Eyeworld

EW REFRACTIVE SURGERY 52 October 2015 by Maxine Lipner EyeWorld Senior Contributing Writer tive but also their conjunctiva and other nerves even in the distribution of some of the branches of the tri- geminal nerve. It's pretty compelling evidence there are a lot of analogous processes being described." Also, there is the phenomenon of "pain without stain," she said. "In a lot of these patients, if you're looking at objective signs of changes in the tear film or irritation of the cornea, you won't find anything on someone stubs a toe after breaking it, post-LASIK patients are hypersen- sitive to light, wind, and eye drops, she said. Likewise, neuropathic pain patients can have secondary hyper- algesia in which not only the area of initial injury is more sensitive to pain but also the tissue in the surrounding area, served by nerves in the same pathway, Ms. Levitt said. "For some of these dry eye patients not only is their cornea more sensi- Parallels to pain "Almost all of those studies showed that this regimen was able to de- crease the frequency of persistent symptoms after surgery," Dr. Galor said. "When we were looking at the epidemiology we found it was interesting that the chronic symp- toms after other surgeries are very similar to those of LASIK." Inves- tigators gleaned that at 6 months postoperatively, 20–30% of LASIK patients have chronic symptoms, as did 10–20% of mastectomy, tho- racotomy, and surgical gallbladder patients. "There have been so many surgeries where this model has been used," Dr. Galor said. "What we wanted to do in our review was to highlight those parallels to say that maybe strategies to treat persistent symptoms in those models would also work in LASIK patients." Investigators did indeed find parallels. Ms. Levitt pointed out that there are a lot of striking similarities between persistent pain in other fields and symptoms described by postoperative LASIK patients. Akin to the sensitization that occurs with what's referred to as allodynia in neuropathic pain, such as when A pain imposter? A ll too commonly, af- ter undergoing LASIK patients come in com- plaining of what appears to be dry eye. Data from the literature suggest that from 20 to 55% of post-LASIK patients have chronic dry eye symptoms such as a burning pain, a feeling of irritation evoked by heat or cold, and sensi- tivity to light or wind, according to Alexandra E. Levitt, a fourth- year medical student, University of Miami. However, in some of these cases dry eye may be an erroneous description. Recent findings in the April 2015 issue of Molecular Pain indicate that there is a lot of overlap with the way patients would also describe neuropathic pain elsewhere in the body, Ms. Levitt reported. Launching such a study was only logical, pointed out fellow investigator Anat Galor, MD, staff physician, VA Medical Center, and associate professor of clinical oph- thalmology, Bascom Palmer Eye In- stitute, Miami. "We know that when we do LASIK we sever nerves," she said. "It makes sense for us to say, 'Let's look at other models in other fields and see what those fields have done to try to combat persistent symptoms after other surgeries.'" Thinking of LASIK in terms of its neurobiology of severing nerves and considering what can be done to remedy symptoms stemming from this is important, she thinks. Ms. Levitt described the study as a systematic review of this theme of LASIK being linked to other types of persistent pain. "We were trying to pull from the LASIK-specific liter- ature the neuroscience of corneal pain and persistent postoperative pain elsewhere in the body," she said, adding that the idea was to try to systematically review those fields. This could offer valuable in- sights for LASIK practitioners, Dr. Galor said. In guarding against post- operative problems when surgery is done elsewhere in the body, such as for mastectomy and hysterectomy, she pointed out that there have been studies examining the use of nerve protectants such as pregabalin or gabapentin for patients just prior to—and a few days after—surgery. Dryness after LASIK " Taking the time to ask about depression and chronic overlapping pain and working with pain specialists and mental health experts is vital to getting to the problem. " –Anat Galor, MD For some post-LASIK patients it may be important to think about corneal nerves and their role in propagating dry eye. Source: Anat Galor, MD

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