Purpose
Dry Eye Disease (DED) is still insufficiently understood because it is a complex alteration of the functional anatomy of the ocular surface. Current concepts are often oversimplified and a new realistic model is developed that reflects all relevant aspects.
Methods
. A NLM PubMed based review of the literature on DED was performed. Pathogenetic mechanisms were identified and arranged in a patho‐physiologic hierarchy of causative relations that reflects clinical findings but is independent of assumed ′importance′.
Results
Basic primary causative factors for DED are structural and functional alterations of the ocular surface integrity. This concerns a deficiency of (A) tear component SECRETION by the secretory elements and of (B) tear FILM FORMATION by the eye lids and blinking mechanism. Together this leads to the two main pathologies of (1) TEAR FILM DEFICIENCY and thus insufficient permanent wetting of the interpalpebral surface that causes (2) the well‐known SURFACE TISSUE DAMAGE that gives rise to signs and symptoms. Both pathologies are governed by several interacting secondary pathogenetic factors. Typical for the complex disease mechanism are self‐enforcing vicious circles ‐ in contrast to present over‐simplified models they do not necessarily depend on inflammation and there are in fact several, different, interacting vicious circles instead of just one. The disease process is influenced by an impairment of regulatory systems (innervation, endocrine system, immune system) of the body & by negative internal and external risk factors.
Conclusions
This new holistic dynamic concept on the pathophysiology DED incorporates long established as well as new mechanisms in the pathophysiological order. It is complex but not complicated ‐ intuitively understandable and suitable to assist basic scientist, patients, and clinical practitioner alike.