Eye allergies are no different than allergies that affect your sinuses, nose or lungs. When an allergen comes in contact with your eyes, your body releases histamine - a chemical produced in reaction to a substance that the immune system can't tolerate. Special cells called mast cells make histamine. These cells are present throughout the body but are highly concentrated in the eyes.

Ocular allergens tend to be airborne (as are most other allergens). The most frequent allergic triggers include pollen, pet hair or dander and dust.

Allergies are a primary cause of conjunctivitis, also known as "pink eye," an inflammation of the conjunctiva (the membrane lining under the eyelids). Common symptoms of allergic conjunctivitis are redness and itching under the eyelid, excessive watering and swelling of the eyeball. Common symptoms of conjunctivitis associated with infection are:

Feeling that eyelids are glued shut upon waking
Sensitivity to light
Pus on the surface of the eye
Burning sensation

If you have ocular allergies or any other kind of allergic disease, the most effective treatment is prevention: try to avoid the allergens that trigger symptoms, such as pollen.

When ocular allergies can't be controlled, there are several medications that may help relieve symptoms. Most of these treatments come in a topical form - such as eye drops or an ointment.

Eye drops can help by physically washing away allergens and moistening the eye, which can become dry and red when irritated. Eye drops that contain medications to help reduce allergy symptoms also are available.

You may benefit from immunotherapy, in which an allergy specialist injects you with small amounts of the allergen to help you gradually build up immunity to it.