Understanding the immunology of the ocular surface and its relevance to clinical practice.

The immunology of the ocular surface has an important role in maintaining homeostasis and in the etiopathogenesis of a number of diseases when dysregulated. This can result in damage to the cornea and ocular surface and loss of clarity and vision. As the entire ocular surface is linked via its epithelium, vascular supply, and innervation, changes across one aspect have tangible effects on the other. Immune cells residing on the ocular surface and those that traffic across the ocular surface interact with the structural tissues to release molecular factors and result in tissue response and disease. Studies in animal models and in vitro experiments along with in vivo studies on the human ocular surface have given newer insights with closer representation of actual health and disease. Some of the diseases which have been found to have a strong immunological basis include dry eye disease (DED) and Sjogren's syndrome, keratoconus, corneal graft rejection, autoimmune conditions such as peripheral ulcerative keratitis, and Stevens-Johnson syndrome. The ocular surface immunology has unique patterns and signatures across different diseases. These give us an opportunity to understand the diseases better find newer targets for therapy and an opportunity to reduce visual morbidity. Clinically, we envisage a shift from steroids and broad action immunomodulators toward target specific drugs making personalized medicine and customized therapy the way forward.