Overview, Dry Eyes:

Dry eyes, often referred to as Dry Eye Syndrome, is the most frequent patient complaint to eye doctors. About 15% of the population in all groups experience varying degrees of dry eye syndromes. Like most eye conditions, Dry Eye Syndrome is often related to health conditions in the rest of the body. It is commonly associated with dryness of other mucous membranes, interior body surfaces such as joints and brittle nails. It can also be a sign of digestive imbalances or of more serious systemic autoimmune diseases, such as rheumatoid arthritis, Sjogrens syndrome or lupus erthematosus.

The proper production of tears basically takes place at three layers:

• The Mucus Layer – is the closest layer to the corneal epithelium. It is produced by the conjunctival goblet cells, and is absorbed by the corneal surface glycoproteins, creating a hydrophilic corneal surface.
• The Aqueous Layer - is between the Mucous and Lipid Layers, and comprises 90% of the tear film’s thickness. It is secreted by the lacrimal gland and incorporates all water-soluble components of the tear film (slightly alkaline at pH of 7.4).
• The Lipid Layer - is the most superficial layer. The Meibomiam glands produce it with minor contribution from glands of Zeis and Moll. The secretion is a sebaceous material that is fluid at body temperature, and retards evaporation of the aqueous layer and lowers surface tension thereby allowing tear-film to mould itself to the eye’s surface.
• The Blink renews the tear film by delivering aqueous and lipid to tear film and sweeping away debris. The normal blink interval is every 5 seconds. Tear film is typically stable for about 10 seconds

Symptoms:

The typical symptoms include dryness, grittiness, irritation, difficulty reading for long periods of time, burning and even the seeming contradiction of excessive tearing or watering.