MAR 2014

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

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82 LASIK and PRK procedures pose risk for dry eye disease in some patients D ry eye disease is a "vicious circle," with key mecha- nisms of the disease including inflammation and tear film instability, which can be especially problematic following refractive surgery, said C hristophe Baudouin, MD, Centre Hospitalier National d'Ophtalmolo- gie des Quinze-Vingts, Paris. Speaking at the 2013 European S ociety of Cataract & Refractive Surgeons (ESCRS)/EuCornea Sympo- sium "Refractive surgery in risky corneas: is it really safe for the patient?" Dr. Baudouin showed an image of the theory of dry eye as a vicious circle, with cell damage, nerve stimulation, and inflamma- tion listed as only some of the factors that are driving forces behind the disease. "Whatever the cause or associa- tion of dry eye disease with other conditions, it's important to try to prevent this vicious circle because whatever you do, even if the LASIK was perfect or you removed any kind of medication that could cause the dry eye, the patient will be in a disease that will be self-stimulated," he said. "It's very easy to enter this cycle. It's very difficult to get out." Impact Dry eye has become a major compli- cation of refractive surgery, not only for its severity, but also its frequency, occurring in about 30% to 35% of refractive procedures, he said. In PRK cases, symptoms were reported in numbers ranging from 15% to 45%, while in LASIK cases, that amount ranges from 8% to 48%. "The frequency may be rather high depending on the criteria that we use to define dry eye after sur- gery. We know that it might be transient in the eye, and we also know that it may last up to several years after refractive surgery, and it may be a burden for the patients," he said. Dry eye can cause not only se- vere discomfort, but also issues with vision including fluctuation, he said. It is vital to educate patients before surgery about the risk and potential impact to visual quality. "We have to remind them that dry eye is also a question of poor visual function, if not visual acuity," he said. "It's important to inform pa- tients carefully before surgery that they may not only experience tran- sient dry eye for a few weeks, they may also suffer a manner of months or a year," Dr. Baudouin said. "They may complain a lot about quality of life and quality of vision." Three factors Dr. Baudouin said there are three factors involved in dry eye: the ocu- lar surface, the procedure, and the corneal nerves. For the ocular sur- face, pre-existing dry eye is impor- tant. The duration of dry eye usually lasts for about six months; symp- toms beyond that time are when the complications begin, he said. Assessing patients for dry eye prior to surgery can be key to reduc- ing the complication, he said. "Pre-existing dry eye is obvi- ously a main risk factor, and we h ave to be aware that the part of the dry eye induced by surgery is exacer- bated by the contact lens wearer who is experiencing dry eye and stopped wearing contact lenses re- quiring refractive surgery," he said. He pointed out that it could be difficult at times to determine if dry eye is present because of a variety o f issues, including that signs and symptoms are not specific. Preserva- tives from medication can lead to toxicity issues, he said. "It's not logical to propose BAK-containing eye drops to patients who are suffering from dry eye, especially if the cornea has already been modified by the laser p rocedure," he said. The laser procedure itself can alter the tear film stability and re- duce goblet cell density. The pathophysiology can be specific, he said: "neurotrophic epitheliopathy following transection and/or impairment of sensitive nerves of the anterior corneal stroma." It can also be nonspecific: "exacerbation of pre-existing tear film impairment, often following long-term contact lens wear." Corneal nerve transection can lead to decreased corneal sensation, which causes decreased feedback to the lacrimal gland and reduction of protein, electrolytes, and water secretion. Decreased blinking rate and/or incomplete blinking can also occur, while there is a decreased synthesis of neurotrophic factors, he said. Neurogenic inflammation occurs through overstimulation of abnormal nerves. "There is clearly this connection between the function and the struc- ture of corneal nerves. Sometimes the nerves are totally abnormal, even … after six months," he said. "There's a role to describe in the future to better understand the rela- tionship between inflammation and the nerves." Using tear substitutes postopera- tively can help, Dr. Baudouin said, as well as prescreening patients for existing dry eye. EW Editors' note: Dr. Baudouin has no financial interests related to this article. Contact information Baudouin: baudouin@quinze-vingts.fr EW REFRACTIVE SURGERY 8 2 March 2014 by Erin L. Boyle EyeWorld Senior Staff Writer Dry eye disease poses problems after refractive surgery that practitioners should not be using topical medications in the presence of an epithelial defect that had sustained delivery vehicles in them. It's not simply the Besivance vehicle, he observed, it's anything that is designed to reduce the dose frequency. While Dr. Talamo finds that Besivance can be used for corneal ul- cers with excellent results in general, if you have a large corneal defect, he stressed the need for caution here. "I think the take-home mes- sage is don't put these preparations under a bandage contact lens in the presence of an epithelial defect," Dr. Talamo said. Putting the Besivance under a bandage contact lens follow- ing PRK may deliver a superthresh- old dose, he warned. EW Editors' note: Dr. Talamo has financial interests with Valeant Pharmaceuticals (Quebec), Bausch + Lomb, Allergan (Irvine, Calif.), Alcon (Fort Worth, Texas), Abbott Medical Optics (Santa Ana, Calif.), WaveTec Vision (Aliso Viejo, Calif.), Ocular Therapeutix (Bedford, Mass.), and CXL Ophthalmics (Encinitas, Calif.). Contact information Talamo: JTalamo@lasikofboston.com Epithelial continued from page 81 Dr. Baudouin presented this slide at the 2013 ESCRS meeting. It outlines the "vicious circle" theory of dry eye disease, with the four key mechanisms as tear film instability, tear hyperosmolarity, apoptosis, and inflammation. Source: Christophe Baudouin, MD, PhD 76-87 Refractive_EW March 2014-DL_Layout 1 3/6/14 3:17 PM Page 82

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