Eyeworld

EW CORNEA 84 October 2018 by Lauren Lipuma EyeWorld Contributing Writer fungal, and a hematoxylin and eo- sin stain to look for Acanthamoeba. "If you don't have access to culture medium, it's because you haven't tried to get access to culture medium," said John Berdahl, MD, Vance Thompson Vision, Sioux Falls, South Dakota. "Get a fridge, talk to your local hospital. It's on you if you don't have access to it." Also look for clues in the patient's history, like contact lens wear, exposure to vegetative matter, or swimming in lakes or rivers, Dr. Ayres said. Minimize steroid use un- til the infectious agent is identified and do a careful history and exam, looking for neurotropism and lid abnormality, he added. Experts recommend identifying the infectious agent and modifying treatment C orneal ulcers are com- mon but can be difficult for ophthalmologists to diagnose. It is not al- ways easy to identify the underlying infection, and when the ulcer is unresponsive to the first line of treatment—a fluoroquinolone— physicians may be unsure what to do next. Cornea specialists addressed this issue during the "Cornea Essentials" symposium at the 2018 ASCRS•ASOA Annual Meeting. The purpose of the session was to run through common cornea scenarios and discuss some of the questions that come up when treating these patients, said Francis Mah, MD, Scripps Clinic Medical Group, La Jolla, California, who moderated the session. Brandon Ayres, MD, cornea service, Wills Eye Hospital, Phila- delphia, described a two-pronged approach for treating corneal ulcers that are unresponsive to fluoro- quinolones. First, identify the infectious agent, if possible; second, modify your treatment based on what you find. Ophthalmologists can't always identify which kind of microbe is causing the infection, but culturing a sample of the cornea may offer some clues, according to Dr. Ayres. "There is no way you can look at a corneal ulcer and say, 'I know what this is,' because you will get tricked," Dr. Ayres said. "But you can get a general sense of the infec- tious agent. It does help you steer what you're going to do." Identifying the infectious agent At the slit lamp, use topical anesthe- sia and a sterile spatula or calcium alginate swab to get a tissue sample from the cornea, Dr. Ayres said. Cul- ture the sample in several types of culture medium, like blood, choco- late, Sabouraud, and thioglycollate. Use the cultures to perform multiple smears; do a Gram stain to see if the bacteria is Gram positive or nega- tive, a calcofluor stain to see if it is How to treat corneal ulcers unresponsive to fluoroquinolones An ulcer caused by Streptococcus pneumoniae infection. Most corneal ulcers are bacterial and Gram positive. An ulceration caused by pseudomonas bacteria that has spread to the sclera Fungal keratitis present under a LASIK flap Keratitis caused by Acanthamoeba infection Source (all): Brandon Ayres, MD continued on page 86 Presentation spotlight

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