Eyeworld

EW CORNEA 90 April 2016 by Liz Hillman EyeWorld Staff Writer Veterans Affairs Medical Center, and associate professor of clinical ophthalmology, Bascom Palmer Eye Institute, University of Miami Health System. "We need to realize that some of these are not going to be fully explained by what we see on the ocular surface, and we're going to need help from other specialties." Dr. Galor led research that was recently published in the Journal of Pain 1 that evaluated about 150 patients with dry eye symptoms and quantified other chronic pain syn- dromes (CPS), separating them into a group with lower CPS and a group with higher CPS. Galor et al. hypothesized that patients with higher CPS would have a different dry eye phenotype than those with lower CPS—and they were right. "The diagnosis of [dry eye] is applied to a heterogeneous collec- tion of clinical syndromes char- acterized by ocular irritation and visual disturbance, often described in terms of a 'foreign body sensa- tion' or 'dryness,'" the study authors New research suggests ophthalmologists may need to look beyond the ocular surface in dry eye cases A patient sits across from his ophthalmologist complaining of itchy and gritty eyes, pain, and redness. In most cases, the physician would look at the ocular surface, evaluate the patient's health history, and analyze his tear production. Depending on a variety of factors, a likely diagnosis could be dry eye. But a group of researchers out of the University of Miami now challenge ophthalmologists to think beyond the ocular surface when it comes to dry eye, at least for a possi- ble subset of patients. "When people come in, they're coming in with symptoms, and it's our job to figure out why they're having those symptoms," said Anat Galor, MD, staff physician, Miami wrote. "However, some commonly reported features of a [dry eye] type of discomfort parallel the symp- toms characteristic of neuropathic pain commonly seen in CPS. … Our results provide evidence for the existence of a subset of [dry eye] patients whose ocular symptoms might be the manifestation of an underlying central pain processing disorder." Of the 149 subjects included in the study, 97 were characterized as having high CPS. No significant difference was seen on the ocular surface between patients with high or low, but those in the high CPS group had more or greater dry eye and ocular pain symptoms, as well as lower scores on psychiatric and quality of life assessments. Galor et al. stated that their findings supported other studies that suggest neuropathic ocular pain could represent a central sensitivity syndrome and that a possible sys- temic predisposition to pain could connect several pain conditions. While the mechanism for this has not yet been determined, Galor et al. noted the possibility for "aberra- tions in proinflammatory cytokine signaling and glial cell-neuron inter- actions" as well as genetic factors as possible causes. As Roy Levitt, MD, vice chair of translational research and academic affairs, Department of Anesthesi- ology, Perioperative Medicine, and Pain Management, University of Miami, said "it does appear that in some cases there is a central somato- sensory component to this and that central somatosensory dysfunction is underlying these symptoms that are comorbid." Dr. Galor said they hypothesize the susceptibility genes or other gene types could play a role in these conditions. "It may tie in to having pain in your shoulder and pain in your back and pain in your eye," she said. "Like everything else in life, it's a combination of both genetic and environmental factors." Stephen Pflugfelder, MD, di- rector of the Ocular Surface Center, Baylor College of Medicine, Hous- ton, who was not involved with the study, supported the researchers' findings. "I agree with their findings and conclusions that there is a subset of dry eye patients who have more se- vere complaints that are out of pro- portion to their objective findings, and in some cases patients have moderate dry eye symptoms with no signs of dry eye," Dr. Pflugfelder said. "It is not unusual that these patients may experience other types of chronic pain or have fibromyal- gia. A multidisciplinary approach may help these patients deal with the pain or at least develop coping mechanisms." The American Academy of Ophthalmology developed Pre- ferred Practice Pattern guidelines for dry eye syndrome in 2013 and mentioned that systemic diseases and systemic inflammatory diseas- es, such as Sjögren syndrome and rheumatoid arthritis, can affect the nerves that stimulate tear produc- tion, resulting in dry eye condi- tions. 2 Galor et al. also cited research by Vehof et al. 3 that suggests "shared Study indicates central pain disorder may be at the heart of some dry eye symptomatology Dr. Galor performs a corneal sensitivity test with a modified Belmonte aesthesiometer to test somatosensory function in patients with dry eye. Source: Miami Veterans Affairs Medical Center continued on page 92

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