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ABSTRACT.Purpose: To evaluate the ocular blood flow velocities and haemorheological parameters in patients with primary open-angle glaucoma (POAG), exfoliative glaucoma (XFG) and exfoliation syndrome (XFS) and to compare their results with those of healthy controls. Methods: Twenty-five patients with POAG (group 1), 25 patients with XFG (group 2), 25 patients with XFS (group 3) and 25 healthy controls (group 4) were included in the study. Ocular blood flow velocities of ophthalmic artery (OA), central retinal artery (CRA) and short posterior ciliary arteries (SPCAs) were measured using colour Doppler imaging (CDI). Haemorheological parameters (erythrocyte elongation and aggregation index, aggregation amplitude, aggregation half-life, plasma viscosity, haematocrit) were measured in venous blood samples of all patients. Results: The peak systolic velocity (PSV) and end-diastolic velocity (EDV) values were lower and resistive indices (RI) were higher for the OA, CRA and SPCA of glaucomatous (groups 1 and 2) patients compared with those of controls (group 4) (PSV: OA, 40.4 ± 11.3 versus 52.6 ± 12.8 cm ⁄ second, p < 0.001; CRA, 12.9 ± 2.9 versus 15.3 ± 4.2 cm ⁄ second, p = 0.02; SPCA, 21.7 ± 6.6 versus 26.6 ± 8.3 cm ⁄ second, p = 0.013) (EDV: OA, 10.3 ± 4.3 versus 14.2 ± 5.1 cm ⁄ second, p < 0.001; CRA, 3.7 ± 1.1 versus 4.5 ± 1.3 cm ⁄ second, p = 0.025; SPCA, 5.2 ± 1.8 versus 7.7 ± 3.2 cm ⁄ second, p = 0.001) (RI: OA, 0.75 ± 0.05 versus 0.66 ± 0.07, p < 0.001; CRA, 0.73 ± 0.08 versus 0.68 ± 0.10, p = 0.223; SPCA, 0.70 ± 0.10 versus 0.63 ± 0.11, p = 0.004). There were no statistically significant differences between the haemorheological parameters of glaucomatous and non-glaucomatous patients. The reduction in ocular blood flow velocities in groups 1, 2 and 3 were not associated with changes in haemorheological parameters. Conclusion: Our results suggest that impairment of the retrobulbar blood flow in POAG and XFG is not associated with alterations in haemorheological parameters.

Oxidative stress decreases the deformability of erythrocytes. Anti-oxidant measures may alleviate, pro-oxidative damage may augment this decrease. Melatonin is reported to exert both anti-oxidant and pro-oxidant properties on erythrocytes. The aim of the present study was to evaluate the effects of melatonin on erythrocyte deformability under oxidative stress conditions induced by the combination of hydrogen peroxide (20 mM) and sodium azide (100 µM). Erythrocyte suspensions were incubated for 10 min with melatonin (1-1000 µM) prior to oxidative stress. Erythrocyte deformability was measured by Laser-assisted Optical Rotational Cell Analyzer (LORCA). Lipid peroxidation was determined via malondialdehyde (MDA) measurements by HPLC. Melatonin alone did not change erythrocyte deformability. Oxidative stress alone decreased the deformability of erythrocytes by 25.8 ± 3.1% (P < 0.05). Melatonin pre-treatment augmented the decrease in erythrocyte deformability but prevented lipid peroxidation. Melatonin (1 µM) did not cause any additional effect on erythrocyte deformability. Higher concentrations (10-1000 µM) further decreased deformability (P < 0.05). Erythrocytes exposed to oxidative stress had MDA levels of 116.3 ± 14.3 µmol/g Hb. Melatonin (1 µM) slightly increased MDA levels, but 1000 µM melatonin reduced it by 35% (P < 0.05). These findings indicate that melatonin exerts antioxidant effect on lipids. Deterioration of erythrocyte deformability may be due to a separate pro-oxidative action on proteins.