Eyeworld

64 | EYEWORLD | SEPTEMBER 2022 C ORNEA Contact Mah: Mah.Francis@scrippshealth.org Meghpara: bmeghpara@willseye.org Relevant disclosures Mah: Santen Meghpara: Santen Dr. Meghpara said that fungal keratitis can be very serious and may not be easy to treat. "Often, the infection is in the deeper layers of the cornea, making it less accessible to topical antifungals," he said. There also may be significant visual risks. "Even if we can successfully treat the fungus, these patients are often left with corneal scars than can affect vision, and they may need a corneal transplant," Dr. Meghpara said. "The worst-case scenario is we cannot get the fungus under control, and this could lead to corneal perforation or even invasion of fungus into the eye, leading to endophthalmitis. This can be devastating." Dr. Mah noted that presentation for fungal keratitis is usually the same as with bacterial keratitis. Patients will typically report acute onset of pain, light sensitivity, discharge, change in vision, redness, and if they're a contact lens wearer, they may associate it with contact lens issues. When they do eventually see a physician, most will start with a topical antibiotic, he said, adding that there are more commercially avail- able topical antibiotics than antifungals. Patients with fungal keratitis may look a little better after this treatment, but ultimately, the problem will persist and further testing will be necessary to diagnose the problem of fungal keratitis, Dr. Mah said. In general, he said two main types of fungi causing infections are classi- fied as filamentous and non-filamentous. Dr. Meghpara said that the three big risk factors for fungal keratitis are trauma from vegetation (like a tree branch), contact lens use, and topical corticosteroid use. When looking for warning signs, he suggested that it's important to keep these three factors in mind for all pa- tients who come in with a corneal infection. "It takes a high level of suspicion to make the diagnosis early," he said. "We also look at the characteristics of the infiltrate. Classical- ly, fungal keratitis presents with a gray/white infiltrate with 'feathery' edges. Sometimes there are satellite lesions." However, he noted that the appearance can vary. Treatment options Dr. Mah said, there's only one FDA-approved, commercially available topical antifungal for fungal keratitis, natamycin. He said this treat- ment works well but added that it tends to work better against filamentous forms of fungal keratitis. The other agents that can be used for treatments are typically compounded, Dr. Mah said, and these include amphotericin B and voriconazole. He noted that amphotericin B might work slightly better with non-filamentous types of fungal keratitis, while voriconazole works well for both types. Dr. Mah noted several challenges with treat- ment options. The first is that these antifungals are large molecules and generally don't get through the corneal epithelium very well. So as the epithelium heals, it's hard for the drugs to get through. Another challenge is that fungi usually mu- tate quickly and become resistant quickly. For this reason, Dr. Mah said it's better to treat with two agents so that resistance doesn't become an issue. When beginning to treat these patients, Dr. Meghpara said you need to start by perform- ing a corneal culture. "We culture most of our suspected corneal infections anyway, but we always culture patients in whom we are suspi- cious of fungus," he said. "If we get a positive culture with sensitivity results, we can tailor our treatment to what the fungus is most susceptible to," he said. "If the drops are not working as well as we would like, sometimes we use oral medication." Dr. Meghpara utilizes oral voriconazole but said it's important to be careful with this, as it can cause liver toxicity. He noted the impor- tance of monitoring the patient's liver enzymes. "Sometimes the infection remains uncontrolled, and we have to do a therapeutic corneal trans- plant to essentially cut out the infection," he added. Dr. Meghpara said the earlier the treat- ment is started, the more successful the result. However, even with resolution of the infection, patients can still be left with significant corneal scars. Treatment for fungal keratitis can take a very long time, Dr. Meghpara said, so it's important to counsel patients about this. It may take several weeks at minimum and up to months to treat. continued from page 63

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