Figure 1.

Principles for animal dry eye modeling. A schematic showing approaches to developing animal dry eye models, including major methods used in recently published studies, as described in this review. Lacrimal glands excision, neural pathway blocking, and autoimmune disease models, including Sjögren's syndrome and systemic lupus erythematosus, have been developed by targeting the lacrimal gland. These result in an aqueous deficiency in the tear film. Conjunctival goblet cell damage can result in mucin deficiency in the tear film. Further, chemicals, drugs, and radiation hazards mainly cause corneal epithelium damage. Some gene-modified mice can present with dysfunction or direct damage of the Meibomian glands, resulting in lipid deficiency in the tear film. Environmental stress due to changing humidity, controlling airflow, and/or introduction of air pollution particulate matter, could also be significant in animal dry eye modeling.