The eye is a sensory organ exposed to the environment and protected by a mucosal tissue barrier. 

1. While it shares a number of features with other mucosal tissues, the ocular mucosal system, composed of the conjunctiva, Meibomian glands, and lacrimal glands, is specialized to address the unique needs of (a) lubrication and (b) host defense of the ocular surface. 

Most challenges, physical and immunological, to the homeostasis of the eye fall into those several types. 

1. Dry eye, a dysfunction of the lacrimal glands and/or Meibomian glands, which can both cause, or arise from, sensory defects, including those caused by corneal herpes virus infection, serve as examples of these perturbations and will be discussed ahead. To preserve vision, dense neuronal and immune networks sense various stimuli and orchestrate responses, which must be tightly controlled to provide protection, while simultaneously minimizing collateral damage. 

2. All this happens against the backdrop of, and can be modified by, the microorganisms that colonize the ocular mucosa long-term, or that are transient passengers introduced from the environment. 

 Below is depicted the cellular interactions.  Image credit see link below.

The immune response in dry eye disease and the vicious cycle of inflammation

For the list of eye diseases: Fightforsight