Immune Mechanisms, Pathology, and Management of Allergic Ocular Diseases

Allergic eye diseases are mediated primarily by immunoglobulin E (IgE) and/or Th2 cells along with cytokines, chemokines, histamine, prostaglandins, and leukotrienes that participate in the immunopathogenesis and immunopathology. Dendritic cells initiate the immune response to allergens by processing and presenting them as peptides to naïve T cells, which in turn, develops into allergen-specific Th2 cells that play a crucial role in the allergic immune process via action of Th2-derived cytokines that induce B cells to become allergen-specific IgE-producing plasma cells. This chapter provides a comprehensive review of the current understanding of the immunopathogenesis and immunopathology of allergic eye diseases including allergic conjunctivitis, giant papillary conjunctivitis, atopic keratoconjunctivitis, and vernal keratoconjunctivitis. The immunopathological process is responsible for the clinical manifestations of allergic eye diseases as well as damage and remodeling of the ocular surface. Furthermore, the role of immune cells and mediators in allergic ocular surface inflammation will be discussed in great detail with particular focus on T cells, eosinophils, mast cells, histamine, cytokines, chemokines, and eosinophil-derived mediators. Finally, clinical management of allergic eye diseases with pharmacotherapy that targets cells and mediators of allergic eye diseases as well as potential future therapeutic directions such as potential adjunctive therapeutic benefits of resident ocular microbiome that modulate the ocular mucosal immunity will be discussed. The main objective of this chapter is to highlight the immunopathology of allergic eye disease with a view to focus interest in developing therapeutic agents that target cells and mediators of allergic immune response and consequential immunopathological processes.