OVERVIEW on ...
WHAT IS DRY EYE DISEASE ?
Dry Eye Disease is a complex, typically chronic, dysregulation of the functional anatomy of the ocular surface including the tear film that typically leads to symptoms of dryness, visual disturbance, ocular irritation and pain - it can be amplified by self-enforcing vicious circles that are prominently driven by inflammatory pathways and may eventually lead to a progressive destruction of the ocular surface.
Some clinical images of patients with Dry Eye Disease - the disease severity increases from left to right including increasing alterations of the lid margin with pouting of Meibomian gland orifices, inflammation, lid margin rounding and irregularity, with loss of eye lashes
Dry Eye Disease is a Prototypic Ocular Surface Disease
Dry Eye Disease is a prototypic Ocular Surface Disease because it is based on a deficiency of Moisture – which is the most basic function of the Ocular Surface.
Moisture is the pre-requisite for Ocular Surface Health and thus for the establishment and maintenance of vision ... as explained in the Ocular Surface Section - for more details please see there.
Dry Eye Disease is a PROTOTYPIC ocular surface disease because:
it is based on an IMPAIRMENT of the most basic function of the Ocular Surface - which is the maintenance of MOISTURE
it can therefore be induced by a variety of factors and
it can affect all parts of the ocular surface unit
independent of the starting point …
... eventually,
the LACK of Moisture leads to onset of the Signs and Symptoms of Dry Eye Disease
which is a chronic condition and typically produces a progressive destruction of the ocular surface
Moisture is the pre-requisite for Ocular Surface Health and thus for the establishment and maintenance of vision.
It is only guaranteed ...
as long as the basic anatomical integrity of the tissues and organs is provided that constitute the Anatomical Unit
and
as long as the functional interaction of the organs is achieved by the involved regulatory systems that, together with tissue integrity, constitute the Functional Unit (for details please see there).
Dry Eye Disease is non-specific in the sense that it is not specifically due to any particular infection or allergic or other specific affection of the ocular surface.
Some general systemic risk factors such as age, sex hormone levels or skin diseases increase the risk of Dry Eye Disease. Environmental factors can also play a significant role.
Dry Eye – a Syndrome or a Disease ?
This ´promiscuous´ nature of Dry Eye, as explained above, may be a reason why Dry Eye has long been considered as a syndrome, which is a loosely related bunch of symptoms with unclear stringent etiology, rather than a disease with specific etiology.
However patho-physiologically, Dry Eye is based on a failure of the most essential functional complex - the provision of moisture - and therefore it is influenced by many factors - which may give the impression of a mere ´syndrome´.
Sjögren´s SYNDROME, the auto-immune inflammation of the lacrimal gland and other glands in the body, was also long time termed as a ´Syndrome´. Sjögren´sis probably the best known, but still a practically rare, cause for aqueous-deficient Dry Eye. Sjögren´s Syndrome has meanwhile been ´officially promoted´ to a "Disease" and Dry Eye ´Disease´ has also become an established term.
In both of theses cases the scientific knowledge on the pathophysiology and therapy has greatly increased in recent years due to continuing and even increasing research efforts which supports many approaches for an evidence based therapy !