Orbital apex syndrome (OAS) is a localized orbital cellulitis at the orbital apex that can cause vision loss from optic neuropathy and ophthalmoplegia involving multiple cranial nerves. Herein, we report a rare and rapidly progressive case of OAS secondary to fungal pansinusitis caused by Scedosporiumapiospermum in an immunocompromised patient following the extraction of abscessed teeth. A 48-year-old man with diabetes mellitus who had failed to adhere to his treatment presented with complaints of a right-sided headache and toothache for two weeks, with nausea and vomiting for two days prior to presentation. The patient was treated for septic shock secondary to the dental abscesses. Non-contrast brain computed tomography (CT) showed no significant intracranial abnormalities other than pansinusitis. Four days later, dental extraction was performed. The patient reported progressive painless blurring of the vision in his right eye following the dental extractions and was referred to the ophthalmology department. Subsequent examinations revealed decreased optic nerve function and ophthalmoplegia in his right eye and dental caries in the upper molars, with a mucopurulent discharge from the right sphenoid region. The clinical diagnosis was OAS. Pus near the orbital apex was drained surgically. Methicillin-resistant Staphylococcus aureus was isolated from the pus and a nasal swab. Tissue culture from the septal wall yielded S.apiospermum. The patient's condition deteriorated, despite intensive antibiotic and antifungal treatment and repeated surgical debridement. The disease progressed rapidly to his left eye. Sixty-seven days after the inital presentation, his visual acuity (VA) of both eyes was classified as no perception of light (NPL). The patient discharged himself from the hospital (at own risk discharge) and subsequently failed to attend a scheduled appointment in the ophthalmology clinic. If immunocompromised patients present with OAS, fungal infections should be ruled out. Prompt and aggressive treatment using a multidisciplinary approach is mandatory in cases of potentially life-threatening and vision-threatening fungal infections.