Eyeworld

58 | EYEWORLD | WINTER 2025 C ORNEA by Ellen Stodola Editorial Co-Director About the physicians Gerami Seitzman, MD Professor and Medical Director Francis I. Proctor Foundation for Research in Ophthalmology University of California, San Francisco San Francisco, California Sonal Tuli, MD, MEd, MBA Professor and Chair Department of Ophthalmology University of Florida Gainesville, Florida pneumoniae, Pseudomonas aeruginosa, and Moraxella. "However, a common pathogen with an uncommon resistance pattern, for example a pan-resistant pseudomonas, could be con- sidered atypical in some settings because it is unexpected," she said. Viral keratitis from HSV or VZV is also common. By contrast, she said that CMV, EBV, mea- sles, and mpox are atypical viruses for keratitis. "As a general rule, organisms most cornea spe- cialists would consider atypical include Acan- thamoeba, atypical mycobacteria, Achromobacter spp., Citrobacter spp., and Pythium insidiosum." A common clue for atypical keratitis is pro- gression despite appropriate therapy for a typi- cal infection, Dr. Seitzman said. Acanthamoeba often begins as a patchy, rough epitheliopathy, while Nocardia may present with more fine, wreath-like infiltrates. Atypical mycobacteria may present late after surgery, with indolent infiltrates at incision sites or under LASIK flaps. Pythium can mimic fungal keratitis, often with linear, tentacle-like infiltrates. Viral atypical keratitis, such as CMV endotheliitis, may show coin-shaped keratic precipitates. Recognizing these clinical patterns can sometimes raise sus- picion early, Dr. Seitzman said. Dr. Tuli agreed that the typical infectious keratitis that occurs in the U.S. is bacterial. However, she noted the fungal infections are more common in Florida and other southern states. These are atypical because they don't respond to regular antibacterial (need antifun- gals), can continue to grow deeper in the cor- nea, and penetrate the Descemet's membrane, even with treatment, Dr. Tuli said. Steroids are O phthalmologists, particularly corneal specialists, may encounter a variety of pathogens that can cause infec- tious keratitis. Gerami Seitzman, MD, and Sonal Tuli, MD, MEd, MBA, went into detail on some of these infections, in- cluding those that may be considered "atypical," and how to identify and diagnose them. Dr. Seitzman started the discussion by acknowledging "what is odd for you may be normal for me," particularly noting that what is "atypical" varies in different practices and patient populations around the country and around the world. An "atypical" corneal infection refers to one caused by organisms that are not commonly en- countered in day-to-day practice, she said. "But what counts as atypical depends on where you are seeing patients. For example, fungal kerati- tis is the leading cause of infectious keratitis in South India, but in my practice in San Francis- co, it's less common cause. Similarly, Nocardia (a type of bacteria) would be considered atypi- cal in North America or Europe, but in parts of India and South Asia, it is a more well-recog- nized etiology of infectious keratitis." For this reason, she said it's important for ophthalmologists to define what is typical for their practice settings, their latitude, and their patient populations. "The best way to know this is to culture routinely and keep track of local surveillance data," she said. Dr. Seitzman said that organisms most cor- nea specialists would consider "typical" are bac- terial pathogens, including Staphylococcus au- reus, Staphylococcus epidermidis, Streptococcus Looking out for atypical cornea infections Photo of Acanthamoeba showing patchy infiltrates and pathognomonic perineuritis Source: Sonal Tuli, MD, MEd, MBA Photo of fungal ulcer showing typical dry infiltrate with feathery borders Source: Sonal Tuli, MD, MEd, MBA

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