Pataday Once Daily Eye Allergy Itch Relief Eye Drops itchy Eyes? Meet the Invisible Enemies. Did you know there are thousands of allergens in every cubic yard of air? Pollen, ragweed, and grass are the triggers we might think of first. But you don't have to set foot outdoors to have your day ruined by itchy allergy eyes. Pet dander and animal hair are among the most common indoor allergens. That's why there's Pataday. Pataday is made to relieve the itch caused by these everyday culprits—both indoor and out.