Eyeworld

EW CORNEA 32 September 2011 Practitioners stress the importance of keeping an eye out for keratitis despite controls U nfortunately it's part of the risk of corneal trans- plantation—bacterial in- fection. Spotting and getting a handle on this can be imperative to having a good outcome. Eduardo C. Alfonso, M.D., pro- fessor and chairman, Bascom Palmer Eye Institute, Miller School of Medi- cine, University of Miami, finds that the most common type of bacterial keratitis that practitioners must deal with is the late type, which involves external influences such as a suture that has become infected or contact lens use that has brought bacteria to the eye. Also commonly affected are cases in which transplant patients have an underlying disease such as dry eye or glaucoma, which require multiple medications that can cause some damage to the surface epithe- lium. In addition, those who under- went corneal transplant in the first place due to infection are at an in- creased risk. However, the scenario in the back of most practitioners' minds is the one where the donor may have played a role. "The donor may have had a particular bacteria that was carried on the cornea and now the patient develops a corneal infection or possibly an endophthalmitis asso- ciated with this," Dr. Alfonso said. While possible, this is rare, he finds. Keeping rates low This is unusual because eye banks keep tight control of infections re- lated to transplants with donor rim cultures. One of the reasons these are done is for patient care. "We want to know what the organism growing on the rim is so that we can monitor the patient carefully for a potential initiation of an infection, and we can know if it's likely to be the same organism," Dr. Alfonso said. In addition, at Bascom Palmer, with its own eye bank, donor rims are monitored in order to ensure quality. "We want to make sure that if there is any problem, we pick it up early," Dr. Alfonso said. "If we saw a number of corneal rims that were positive we would immediately look at our policies and procedures in eye banking to make sure that there has- n't been any break in the standard operating procedure." The chances of a positive donor rim being associated with an actual bacterial keratitis infection, how- ever, are very low. "It's probably less than 10%, and in some studies it has been as low as less than 1%," Dr. Alfonso said. However, if the rim is positive, practitioners are advised to keep closer tabs on patients. "We would call the patient back and see him or her every 48 or 72 hours. We would carefully educate the patient that if he or she notices any decrease in vision, redness, or anything that could be a sign of an infection to come in immediately," he said. One of the most important things that he tells all corneal trans- plant patients is to remember the abbreviation RSVP. "R is for redness, S is for sensitivity to light, V is for decreased vision, and P is for pain," Dr. Alfonso said. "We tell patients that if any of these things are hap- pening and are different from before they need to come in right away be- cause this may be a sign of an infec- tion or a rejection." Francis S. Mah, M.D., co-med- ical director, Charles T. Campbell Ophthalmic Microbiology Labora- tory, University of Pittsburgh School of Medicine, finds that the peek time for infection tends to be in the first couple of weeks after penetrat- ing keratoplasty. "We've cut all the corneal nerves that go into the cen- tral cornea, and the epithelium that's on the donor still has to be re- placed by the host's epithelium," he said. "There's going to be this transi- tion of epithelial defect." He pointed out that there's also increased risk in transplant patients because of the use of steroids. "The main drug of choice to help prevent rejection is steroids, and these are used for long periods of time," Dr. Mah said. Like Dr. Alfonso, Dr. Mah stressed that risk of transmission of bacterial keratitis is low due to screening and serology at the eye bank. "It's pretty rare that patients get an acute infection from trans- mission of the infectious agent from the actual donor as far as bacteria," he said. "Part of it is when they're stored by serology they're also stored in Optisol (Bausch and Lomb, Rochester, N.Y.), which is the main anti-infective." This targets a lot of bacteria and some fungus as well. Dealing with possible infection In cases where infection does occur in a patient who has undergone penetrating keratoplasty, the first priority is to identify the source. "In light of steroid use the appearance may not be typical so you may not get exactly what you are used to," Dr. Mah said. "It would be recom- mended to culture these patients." He advised practitioners to first manage the infection and then deal with the possibility of rejection af- terward. "In my mind you've got to treat the infection first and at least control that before you start worry- ing about rejection," he said. In DSEK cases if the infection occurs acutely after surgery and hap- pens to be in the space between the transplant and the cornea, Dr. Mah stressed it's going to be important to get access to that area. "If you can't get access to that area, you might have to remove the graft and treat the infection," he said. "As far as more common scenarios such as surface keratitis, it's pretty much treated like any other bacterial acute type of keratitis." In general for more severe infec- tions Dr. Mah suggested using a combination of medication. "I per- sonally will use the fluoroquinolone and then another fortified agent like cefazolin. If it looks like it's a Gram- negative then I'll add tobramycin after that," he said. "There are some areas where fluoroquinolones are be- coming more resistant so practition- ers might choose to use different agents in different regional areas." Going forward, Dr. Mah thinks that with the increase in DSEK pro- cedures the overall risk of infection is going to decline. Among other things, the cornea is less neu- rotrophic. "In general I think that we're using fewer steroids with DSEK surgery because we're transplanting less tissue," Dr. Mah said. The result, he thinks, will be a more physiologic cornea post-op with fewer infec- tions. EW Editors' note: Dr. Mah has financial in- terests with Alcon (Fort Worth, Texas), Foresight Biotherapeutics (New York), and Merck (Whitehouse Station, N.J.). Dr. Alfonso has no financial interests related to his comments. Contact information Alfonso: 305-326-6366, ealfonso@med.miami.edu Mah: 412-647-2214, mahfs@upmc.edu by Maxine Lipner Senior EyeWorld Contributing Editor The graft that went south: Diagnosing and managing infectious keratitis An example of acute bacterial keratitis Source: Francis S. Mah, M.D.

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