Affiliations: Instituto Bioquímica e Quimica Fisiológica, Fac. Medicina Lisboa, Lisboa, Portugal | Clínica Universitária de Oftalmologia, Fac. Medicina Lisboa, Lisboa, Portugal
Note:  Address for correspondence: Luis Sargento, Inst. Bioquímica, Fac. Medicina Lisboa, Av Prof. Egas Moniz, 1600 Lisboa, Portugal. E‐mail: lsarg@ fml.fm.ul.pt.
Abstract: Sodium fluorescein angiography is a widely used technology in ophthalmology, which allows us to visualise the chorioretinal microcirculation. Previous reports showed a prolongation of the retinal circulation time along with erythrocyte hyperaggregation and a decrease of erythrocyte acetylcholinesterase activity and a possible interference with the erythrocyte’s membrane fluidity. The aim of the present work is to investigate the influence of sodium fluorescein on the hemorheological profile of a group of 23 non‐insulin dependent diabetes mellitus (NIDDM) patients undergoing routine retinal angiography. Thirty minutes after the endovenous administration of the fluorescein there was: (I) an increase of whole blood viscosity (p=0.015), erythrocyte elongation index (EEI, p<0.05), whole blood pH (p<0.001), methemoglobin (p<0.001) and carboxyhemoglobin (p<0.001) concentrations; (II) no variation of plasma osmolality and erythrocyte aggregation index (EAI); (III) a decrease of the erythrocyte acetylcholinesterase activity, p<001; (IV) no variation in membrane lipid fluidity, although 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) correlated directly with the EEI, while 1,4‐trimethyl‐phenyl‐1,3,5‐hexatriene (TMA‐DPH) and EAI correlated inversely, suggesting that the decreasing EEI (lower erythrocyte deformablity) might be associated with an increased rigidity of the external polar region and fluidification of the hydrophobic region of the erythrocyte membrane, with an increasing EAI. In conclusion, the endovenous administration of sodium fluorescein in NIDDM patients during the retinal angiography procedure interferes with the erythrocyte membrane and possibly with the microcirculatory blood flow.