Allergy and Immune-Mediated Tissue Injury
The immune system serves a protective role in our defense against pathogens. However, the immune response may sometimes be misdirected or exaggerated in a way that results in pathology. Such inappropriate responses are termed as "hypersensitivity reactions." The purpose of this chapter is to offer an informed insight on the four classic types of hypersensitivity reactions with particular focus on their implications in ophthalmology. Hypersensitivity reactions can be a common cause of a variety of burdensome and even fatal disorders. Our understanding of the complexities behind hypersensitivity responses continues to grow. The mechanisms that entail the development of the increasingly prevalent allergic disease are clearer now than they were even a decade ago. Recent developments have identified previously un-implicated components including distinct inflammatory cells and pathways in the development of allergy and other hypersensitive reactions. Such findings have allowed the identification of novel agents that target these factors and permit better control of these diseases. Physicians are now able to choose from a variety of therapeutic options and tailor therapy to the disease at hand. Such a specific approach can result in better outcomes and can limit unwelcome side effects. This is particularly important for the ophthalmologist considering the fragile nature of ocular tissues.
