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EW GLAUCOMA 58 May 2015 "That substance hitting the surface of the eye again and again for days, weeks, months, and years on end can cause irritation to the surface of the eye," he explained. Also, the medication itself can potentially cause dry eye and irritation, he said. by Maxine Lipner EyeWorld Senior Contributing Writer Scanning the glaucoma fiel Considering how medications impact the surface I t is an all too common issue for glaucoma patients—ocular sur- face problems. While approx- imately 15–20% of elderly pa- tients have some type of ocular surface disease, for those with glau- coma the incidence rises to about 40–50%, according to Jeffrey A. Kammer, MD, associate professor of ophthalmology, Vanderbilt Universi- ty, Nashville, Tenn. "Unfortunately, we're so geared toward watching the pressure, checking the visual field, and looking at their OCT or for any optic nerve head changes that we sometimes overlook these problems that patients almost always discuss," Dr. Kammer said. Patients often refer to symptoms such as foreign body sensation, redness, blurred or fluctuating vision, and scratchiness, he said. Irritation issues Glaucoma patients even without medication have been found to have a higher rate of ocular surface dis- ease and dry eye, Dr. Kammer noted, adding that the pressure-lowering drops can exacerbate the problem. "Glaucoma medications can have both short-term and long-term effects on the ocular surface," he said. In the short term, he finds, medications can disrupt the tear film. From a long-term perspective, they can affect the goblet cells, cause fibrosis, and disrupt the epithelium, he said. Parag Parekh, MD, Laurel Eye Clinic, Brookville, Pa., also finds that surface issues are a problem for many patients. "I put patients on a drop and typically I have them back 1 month later to see how they're making out," he said. In addition to consid- ering whether the drop lowered the patient's pressure, he looks into just how well the medication is being tolerated. "Some people have a reac- tion right away and some are OK the first few weeks, and then another month or 2 goes by and they have a reaction to it," he said. There are multiple factors in- volved here, Dr. Parekh said. The ve- hicle that the medication is in often has BAK (benzalkonium chloride). Significant co neal irritation (epithelial irregularity) can be visualized using direct illumination through the slit lamp. BAK-induced epithelial keratitis is highlighted using fluo escein staining. Source: Jeffrey A. Kammer, MD Dr. Kammer agreed that not just the preservatives but also the med- ications themselves can be a factor. "Prostaglandins, because they can be pro-inflammato y, can certainly be more harsh on an eye that has a compromised ocular surface to begin with," he said. "But to be fair, any of the medications have the poten- tial of aggravating clinical dry eye syndrome." With any glaucoma patient who has underlying dry eye or ocular surface disease, Dr. Kammer Pharmaceutical focus