Comparative amperometry on ocular-surgery electrolytes in eye-splinter trauma from galvanized-steel electrochemistry

Abstract

Metal foreign bodies in the eye are commonly removed utilizing a surgical approach through the vitreous cavity, which requires a maintained ocular pressure by infusion of replacement “irrigation solution”, i.e., electrolyte. However, when in contact with aerated electrolyte, if the fragment comprises galvanized steel, the component metals can act as a bimetallic zinc/steel cell, thereby electrochemically generating injurious amounts of hydroxyl ion OH⁻. The effect on this electrochemical reaction of the compositions of the irrigation solutions in use, and of their analogues, has thus been investigated, to seek the least damaging. The inter-metallic current relates directly to the rate of the injurious reaction, hence amperometry has been the principal probe employed in our study. Establishing reproducible conditions of contact between electrolyte and the steel–zinc combination forms a major focus of the study, which is to attain amperometric reproducibility in the comparison of the electrolytes. Geometry-sensitive directed injection of test solution into a cell with pre-fixed separate steel and Zn electrodes achieved the desiderata. Besides potentiometry and amperometry, pH and buffering by the various test solutions, and the effects of surfactants, were also examined. Free-radical intermediates in the oxygen processes are further injurious suspects. Anaerobic conditions that would preclude both intermediates and OH⁻ are unfortunately damaging to the structures of the eye, so alternative surgical procedures are needed. Anti-corrosion aspects are considered.