The tear film consists of a gel of :
a) Aqueous (salty water) produced mainly by the lacrimal gland just above the upper outer eye lid.
b) An inner layer of mucin produced mainly by the conjunctiva (the transparent lining that covers the white part of the eye and the inner lining of the eyelids).
c) A thin outer layer of oil/ lipid that slows the evaporation of the tears. This layer is produced from the oil glands of the eye lid (meibomian glands), just behind the lashes.
For the surface cells of the eye (epithelium) to remain healthy they must be covered by the tear film at all times. So the tear film needs to be stable enough to last between each of your blinks, approximately 15 seconds.
You will get dry eye symptoms if :
a) Any one or all of the components of the tears (most often the oil layer) is substandard and your tears evaporate before the next blink.
b) your eye lids don’t close properly
c) the environment you are in increases evaporation (e.g. air conditioning, central heating) or slows your blink rate (e.g. reading, computer use)
Dry eye is predominantly about increased tear evaporation.
Most “Dry Eye” occurs due to too rapid evaporation of the tears.
Some individuals do have a true lack of tear production from the lacrimal gland. This type of Dry Eye can be associated with hormonal changes at menopause, some medications prescribed for other general health problems and autoimmune disorders, such as Sjogren’s syndrome and rheumatoid arthritis.
It’s a vicious cycle:
When surface epithelial cells are damaged due to dehydration, they set off an immune response. Unfortunately, this response alters the mucin production from the ocular surface. This results in a thinner, less stable tear film which will evaporate even faster, leading to more ocular surface cell damage and more inflammation, thus setting up a vicious cycle.
Unfortunately , there is no cure for proper dry eye , just as there is no cure for other chronic conditions like diabetes or dandruff. Treating dry eye involves treating all the components of the tear film on an ongoing basis.
Poor Oil Layer (meibomitis):
Warm compresses, digital expression of the meibomian glands and cleaning the eye lid margins can reduce eyelid bacteria that disturb the oil layer.
Antibacterial medical honey applied to the eyelid margins can assist in the management of inflamed Meibomian glands (meibomitis). Lipid containing artificial tear supplements may be of benefit in meibomian gland dysfunction. Increasing your Omega 3 consumption can improve the oil layer of your tears.
Artificial tears supplements are essential for treating this aspect of dry eye. Non-preserved supplements are preferable in more severe cases of tear deficiency.
The puncta, which allow tears to drain from the eye down into the nose, can be plugged with punctal plugs. This increases the volume of tears but reduces tear turnover and so can exacerbate ocular surface inflammation.
Dietary Omega 3 supplements can increase tear secretion and reduce inflammation.
The use of good lid hygiene, non-preserved lubricating eye drops, antibacterial medical honey and anti-inflammatory, eye treatments such as the short term use of topical surface acting eye steroids, can regenerate the conjunctival goblet cells (mucin producing surface cells)
Incomplete Lid Closure/Blinking:
If you sleep with your eyes partly open, you will need to apply a lubricating eye ointment or viscous (thick) lubricating eye drop before sleep. If your eyelids don’t meet when you blink, you can practice blinking completely for a few minutes a day by more forceful blinking.