What Is Chronic Dry Eye Syndrome?
Chronic dry eye syndrome is an inflammatory condition of the conjunctiva with inadequate tear production or distribution over the eye surface. It is characterized by surface damage to the conjunctiva, giving the appearance of redness.
This complex condition involves the lacrimal glands, eyelids, and tear film, as well as a variety of eye surface tissues, including epithelial, inflammatory, immune, and goblet cells.1
Q: What is the conjunctiva?
A: The conjunctiva is the mucous membrane that lines the inside of the eyelids and covers the eyeball surface, also called the white of eye. The conjunctiva has a rich blood supply that can quickly bring microbe fighting cells to prevent invasion and overcome infection.
While infection and inflammation go hand-in-hand, they are not the cause of, but may result from, chronic dry eyes.
Dry eye syndrome develops from poor health of the conjunctiva that is associated with inadequate nutrition and poor quality of the tears that steadily lubricate the eye surface. These tears are called the tear film and are not the same as tears produced when crying or that result from irritating substances such as onions. Blinking spreads the tears that protect the surface from drying and flushes away unwanted matter.
The tear film is made up of three layers: mucous layer produced by goblet cells in the conjunctiva, aqueous (water) layer produced by the lacrimal glands, and lipid (fat) layer produced by the meibomian glands in the eyelids. Dysfunction of any of these layers impairs the the tear film. Without an adequate tear film the conjunctiva becomes dry and inflamed.
When the meibomian glands fail to produce sufficient lipid that is clear and fluid but rather cloudy and thick, the condition is called meibomian gland dysfunction (MGD). The main cause of MGD is hyperkeratinization (thickening of the glands) and its related pathogenesis (for example, ductal dilatation and acinar atrophy). Other disorders such as atopy, pemphigoid acne, rosacea, and seborrhea are related to MGD and may result in a chronic inflammation of the eye surface.2
MGD is “the most underrecognized, underappreciated and undertreated disease in ophthalmic care. It is so common as to be taken as ‘normal’ in many clinical practices,” according to Joseph Tauber, MD, an anterior segment subspecialist and refractive surgeon in Kansas City, Mo.3
Untreated dry eye progresses to xerophthalmia, a condition of extreme drying and thickening of the conjunctiva characterized by hazy, dry cornea. Other causes of dry eye, beside celiac disease, include certain systemic conditions such as Sjogren’s syndrome, an autoimmune disease.
What Is Chronic Dry Eye Syndrome In Celiac Disease and/or Gluten Sensitivity?
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Liu A, Ji J. Omega-3 essential fatty acids therapy for dry eye syndrome: a meta-analysis of randomized controlled studies. Med Sci Monit. 2014 Sep 6;20:1583-9. doi: 10.12659/MSM.891364. ↩
Oleñik A, Jiménez-Alfaro I, Alejandre-Alba N, Mahillo-Fernández I. A randomized, double-masked study to evaluate the effect of omega-3 fatty acids supplementation in meibomian gland dysfunction. Clin Interv Aging. 2013;8:1133-8. doi: 10.2147/CIA.S48955. Epub 2013 Aug 30. ↩
Rethinking Meibomian Gland Dysfunction: How to Spot It, Stage It and Treat It. Linda Roach, PhD. OPHTHALMIC PEARLS. ↩