An allergic reaction that affects the conjunctiva, a clear layer of skin overlying the eyes, is commonly referred to as allergic conjunctivitis.
Allergic conjunctivitis is divided into several major subtypes, but the most common subtypes are seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC). SAC and PAC are triggered by an immune reaction involving a sensitized individual and an allergen. Simply stated, this means that if you are allergic to a particular substance and then come into contact with it, you experience an allergic reaction (eg, itching, sneezing).
Although it frequently occurs, allergic conjunctivitis is most commonly seen in areas with high seasonal allergens. Common allergens include pollen, grass, weeds, dust and pet dander.