Eyeworld

MAR 2012

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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March 2012 Refractive February 2011 EW FEATURE 89 scratchiness, or something as vague as pure pain. The first step toward a diagnosis is differentiating between discomfort from dry eye, blepharitis, and corneal pain. "There's a continuum of disease The subbasal nerve layer 1 year after LASIK in a patient with keratoneuralgia. There are very faint nerves and a large number of hyper-reflective immune cells that's partially due to the dry eyes patients develop after refractive surgery and partially due to inflam- mation, which is leading to the corneal neuralgia," explained Pedram Hamrah, M.D., director, Ocular Surface Imaging Center, Henry Allen Cornea Scholar, Cornea & Refractive Surgery Service, Massachusetts Eye & Ear Infirmary, Boston. "In dry eyes, you can obvi- ously see the surface staining and other dry eye signs. In corneal neu- ralgia alone, you don't see these signs. It's just the symptoms of the patient." A simple slit lamp examination The same patient. Another area in the same plane with no immune cells, but with increased reflectivity of nerves and beading (signs of inflammatory nerve changes) is not enough to diagnosis this con- dition, Dr. Hamrah said. You must examine these patients on a cellular level with an in vivo confocal micro- scope. Using this, "you can see in- flammation lingering," he said. "You can see abnormalities of the nerves. There are things we can detect on a pathological level, but not at the slit lamp level necessarily." Other telling symptoms include exaggerated pain response to touch, air, and drops; lowered Schirmer's scores, but frequently borderline or within the normal range; and depressed cornea sensitivity by Cochet-Bonnet esthesiometry. "There's a high likelihood we've all seen patients like this and attrib- uted it to something else," Dr. Cason said. If patients aren't responding to dry eye treatments such as artificial tears and anti-inflammatories, he said, "our suspicion has to be high." A similar area in a normal subject Source (all): Pedram Hamrah, M.D. plained. "So for example, corneas can heal perfectly fine and normal. But you can't see the nerve circuitry. The ophthalmologist just assumes if you can't see it, it isn't there. This is wrong. If a patient has chronic pain and you can't see it, it's neuropathic pain unless proven otherwise." Diagnosing the pain Patients with corneal neuralgia may complain of burning, stinging, A multidisciplinary treatment plan Depending on the disease stage, pa- tients with corneal neuralgia may need special, usually multifaceted, treatment. If caught and treated early, patients respond fairly well. "When I am referred [patients] 2-3 months after LASIK and they have pain, almost all of them have lingering inflammation," Dr. Hamrah said. When treated, the neuralgia goes away. However, "if the patient has had this for 6 months to a year, that becomes difficult to treat," he said. Dr. Rosenthal agreed that cen- tral sensitization could be avoided if the pain is treated early. "I theorize that if we limit the pain and enhance the healing of the nerves and the corneal epithelium, theoretically this devastating cen- tralized pain may be aborted," Dr. Rosenthal said. "I think there's a chance of developing that type of intervention." For advanced disease, Dr. Cason recommended treating the dry eye conditions with lubrication, anticonvulsants, tricyclic antidepres- sants and serotonin reuptake in- hibitors, and the scleral reservoir lens and evaporation-prevention goggles. The problem with the scle- ral lens is some patients have sensi- tivity in the conjunctiva and may feel the lens under their eyelid. "Despite the fact that the cornea is completely bathed in fluid, they still have pain sensation," he ex- plained. "Unfortunately, a lot of these patients aren't helped by this." Dr. Hamrah has had some suc- cess with autologous serum tears (AST), which promote nerve regener- ation. AST can be problematic to prescribe though, as not all com- pounding pharmacies make it. "If the pain has shifted toward the brain and there's a central sensi- tization, you have to co-manage The femtosecond continued from page 87 surgery is better. But I typically will not offer a choice to the patient. My initial experience with this approach is quite good. Patients embraced the new technology readily," he said. In Australia, Michael Lawless, M.D., clinical senior lecturer, University of Sydney, also offers laser cataract surgery as his standard. "Every staff member from the time we began in April knew that we were introducing this technology be- cause it has the potential to revolu- tionize how we do cataract surgery. We felt that the small amount of data in the published literature sup- ported this, and my experience here in 2011 has assured me that this new technology has promise," he said. He doesn't talk to the patients much about the laser side of the pro- cedure; his clear message is that it's the way he prefers to do it as long as patients are suitable candidates for the procedure. His main discussion revolves around what type of intraocular lens would be best suited to the patient as well as the risks, benefits, and complications involved. EW Editors' note: Drs. Desai, Knorz, Lawless, and Solomon have financial interests with Alcon. Dr. Hu has no financial interests related to this article. Contact information Desai: 727-518-2020, desaivision@hotmail.com Hu: 817-540-6060, jerryganghu@hotmail.com Knorz: knorz@eyes.de Lawless: 61-29-4249999, michael.lawless@vgaustralia.com Solomon: 843-792-8854, kerry.solomon@carolinaeyecare.com these patients with neurologists or pain specialists," Dr. Hamrah said. "They have a variety of things [from] systemic medication to nerve blockers to acupuncture." Preventive screening A key to understanding corneal neu- ralgia and preventing it from occur- ring in the first place is identifying the patients at risk. "I strongly believe that one of the significant risk factors is autoim- mune disease," Dr. Rosenthal said. Diseases to screen for include Sjogren's syndrome, fibromyalgia, chronic interstitial cystitis, irritable bowel syndrome, chronic fatigue syndrome, and multiple chemical hypersensitivities. "One of the important parts in getting patient history is detailing any possible symptoms of autoim- mune disease such as dry mouth. Go down the whole list," Dr. Rosenthal said. "Is there family history of neuropathic pain elsewhere in the body?" In that case, one has to ask, should systemic pain disorders be a contraindication to refractive sur- gery? "Yes," Dr. Rosenthal said. "Laser keratorefractive surgery is not treat- ing a disease. If you're dealing with a healthy tissue, then the complica- tion rate should be zero. I'm sure continued on page 91

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