How Tear Hyperosmolarity and Other Factors Cause Dry Eye

| Posted on March 25, 2016

One of the primary causes of chronic dry eye disease is tear hyperosmolarity. The Definition and Classification Subcommittee of the 2007 International Dry Eye Workshop defines dry eye disease as “a multifactorial disease of the tears and ocular surface that results in symptoms of discomfort, visual disturbance, and tear film instability with potential damage to the ocular surface. It is accompanied by increased osmolarity of the tear film and inflammation of the ocular surface.” 

Given its mention in the official definition of dry eye, tear hyperosmolarity is clearly an underlying factor in the development of the disease. In basic terms, tear osmolarity can be defined as the saltiness of the tears. According to Tearlab.com, “as osmolarity in your tears increases ocular surface cells become damaged,” leading to an increased likelihood of developing dry eye disease. How does this happen?

Normal tear production is controlled by the lacrimal functional unit, which uses a number of biological mechanisms to secrete “the three major components of the tear film (mucin, aqueous, and lipid)…onto the ocular surface in a coordinated fashion.” Tear hyperosmolarity results from a reduction in the lacrimal functional unit’s normal production of tears. 

Tear hyperosmolarity “arises as a result of water evaporation from the exposed ocular surface, in situations of a low aqueous tear flow and/or as a result of excessive evaporation.” When this occurs, the surface of the epithelium (the outer tissue layer of the eye’s surface) is damaged by a number of resulting factors, leading to cell death and tear film instability. As an unfortunately cyclical result, the tear film instability causes further hyperosmolarity, exacerbating ocular surface damage and potentially causing chronic dry eye disease.

Preventing tear hyperosmolarity as a means to reduce the risk of developing chronic dry eye is still a subject of ongoing research. According to this article found on theocularsurfacejournal.com, “recent attempts to counteract tear hyperosmolarity…have included osmoprotectants, small organic molecules that are used in many cell types throughout the natural world to restore cell volume and stabilize protein function.” This treatment may protect ocular cells from destruction due to hyperosmolarity, thus saving the eye from the brutal cycle of tear film instability described above.

To learn more about Dry Eye and our unique line of natural Eye Care Products, click here.


Share on facebook
Share on twitter
Share on pinterest

Related Articles

An outdated contact lens or eyeglass prescription is not always the cause of blurred vision. While an annual visit to your eye doctor to check your prescription is never a bad idea, you might want to investigate some of the other common causes of blurred vision in your quest for clearer vision. Your cloudy vision may be your eyes’ way of telling you they want a little TLC.

If you are 65 or older, you may already have symptoms of dry eye disease or notice a decline in your vision. Many people choose cataract surgery to improve age-related changes in vision. Cataract surgery is the most commonly performed surgery in medicine. Whether or not cataract surgery is in your future, beginning a regular eye hygiene routine now can improve your overall eye health and comfort both before and after surgery.

Sign up for the Bruder eye care newsletter

The latest in eyelid & lash hygiene plus sales and eye care tips! Select if you’re a consumer or eye care professional to tailor content specifically to your needs.