This paper presents a literature review and a case of an 83-year-old otherwise healthy female patient with a history of recent syncope, a sudden-onset right-sided temporal headache, diplopia, and vision loss. An exam revealed right-sided upper eyelid ptosis, myosis, vision loss, ophthalmoplegia, and a positive relative afferent pupillary defect on the right eye. CT showed sphenoid sinus opacification, eroded lateral sinus wall, Vidian canal, disease extension to the posterior ethmoid air cells, orbital apex, medial orbital wall, and pterygopalatine fossa. An orbital apex syndrome (Jacod’s syndrome), Horner syndrome, and pterygopalatine fossa infection were diagnosed due to the acute invasive fungal sinusitis developed from a sphenoid sinus fungal ball. The patient was treated with antimicrobial therapy and transnasal endoscopic surgery twice to decompress the orbital apex, drain the abscess and obtain specimens for analysis. The right-sided ptosis, visual loss, ophthalmoplegia, and headache resolved entirely. No immune or comorbid diseases were identified, microbiological and histopathological analyses were negative, and MRI could not be performed on the presented patient. For that reason, the diagnostic procedure was non-standard. Nevertheless, the treatment outcome of this vision and life-threatening disease was satisfactory. Treating the fungal ball in an older or immunocompromised patient is essential to prevent invasive fungal rhinosinusitis and fatal complications.