Pathogenesis of allergic conjunctivitis and trends in its treatment

Allergic conjunctivitis is characterized by specific immunologic responses known as type 1 hypersensitivity, resulting in corneal and conjunctival inflammation. Histamine plays an important role in the pathophysiologic mechanism of allergic conjunctivitis. Five subtypes of allergic conjunctivitis have been defined according to specific signs and symptoms: Seasonal allergic conjunctivitis, perennial allergic conjunctivitis, vernal keratoconjunctivitis, atopic keratoconjunctivitis and giant papillary conjunctivitis. Above all, avoidance of the offending antigen is the primary behavioral modification used to treat all types of allergic conjunctivitis. However, this may be difficult for practical reasons; therefore, a range of medical treatment options, such as topical antihistamines, mast cell stabilizers, non-steroidal anti-inflammatory drugs, and corticosteroids are prescribed in clinical practice.