Dry Eye Treatment in Encino & West Hills, CA
The treatment of dry eye continues to be a difficult challenge for eye care practitioners. In particular, although we know the anatomy of the tear film and the methods needed to diagnose dry eye, we often cannot provide treatment that relieves symptoms for our patients. Many patients complain bitterly about burning, scratching and irritation, yet their symptoms don’t correlate with significant abnormal finding on their examination.
Often patients become frustrated with their ophthalmologist, and often the ophthalmologist becomes frustrated with the patients. As ophthalmologists, we want to help our patients to the best of our ability, so we become concerned when we are unable to alleviate the symptoms that make our patients miserable and are unable to find the typical signs of dry eye that we look for when we examine patients. In fact, Dr. Aizuss finds himself frequently having to tell his patients that the good news is that the surface of their eye looks fine. However, that is also bad news, since patients don’t come to the office for their entertainment. Patients come to the office because they are not feeling well and their discomfort is impacting their lives.
Dry Eye & Pain
In 2009, Perry Rosenthal MD observed what they diagnosed as corneal neuralgia, which they termed, “pain without stain” because there was not the usual staining or stippling of the cornea that is often seen in dry eye patients. They speculated that the pain symptoms could be a neuropathic pain, as opposed to qualitative or quantitative disturbance of the tear film. Dr. Rosenthal later determined that nerves in the eye are critical to the proper functioning of the eye because they provide feedback on the functioning of the tear film. These nerves could become dysfunctional, causing increased sensitivity of the eye’s natural alarm system, and sending pain signals that are disproportionate to the physical findings. In fact, there may be no physical findings at all!
The dry eye community of doctors and patients has become increasingly interested in the neuropathic dry eye. Neurosensory abnormalities are now specifically listed as a cause of dry eye. However, at this time there are no dry eye therapies that specifically target neuropathic pain related to dry eye. As a result, marijuana and its derivatives, such as tetrahydrocannabinol (THC), the main ingredient in recreational and medical marijuana, are becoming of interest in the treatment of dry eye related neuropathic pain.
Cannabinoid receptors are known to modulate pain and inflammation and are located throughout the eye, including in the corneal surface cells and the retina. They are also on immune cells and may play a role in wound healing. It is difficult to perform research on this in the United States due to the stance of the federal government on the legality of marijuana, even while various states have passed laws that legalize marijuana for both medicinal and recreational use. Research is underway in Germany to further clarify the role of cannabinoid compounds in the treatment of dry eye neuropathic pain.
Marijuana and Dry Eye
Smoking marijuana or eating marijuana edibles is not a practical method of treating ocular disease. These systemic methods of consumption produce unpredictable doses with a variety of often unwanted side effects. As a result, most professional organizations, such as the American Academy of Ophthalmology, have taken positions opposed to the use of systemic THC treatments for ocular conditions. Cannabinoid eye drops are under investigation and development, but have proven difficult to formulate as it is difficult to produce eye drops that can get the THC into the target ocular tissues. Studies in Europe have demonstrated that there is a vehicle that may adequately deliver THC to the ocular surface, and that shows promise in improving both pain scores and the severity of the ocular surface disease. In addition, these same studies show the linkage between patients with clinical depression and ocular surface disease. We look forward to the publication of these studies and the development of THC based therapies in the United States that may benefit our dry eye patients.