Elemental composition of aqueous humour and blood serum at various levels of intraocular pressure

Abstract

Aim - to conduct a comparative study of element concentrations in the aqueous humour of human eye and blood serum at various levels of intraocular pressure (IOP). Material and methods. The chemical composition of biological fluids was studied in two equal groups (33 patients/33 eyes each): group 1 - primary open-angle glaucoma (POAG) with decompensated IOP and group 2 - normal IOP (the controls). Sampling of the aqueous humour and blood was done during surgical procedures, namely, penetrating glaucoma surgery (group 1) and cataract phacoemulsification (group 2). Blood was taken from the cubital vein and centrifuged to obtain the supernatant for further analysis. The samples were studied with Zeiss EVO LS10 scanning electron microscope (SEM) equipped with Oxford X-Max50 energy dispersive spectrometer. Results. In both groups, regardless of the IOP level, Na and K concentrations were found to be constantly higher in the aqueous humour than the blood serum. The ratio of Na concentrations in the aqueous humour and serum (measured in mmol/l) was 1.51/1.30 at normal IOP and 1.49/1.31 at decompensated IOP. The ratio of K concentrations was 0.11/0.03 and 0.12/0.03, respectively. Concentrations of N and S in the aqueous humour were higher in the group with decompensated IOP. Conclusion. Regardless of the IOP level, Na and K concentrations were found to be constantly higher in the aqueous humour than the blood serum. IOP elevation was accompanied by an increase in N and S concentrations in the aqueous humour.