Eye allergy is usually caused by allergen. If you are outdoor, the allergen may be grass, tree and weed pollens which may trigger your eye allergies. If you are indoor, the allergen can be pet hair, dust mites and molds which can also be the triggers for eye allergy.
The most common outdoor airborne allergens are grass, tree and weed pollens. People who are sensitive to these allergens suffer from seasonal allergic conjunctivitis, the most common type of eye allergy.
Pet hair or dander, dust mites and molds are the most common indoor allergens. These indoor allergens can trigger symptoms for some people throughout the year, resulting in perennial allergic conjunctivitis.