Fungal infections pose a significant threat to the visual system and associated neural structures. Key pathogenic fungi, such as Aspergillus and Mucorales, cause disease through mechanisms, including direct tissue invasion, critical angioinvasion leading to thrombosis and tissue necrosis, and perineural spread, with host factors like immunosuppression and diabetes mellitus significantly influencing susceptibility and clinical course. Orbital apex syndrome is a frequent and characteristic presentation, often accompanied by optic neuropathy and ocular motor cranial neuropathies. Accurate diagnosis relies on a high index of suspicion, supported by thorough clinical evaluation, advanced imaging techniques, and definitive histopathological confirmation via biopsy. Multiple biopsies and cultures are often needed due to patchy fungal invasion, and serologic tests can also support the diagnosis. Management requires a multidisciplinary approach, including surgical and antifungal therapy. Despite therapeutic advancements, early recognition and immediate, aggressive intervention are crucial for improving outcomes in these challenging and often lethal infections. This chapter provides a comprehensive review of their neuro-ophthalmological manifestations, with a particular focus on invasive fungal sinusitis that extends into orbital and intracranial regions.