Misdiagnosed as Fungal Keratitis: Herpes Simplex Virus-1 Keratitis Confirmed by Next-Generation Sequencing

The purpose of this study was to report a case of herpes simplex virus-1 (HSV-1) keratitis misdiagnosed as fungal keratitis due to its clinical presentation being similar to that of fungal keratitis, ultimately diagnosed by NGS. A 59-year-old male presented with reduced vision in the right eye, combined with a history of trauma with vegetative matter. The corneal ulcer was accompanied with feathery infiltration, satellite lesion, and endothelial plaques. In vivo confocal microscopy (IVCM) showed hyper-reflective linear, thin, and branching interlocking structures. Fungal keratitis was diagnosed. Voriconazole 100 mg orally daily, topical tobramycin and 1% voriconazole were initiated empirically right away. The condition was aggravated and penetrating keratoplasty was performed. Anterior segment optical coherence tomography (AS-OCT) demonstrated the presence of plaques with a clear boundary between plaques and endothelium, resembling the AS-OCT images observed in cases of viral keratitis. Next-generation sequencing (NGS) further detected HSV-1 deoxyribonucleic acid, and no fungal component was found. Antifungal agents were discontinued and antiviral treatments were added. We successfully treated a patient with HSV-1 keratitis who was misdiagnosed due to clinical features and IVCM findings similar to fungal keratitis. The patient's infection was controlled. At 2 years after surgery, the cornea recovered well. HSV-1 keratitis with atypical clinical presentation can be easily misdiagnosed. This case report emphasizes the importance of NGS in diagnosing the pathogens of keratitis.