A 68-year-old Korean woman with a history of hypertension and type 2 diabetes mellitus suddenly began to see strange apparitions in her left visual field. These visions consisted of a white tumbler and a woman wearing white clothes. At first, these visual hallucinations appeared only on rare occasions, but the duration and frequency of the hallucinations increased over time. At times, she also saw visions of a short boy holding a duster. These visions always appeared in the left visual field. Whenever she looked to the left, the hallucination moved to the far left side and decreased in size. Because the symptoms persisted, the patient sought the assistance of an exorcist after 1 month. After the first exorcism, the visions of the tumbler-shaped object and woman wearing white clothes disappeared. However, she began to have visions of a black snake and these visions occurred less frequently than the former objects. After 3 weeks, the patient again received help from the exorcist because of the apparent effectiveness of the first exorcism. However, after the second exorcism, the black snake became enlarged and changed into a blue monster with a mustache. Three months after the onset of these symptoms, the patient was admitted and assessed. On neurologic examination, her consciousness was clear, and her visual acuity and color vision were all normal. Goldmann perimetry showed complete left hemianopsia with homonymous right inferior partial quadrantic defects adjacent to the vertical meridian (Fig. 1A). Brain fluid-attenuated inversion recovery (FLAIR) images demonstrated an old infarction in the right occipital lobe and an ischemic lesion in the left cuneus (Fig. 1B). Cognitive function was completely normal, and the patient did not take any medication other than for hypertension and diabetes. There were no abnormalities in the laboratory evaluation performed at the early stage of hospitalization. There was no evidence of central nervous system infection. In addition, no significant epileptiform discharge was shown in the initial electroencephalography (EEG). The patient was started on olanzapine at a dose of 10 mg/day. A few days later, the frequency of the visual hallucinations was remarkably reduced, and she was discharged ten days after admission. However, the visual hallucinations continued to appear on rare occasions 6 months after her initial admission.

A 68-year-old Korean man developed complex visual hallucinations in the right visual field. These hallucinations included images of strange plants that had green leaves and white flowers. These plants persistently appeared in his right visual field and decreased in size whenever he looked to the right side. The patient was admitted and assessed 3 days after the onset of these symptoms. The patient had no history of previous neurological or psychological disorders. Baseline laboratory tests were normal. On neurologic examination, his consciousness was clear, and his visual acuity and color vision were normal. Humphrey perimetry revealed right congruent homonymous hemianopsia (Fig. 2A). There were no other sensory or motor deficits. Diffusion and FLAIR images obtained 3 days after symptom onset showed hemorrhagic transformation of acute bilateral ischemic lesions in the occipital lobes (Fig. 2B). Initial EEG did not show a significant epileptiform discharge. Although without specific medical treatment, all of the hallucinations completely disappeared 7 days after the first hallucination, with the right congruent homonymous hemianopsia remaining unchanged.