Aim: To investigate the effect of low-density lipoprotein (LDL) apheresis on ocular microcirculation in patients with hypercholesterolaemia. Methods: Six patients with hypercholesterolaemia were included in this study. The diameter of retinal vessels was measured continuously with the retinal vessel analyser before and after LDL apheresis. After baseline assessment a monochromatic luminance flicker was applied to evoke retinal vasodilation. Flicker response was then analysed 50, 70 and 120 s after baseline measurement. In addition, cholesterol, high-density lipoprotein, LDL and triglyceride levels were obtained to find a possible correlation between changes in retinal vessel diameter and lipid metabolism before and after apheresis. Results: The mean diameter of the arterioles at baseline was 107.6±2.1 μm and the mean diameter of the venules at baseline was 132.8±3.2 μm. The diameter of the arterioles after apheresis increased to 111.2±2.3 μm after 50 s, 113.2±2.6 μm after 70 s and 113.7±2.6 μm after 120 s, showing a trend to statistical significance at all time points (p=0.046, p=0.028 and p=0.028, respectively). The mean diameter of the venules after apheresis increased to 138.8±5.9 μm after 50 s, 139.8±6.3 μm after 70 s and 141.2±6.0 μm after 120 s, showing a trend to statistical significance at all time points (all p=0.028). Conclusions: Changes in retinal vascular diameter seem to be associated with the systemic effect of a single LDL apheresis. Vasodilatation of the arterioles and the venules improved after LDL apheresis, indicating an improvement of ocular perfusion in patients with hypercholesterolaemia.