Visual hallucinations and Charles Bonnet syndrome after photodynamic therapy for age related macular degeneration.

AIMS: To report on visual hallucinations and Charles Bonnet syndrome (CBS) that may occur in patients with age related macular degeneration (AMD) treated by photodynamic therapy (PDT) with verteporfin for choroidal neovascularisation (CNV). METHODS: 100 consecutive patients were asked to respond to an orally administered questionnaire on visual hallucinations following PDT. Three groups of patients, respectively without visual hallucinations, with unstructured visual hallucinations, and with structured hallucinations-that is, CBS, were compared by ANOVA, Scheffe's test, or the chi(2) test, to establish whether age, sex, or visual acuity, as scored on ETDRS charts, are risk factors for the occurrence of visual hallucinations. RESULTS: Five patients (5%) described transient structured visual hallucinations, including known or unknown faces and geometric patterns. Fifteen patients (15%) reported photopsias and flashing lights of various colours. These symptoms usually occurred a few days after PDT. There was no significant difference between the group of patients with structured visual hallucinations and the two other groups, with regard to age (p =0.435), sex (p =0.406), or visual acuity (p =0.835). CONCLUSIONS: Visual hallucinations and CBS appear to be a possible, although unrecognised, side effect of PDT for CNV, which occur just after treatment. These results suggest the need to include the possibility of visual hallucinations in the information given to patients before PDT.