I answered your other post, but the eyedrop that has worked best for me is Patanol. It is a mast cell inhibitor. Mast cells are what release the histimine, so it works better than an antihistimine because it stops the reactio before it starts. Antihistimines just mop up all the histimine in your system.

When whatever pollen you are allergic too is really high in the air, using a simple eyewash kit to wash your eye out in the evening helps a lot too.