Direct action of triggers on the target organ may cause vasodilation, exudation, hypersecretion and nerve endings stimulation without participation of mast cells and basophils. Non IgE-mediated release of mediators from mast cells and basophils may explain how triggers other than allergens can induce pseudo-allergic reactions. IgE-mediated triggering of mast cells and basophils is not confined - in the eye too - to an immediate reaction, but represents the starting point for a progression to a late-phase reaction with the participation of a network of several cells and mediators. Inflammatory changes associated with late-phase reaction in the eye represent the pathophysiological basis for a non-specific hyperreactivity to various triggers.