Allergic ocular disorders: a spectrum of diseases.

Allergic eye disease is commonly encountered in clinical practice. The external eye is exposed to a host of environmental, cosmetic, and pharmacologic antigens. Although individual responses show a wide range of variability, a number of distinctive syndromes have emerged to define the spectrum of allergic eye disease. They consist of seasonal allergic conjunctivitis (SAC), perennial allergic conjunctivitis (PAC), atopic keratoconjunctivitis (AKC), vernal keratoconjunctivitis (VKC), giant papillary conjunctivitis (GPC), and contact allergies involving the conjunctiva.