Is dry eye getting on your nerves?
When your eyes lose too much moisture too quickly the natural balance of your ocular environment becomes compromised. This is essentially what dry eye is and it triggers a series of physiological changes which results in symptoms of discomfort and visual disturbances. Your tears become more concentrated, or saltier, which triggers an inflammatory response involving the release of histamine – itchy!
All the sensations experienced are as a direct result of nervous stimulation due to the loss of the protective moisture layer exposing delicate nerve endings.
Literally getting on your nerves
The transparent layer which covers the iris and pupil (the cornea) is one of the most nerve dense areas of the body. These nerves include mechanical, chemical and thermal receptors. Close to the surface they are activated by a variety of stimuli such as tear loss or inflammation – the result is those irritating dry eye symptoms. To avoid this ocular discomfort and to keep the surface healthy the protective tear-film needs to be maintained.
Dry eye can lead to nerve damage
Prolonged loss of tear quantity and quality can result in damage to the surface of the eye, including nerve damage. Researchers believe that the damage of ocular surface nerves, which control tear production and secretion as well as blinking, can also be a cause of dry eye. There is published research which indicates that dry eye sufferers have a decrease in the numbers of nerves present in the cornea.
This nerve dysfunction might help explain the long-time challenge faced by eye care professionals in that the signs of dry eye (reduced tear volume, damage to the eye surface, increased tear saltiness) do not always directly link to the symptoms (or most challengingly the lack of symptoms!) being experienced by the dry eye sufferer. This is one of the reasons why diagnosis is not always straight forward.
How do your eyes feel?
How sufferers go about describing these symptoms can vary significantly. Some symptoms are visual and relate to the disruption to the smooth optical surface created by our tears which is needed for sharp vision. However, most symptoms are as a result of stimulation of the range of nerve endings found at the eyes surface.
This list of symptoms below is not exhaustive, and each of these symptoms can also range from mild to severe. Are your symptoms included here?
What can be done to help?
The message is clear and fortunately there is plenty of help available. The first step is to get the advice of an independent eye care professional with a special interest in dry eye. They will diagnose your particular type of dry eye and prescribe a management plan to get the symptoms under-control. This might involve the recommendation of a preservative-free dry eye drop to protect the compromised delicate surface of the eye along with a combination of heat therapy and eye lid cleansing.
A word of caution
Unfortunately dry eye will not go away, it is a chronic and progressive disease. This means that if you ignore it then the signs and symptoms will get worse. Ultimately leading, in some cases, to permanent damage to the delicate surface of the eye, including damage to the nerves.
You can find more information about the causes of dry eye and its management at Dry Eye Zone.
And don’t forget to visit Dry Eye Zone and subscribe to the regular free information updates.
If you are experiencing dry eye symptoms then you should ask the advice of your eye care professional. Why not book your next eye examination with an independent optician today.
Sources:
Golden MI, Meyer JJ, Zeppieri M, et al. Dry Eye Syndrome. [Updated 2024 Feb 29]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK470411/#
Efraim Y, Chen FYT, Cheong KN, Gaylord EA, McNamara NA, Knox SM. A synthetic tear protein resolves dry eye through promoting corneal nerve regeneration. Cell Rep. 2022 Aug 30;40(9):111307. doi: 10.1016/j.celrep.2022.111307. PMID: 36044852; PMCID: PMC9549932.
Carlos Belmonte et al. TFOS DEWS II pain and sensation report, The Ocular Surface, Volume 15, Issue 3, 2017, Pages 404-437, ISSN 1542-0124, https://doi.org/10.1016/j.jtos.2017.05.002
Painful Dry Eye Symptoms: A Nerve Problem or a Tear Problem? Galor, Anat Ophthalmology, Volume 126, Issue 5, 648 – 651
Alexia Vereertbrugghen, Jeremías G. Galletti, Corneal nerves and their role in dry eye pathophysiology, Experimental Eye Research, Volume 222, 2022, 109191, ISSN 0014-4835
Shaheen BS, Bakir M, Jain S. Corneal nerves in health and disease. Surv Ophthalmol. 2014 May-Jun;59(3):263-85. doi: 10.1016/j.survophthal.2013.09.002. Epub 2014 Jan 23. PMID: 24461367; PMCID: PMC4004679.
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