We report the findings of single photon emission computed tomography using 123I-IMP and magnetic resonance image studies of five patients with Charles Bonnet syndrome (CBS) while they were having visual hallucinations. All patients developed complex visual hallucinations after suffering from eye disease. The mean age at onset of CBS was 71.6 years. Single photon emission computed tomography studies in all patients disclosed hyperperfusion areas with some asymmetrical appearances in the lateral temporal cortex, striatum and thalamus. These results suggest that when elderly people suffer from eye disease, subsequent excessive cortical compensation in the lateral temporal cortex, striatum and thalamus may precipitate the development of visual hallucinations.