Analysis of the effect of calcium ions on promoting the penetrability of riboflavin into the corneal stroma by iontophoresis.

ABSTRACT

PURPOSE: To investigate the effect of calcium ions on promoting the penetrability of riboflavin into the corneal stroma by iontophoresis and to analyse the possible mechanism. METHODS: Forty rabbits were divided into five groups randomly 0.1% riboflavin-balanced salt solution (BSS) by iontophoresis group, 0.1% riboflavin-saline solution by iontophoresis group, 0.1% riboflavin-zinc gluconate solution by iontophoresis group, 0.1% riboflavin-calcium gluconate solution by iontophoresis group and classical riboflavin instillation after corneal de-epithelialization as the control group. The riboflavin concentrations in corneal stroma were determined and compared by high-performance liquid chromatography (HPLC) after removing epithelium and endothelium. RESULTS: Iontophoretic delivery of a 0.1% riboflavin-calcium gluconate solution was the closest to the effect of classical de-epithelialization. The other solvents were unsufficient at enhancing the permeability of the riboflavin. CONCLUSION: Calcium ions can promote the penetrability of riboflavin into the corneal stroma by iontophoresis.