Hyperosmolar Tears Enhance Sensitivity of the Special Corneal Nerves to Ocular Surface Cooling: Possible Neural Basis for Cold-induced Dry Eye Pain

cold air“Tear hyperosmolarity is a ubiquitous feature of dry eye disease” according to the Aug. 25, 2014 Recently Accepted Papers Alert of Investigative Ophthalmology & Visual Science (IOVS). Harumitsu et al provide extremely interesting evidence in the manuscript “Hyperosmolar tears enhance sensitivity of the special corneal nerves to ocular surface cooling: possible neural basis for cold-induced dry eye pain”, where they evaluate high threshold cold sensitive plus dry-sensitive (HT-CT + DS) neurons in rats is normally excited by strong (>4°C) cooling of the cornea which, when applied to humans, evokes the sensation of discomfort in humans. The researchers sought to determine if these nociceptors of the cornea could be sensitized by hyperosmolar tears such that they are now activated by small cooing of the cornea. They looked at responses of single corneal neurons to cooling stimuli presented in the presence of hyperosmolar (350-800mOms NaCl) tears which we know causes evaporation/breakdown of the tear film leading to significant cooling of the ocular surface.

This is exciting as we are now getting down to the cellular response to what hyperosmolar tears do the cells and possibly why some patients have significant discomfort when their tear film breaks down. It may also help us understand why while diabetics have such a high incidence of dry eye disease (DED), but often have very low symptoms and neurotrophic damage is likely the culprit. This is another strong reason why patients having diabetes need to have tear osmolarity as well as a very thorough evaluation to determine if they do have DED.

Read their conclusions here: Hyperosmolar Tears Enhance Sensitivity of the Special Corneal Nerves

What Do We Do with the Information We Obtain from Tear Osmolarity Testing

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In Dr. Cynthia Matossian's third installment of 'In My Practice', she focuses on the process that occurs after she has obtained a patient's tear osmolarity data. From educating the patient, to treatment recommendations, Dr. Matossian elaborates on … [Continue reading]

Comparative Role of 20% Cord Blood Serum and 20% Autologous Serum in Dry Eye with Hansen’s Disease

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While we wait for more effective topical ophthalmic pharmaceutical drugs for the treatment of significant dry eye disease (DED) in patients that currently available prescription therapy is insufficient, we should not forget the importance of using … [Continue reading]

Rigel Dry Eye Drug Misses Endpoints in Phase 2


Well, another dry eye disease (DED) drug fails to meet endpoints. Rigel Pharmaceuticals Inc. announced its JAK/SYK inhibitor (R348) did not meet the primary or secondary endpoints in their Phase 2 clinical study. The endpoints were measured by … [Continue reading]

How to Implement Tear Osmolarity Testing in a Practice


It can be difficult to implement any new process into a busy ophthalmology practice. Dr. Cynthia Matossian of Matossian Eye Associates follows up her first feature article by discussing how she approaches introducing a new process into her practice; … [Continue reading]

The Matossian Eye Associates Tear Osmolarity Protocol


In part one of Dr. Cynthia Matossian's four part series, she discusses why and how tear osmolarity is an essential component when determining treatment plans for different types of patients including cataract consults and contact lens wearers. To … [Continue reading]

Ocular Surface Disease Index & Tear Osmolarity as Markers of Ocular Surface Dysfunction in Video Terminal Display Workers


Another great publication just out in the July issue of the American Journal of Opthalmology continues the focus on patients in the workplace having to deal with dry eye disease (DED). A few weeks ago we showed workers using video display terminals … [Continue reading]

Tear Osmolarity: the Key to Gauging Response to Dry Eye Disease Therapy


In this new article, Dr. Mitchell Jackson discusses why he believes measuring a patient's tear osmolarity is the key to gauging their response to Dry Eye Disease therapies. Dr. Jackson further elaborates on how continuously monitoring this response … [Continue reading]

Understanding New Insights on Patient Experiences After Lasik

Laser Eye Surgery

Have you noticed that patients considering refractive surgery (PRK or LASIK) or intraocular lenses (IOL) have huge expectations and very little concern about postop complications? As well, what are you doing these days in preoperative counseling and … [Continue reading]

Sleep Deprivation Reduces Tear Secretion and Impairs the Tear Film

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Sleep deprivation (SD) can cause a number of issues with our body not just physically but also physiologically. A new publication in the latest IOVS Journal Volume 55 titled "Sleep Deprivation Reduces Tear Secretion and Impairs the Tear Film” by … [Continue reading]