Rare Parasitic and Fungal Ocular Infections: Challenges in Diagnosis and Management

Background: Ocular infections of rare parasitic and fungal origin present a unique and formidable diagnostic and therapeutic challenge in ophthalmic medicine. These infections can pose challenging differential diagnoses for other ocular conditions, thereby causing delay in diagnosis and increased risk of visual loss. They are further complicated by antimicrobial resistance, limited treatment options, and prolonged treatment. Objective: This review describes rare parasitic and fungal ocular infections regarding their epidemiology, clinical features, diagnosis methods, and treatment options. We also discuss novel therapeutic strategies and advances in diagnostic methods. Methods: We conducted a systematic review of the existing literature to summarize the pathophysiology, clinical features, and management of fungal and parasitic infections of the eye. Novel diagnostic modalities including molecular assays, imaging modalities and artificial intelligence applications were also examined for their potential impacts on early diagnosis and treatment optimization. Results: Diagnosis of these infections requires a combination of slit-lamp biomicroscopy, microbiological culture, polymerase chain reaction (PCR) assays and imaging modalities. Although antifungal agents including natamycin, voriconazole and amphotericin B are the cornerstones of treatment for fungal infections, Acanthamoeba and other parasitic infections require longer courses of therapy with biguanides, diamidines and systemic antiparasitics. Recent innovations in nanoparticle-assisted drug delivery, photodynamic therapy, and gene-editing strategies have shown promise for improved clinical efficacy. Conclusion: Early diagnosis and appropriate management of rare parasitic and fungal ocular infections are essential for avoiding irreversible visual impairment. By incorporating new diagnostic technologies, tailored treatment regimens, and artificial intelligence-based diagnostic systems, the approach to these difficult pathogens could be transformed within the next few decades. More studies are needed to adapt treatment protocols and overcome treatment hurdles.