Dry Eye and Chronic Pain
The American Eye Institute estimates that dry eye affects about 3 million Americans every year, and it affects more women than men. My ophthalmologist (a medical physician that specializes in treating eye diseases) tells me they are seeing an upsurge in dry eye as a disease. You might be surprised as to why that is the case.
Dry eye is a complex condition that occurs when we don’t produce enough tears or lubrication evaporates because of inflammation of the glands around the eye and lids. It can occur with other health disorders, with aging, or as a primary problem. The causes and symptoms vary. Other contributing factors include injury or infection, our environment, chronic pain disorders associated with nerve problems in the brain, and sensitivity syndromes. Any problem or injury that interferes with normal function of eyelid movement or lubrication of the eye can cause dry eye syndrome (DES) or dry eye disease (DED).
Rising numbers of people with DES may be the result of technological advances. Prolonged exposure to computer screens, and personal devices, known as “Computer Vision Syndrome” is the culprit here. As an emergency nurse, I gave aftercare instructions to patients after eye injury (one of those other potential causes of dry eye). The instructions were to stare, such as watching television or reading. This is because staring diminishes eyelid movement. However, under normal circumstance our blink reflex serves an important purpose. When we blink (something that doesn’t require conscious thought), it provides gentle suction on our tear duct, then our lids evenly distribute mucin, a protein in our tears that coats and lubricates our eyes, protecting them and keeping them healthy, and preventing evaporative stress (caused by staring).
Dry eye as a chronic pain disorder
Not all patients with dry eye experience the same symptoms. In fact, some may experience pain in the absence of usual symptoms, making it more difficult to diagnose. But this doesn’t mean the pain of chronic dry eye (symptoms lasting more than 3-6 months) or the cause is any less real.
When the eye remains continually inflamed and painful from damage or disease, changes can occur in the central nervous system. This is called centralization.
Centralization causes the eyes to become sensitive to things that wouldn’t normally be a problem. It’s like a merry-go-round, with no place to get off. Constant stimulus to the brain causes changes in the brain, and results in the brain responding abnormally. The slightest thing leads to a cascade of events that create a chronic dry eye and pain. In other words, even though pain is in the eyes or surrounding area, it may be generated by a misfiring of nerves and messages in the central nervous system.
Newer research suggests that dry eye syndrome (DES) or dry eye disease (DED) share characteristics of other chronic pain disorders. One study (2012), suggests that DED occurs frequently with migraine (now thought to be a disease originating from nerve problems in the brain, centralized) and migraine may be aggravated or triggered by DED. Vehof J, et al. (2016), studied 425 patients with chronic pain syndromes of irritable bowel syndrome, chronic pelvic pain, and fibromyalgia. Using tests available for diagnosing dry eye, they found through specifically designed questionnaires that DED in chronic pain syndromes are not only common, they are associated with increased severity of DED symptoms.
Stevenson, W,. et al. suggest “immunoinflammatory responses lead to further ocular surface damage and the development of a self-perpetuating inflammatory cycle”. And, in their 2012 study, they found immune inflammatory mediators in in a subtype of DED. It is important to note that immune mediated responses are delegated by the brain, further suggesting a role in the centralization of in characteristics of DED.
Because of the complexity of dry eye, diagnosis can be difficult. Therefore, treatments vary according to the underlying problem and the goal is to ensure lubrication and healthy gland function. Blink training, eyelid scrubs, eye lubricant drops, drops to increase tear production if that is the problem, and a new treatment called Lipiflow to restore gland function in evaporative type dry eye are all things that your opthamologist might discuss with you.
According to Bron, AJ., et al. (2014), there is hope. "With the advent of new tests and technology, improved endpoints for clinical trials may be established, which in turn may allow new therapeutic agents to emerge in the foreseeable future. Accurate recognition of disease is now possible and successful management of DED appears to be within our grasp, for a majority of our patients.”
If you learned something from this article or have something helpful that you can share with us, please leave a comment below. In healing, Celeste