Effects of topically applied occular decongestant and antihistamine.

In two independent studies including 25 subjects each, naphazoline caused significant whitening (but did not prevent itching) in the histamine-induced red, itchy eye. Antazoline inhibited itching (but not redness) to a significant degree in the same model. The combination of naphazoline and antazoline produced significant whitening and inhibition of itching in all eyes challenged by histamine. The combination of the two drugs was more effective than either component alone in preventing redness. The antihistamine and combination of antihistamine/vasoconstrictor were equally effective in arresting itching.