; ELISA), von Willebrand factor (vWf, an index of endothelial dysfunction; ELISA), fibrin D-dimer (ELISA), lipoprotein(a) (Lp(a), immunoturbidometric assay) and serum lipids, we conducted a cross-sectional case-controlled study of 49 patients (37 men; mean age 66.9 years, SD 12.1 years) with RVO; 34 patients had retinal vein occlusion, whilst 15 had retinal artery occlusion. Their results were compared with those in 36 healthy controls (21 men; mean age 63.7 years, SD 14.8 years).

RESULTS

Patients with retinal vein occlusion and retinal artery occlusion had higher systolic and diastolic blood pressures compared with controls (both p < 0.0001). These patients also had significantly elevated levels of plasma viscosity, haematocrit, haemoglobin, plasma fibrinogen, PAI, fibrin D-dimer and serum Lp(a) compared with controls. Apart from a reduction in blood pressure, there were no significant differences in the indices measured in patients with retinal vein occlusion when levels measured during their first and second visits were compared. In patients with retinal artery occlusion mean plasma PAI levels were significantly lower at visit 2 compared with visit 1. Plasma viscosity was significantly correlated with fibrinogen (r = 0.63, p < 0.001), systolic blood pressure (r = 0.33, p = 0.03) and cholesterol (r = 0.32, p = 0.04), while P-selectin was correlated with Lp(a) levels (r = 0.38, p = 0.03).

CONCLUSION

This study suggests that abnormalities in haemorheological factors, fibrinogen and Lp(a) are present in patients with retinal vein occlusion and retinal artery occlusion. These abnormalities appear to persist even at follow-up examination 4-6 weeks later. Abnormalities in haemorheological factors, fibrinogen and Lp(a) may have a role in the pathogenesis of retinal vein occlusion and retinal artery occlusion, perhaps acting synergistically with clinical risk factors such as blood pressure. In addition, as haemorheological factors, fibrinogen and Lp(a) are associated with vascular disease, these findings in patients with RVO may potentially contribute to an increased risk of cardiovascular disease and stroke.