Dry Eye Syndrome is a multifactorial disease, meaning that many factors can contribute to the disease and the symptoms we experience. The multifactorial nature of the disease and the terms used to describe various conditions contribute to confusion and misunderstanding of the condition.
Overview of Dry Eye Syndrome
When we discuss Dry Eye Syndrome, or Dry Eye for short, usually this means insufficient production of aqueous tears by the lacrimal gland. This form of the disease is also known as aqueous deficient dry eye, aqueous deficiency, or aqueous tear deficiency.
In addition, Dry Eye Syndrome is frequently used as an umbrella term to cover many other related diseases, such as evaporative dry eye, an insufficient or poor production of meibum. Blepharitis, inflammation of the eye lids, is frequently a co-morbid disease that can contribute to evaporative dry eye. One type of blepharitis, posterior blepharitis, is also frequently referred to as meibomian gland dysfunction (MGD). Although overlapping, these are different diseases (Nichols et al., 2011). All of these conditions that can co-exist, co-morbid conditions or co-morbidities, make discussion of Dry Eye not only confusing and difficult to understand, but also difficult to diagnose and treat.
The list of co-morbid conditions that contribute to Dry Eye is lengthy. For example, lagophthalmos, incomplete closing of the eye, and entropion, inward turning of the eye lids, are just two of many others.
Adding to the complexity of diagnosing and treating Dry Eye, there are numerous other diseases and conditions that can cause the same symptoms as Dry Eye. Treatments for these diseases may be very different or sometimes the same as the treatments prescribed for Dry Eye e.g.: lubricating drops, topical antibiotics, or corticosteroids.
The International Workshop on Meibomian Gland Dysfunction: Executive Summary
Nichols, K., Foulks, G., Bron, A., Glasgow, B., Dogru, M., Tsubota, K., Lemp, M., Sullivan, D.
Investigative Ophthalmology & Visual Science
2011 Mar 30;52(4):1922-9. doi: 10.1167/iovs.10-6997a.
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