Eyeworld

WINTER 2025 | EYEWORLD | 59 C absolutely contraindicated in these cases, she said, unlike bacterial where the Steroids for Corneal Ulcers Trial (SCUT) indicated that more severe bacterial infections may benefit from early steroid therapy in addition to appropriate antibiotics. Another atypical type of infectious kerati- tis that Dr. Tuli mentioned was Acanthamoeba, which she said usually occurs in contact lens wearers exposed to water sources, though it might also be seen rarely after trauma with dirt or soil. This can be slow growing and is often misdiagnosed as herpes initially. There are also no commercial medications available in the U.S. to treat this, and Dr. Tuli said treatment is often required for months. Dr. Tuli called microsporidia an "opportu- nistic infection," which was previously thought to only affect immunocompromised people. She added that it's fairly rare in the U.S., and there is no good treatment. You can get it from swimming in untreated water, and while the epithelial disease resolves on its own or can be treated with antibiotics, like moxifloxacin or antiparasitic medications, the deeper stromal disease usually occurs in immunocompetent people, has no medical treatment, and needs a transplant to treat. For symptoms of one of these infections, Dr. Tuli cautioned to look out for too little pain with HSV or too much pain with Acanthamoeba. For fungus, she noted examination signs such as feathery borders, endoplaques, satellite lesions, pigmentation, or immune rings can be clues to the diagnosis. With Acanthamoeba, Dr. Tuli said to look for perineuritis or ring ulcer. With microsporidia, look for coarse, granular, popcorn-like opacities. There are several tools that ophthalmolo- gists can employ to help diagnose these issues for patients. A confocal microscope helps with fungal and Acanthamoeba, Dr. Tuli said. PCR testing of corneal swabs, using a commercial service such as HealthTrackRx, is another good tool for many of these infections. Culture is also an option for some of them, but she added that special stains are required in the lab for all the atypical ones, so you need to let the lab know what you are looking for. Rarely, corneal biopsy may be needed for deeper infections. Dr. Seitzman stressed that a heightened sus- picion is the first diagnostic tool. "Cultures and smears remain the standard of care, but atypical organisms are often fastidious and may require special media," she said. Corneal biopsy, suture pass techniques, or lifting a LASIK flap may be necessary in some cases. Dr. Seitzman also noted PCR as a help- ful molecular diagnostic tool, but she said it requires the physician to "guess" the target or- ganism. "Primers are only used against the virus we ordered," she said. "Here, false negatives are common if the wrong test is ordered. For ex- ample, if our patient had VZV keratitis, and we only ordered HSV PCR, we would miss learning the etiology. This is one reason why unbiased or 'hypothesis-free' tools like metagenomic deep sequencing are so exciting." Dr. Seitzman further noted that working with her colleague, uveitis specialist and geneticist Thuy Doan, MD, continued on page 60 Acanthamoeba: ring infiltrate Source: Francis I. Proctor Foundation Mycobacteria chelonae: irregular stromal infiltrate in a DSEK wound Source: Francis I. Proctor Foundation

• Cover