Excerpt from "Treating Unexplainable Pain, by Faith A. Hayden, EyeWorldLink to Source
What can be done for patients with post-LASIK corneal neuralgia?
A 30-something female with a history of bilateral, uncomplicated LASIK 2 years prior comes into your office complaining of persistent burning pain, almost a foreign-body sensation in both eyes. A simple breeze across her face is excruciating. The pain is so severe it prevents her from living a normal life, and she has thoughts of suicide. The slit lamp examination, though, is overwhelmingly unremarkable and free of corneal staining. Maybe she has slightly variable tear function or reduced tear break-up time, but there's nothing to warrant her extreme symptoms. "Patients go to their ophthalmologists, some of them suicidal because of the pain, and their eyes on the slit lamp look perfectly normal," said Perry Rosenthal, M.D., founder, Boston Foundation for Sight. "Doctors send them to a psychiatrist because they think the [patients are] exaggerating. It just adds to the patients' burden."
Before you dismiss this patient as a crazy hypochondriac and send her on her way, consider corneal neuropathic disease, an extremely rare condition that causes intense pain along corneal nerves. "The hallmark of this disease is how uncomfortable patients are. These patients are very difficult to treat and keep coming back to your clinic, failing all the therapies you give them," said LCDR John B. Cason, M.D., cornea, external disease, and refractive surgery, Naval Medical Center, San Diego, during the 6th Annual International Military Refractive Surgery Symposium held in San Antonio in early January. "Because of that, many of us think they're just making it up. These patients have a true disease process, it's just not well understood."
What causes corneal neuralgia?
No one knows exactly what causes this neuropathic pain to develop after photorefractive keratectomy (PRK) and LASIK, but there are some theories. First, it's important to note that the cornea is the most powerful pain generator in the human body, 200 times more powerful than skin. "The most common cause of neuropathic pain anywhere in the body is damage to the sensory nerves," Dr. Rosenthal said. "Obviously, LASIK and PRK are classic examples of this. It's what happens next after the damage that determines if the post-op pain resolves as the corneal tissue heals or whether it triggers the development of that chronic disease called neuropathic pain."
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