Penetration of dissolved material through the cornea is believed to be a function primarily of phase solubility. The epithelium and the endothelium of the cornea are barriers to substances that are not soluble in fats, while the stroma similarly is a barrier to substances not soluble in water. Weak electrolytes require special consideration not only because they include the important group of alkaloids used clinically but because their solubilities in fat and water vary according to their degree of dissociation. In the present paper, studies will be reported on the effect of variations in this dissociation on the penetration of weak electrolytes through the cornea.
Within a range that is characteristic for each substance, weak bases become progressively dissociated with low hydrogen ion concentrations and weak acids with high hydrogen ion concentrations. In the undissociated form (free base) most weak organic electrolytes are fat soluble and variously water soluble, while