An introduction to ocular immunology.

The interdigitated mechanisms by which an organism protects itself from microbiological infection have been collectively termed the immune system. We have been given the impression that the eye is "immunologically privileged" because the cornea accepts allografts. Despite the common success of corneal grafts, however, the ocular surface must perpetually combat infection with an array of immunological machinery. This includes mechanical protection as well as elements of humoral, cellular, adaptive, and innate immunity in the tears, conjunctiva, and even the cornea. Optometrists who fit contact lenses strive to help patients achieve safe contact lens wear by minimizing the risk of corneal infection and overaction (hypersensitivity) of the immune system in response to contact lenses and related care products. An understanding of immunology in general and the ocular response(s) in particular enables the clinician to provide a broader scope of care.