Fungal Keratitis: A Narrative Review with a Focus on Antifungal Resistance and Emerging Therapies

Abstract:

Corneal infection that can cause blindness, fungal keratitis has shown an increasing prevalence worldwide, especially in tropical and subtropical areas, where it significantly increases the risk of unilateral corneal blindness. The epidemiology, molecular etiology, diagnosis, antifungal resistance, and changing treatment of fungal keratitis are all reviewed in this article. Geographic diversity is evident in epidemiological patterns, with filamentous fungi such as Aspergillus and Fusarium predominating in warm climes, and an increasing number of reports of Candida species in temperate and healthcare-associated settings. Disease incidence and outcomes have been further affected by post-COVID-19 changes in ophthalmic treatment, extensive corticosteroid exposure, delayed presentations, and environmental factors, including climate fluctuations and increased airborne spore loads. Rapid stromal invasion, enzyme-mediated tissue damage, biofilm development, and host immune dysregulation are key factors determining severity, according to molecular findings. For improved detection, including in culture-negative and polymicrobial cases, diagnostic advancements focus on combining traditional microscopy and culture with in vivo confocal microscopy, MALDI-TOF MS, targeted PCR, and metagenomic next-generation sequencing. Time to treatment is being reduced by rapid point-of-care techniques like tear β-D-glucan tests, LAMP, CRISPR/Cas platforms, and AI-based image analysis. The necessity for systematic susceptibility testing and antifungal management is supported by rising antifungal resistance, particularly rising MIC trends in Fusarium and Aspergillus species, which exhibit variable susceptibility to azoles and amphotericin B, highlighting the need for species-specific antifungal susceptibility testing. The evolving epidemiology, molecular etiology, and new developments in fungal keratitis diagnosis are covered in this article. Additionally, it emphasizes new therapeutic approaches, including advanced drug delivery systems, advances in antifungal resistance management, and potential avenues for improved management. The article presents a narrative review focusing on recent developments in the epidemiology, molecular mechanisms, diagnosis, antifungal resistance, and treatment options for fungal keratitis.