Is there any relationship between photodynamic therapy for exudative age-related macular degeneration and choroidal neovascularization recurrence? A rationale for combined treatments

Purpose. Photodynamic therapy (PDT) is the treatment of choice for subfoveal choroidal neovascularization (CNV) in age-related macular degeneration (ARMD). Interpretation of PDT mechanism of action is not yet fully understood and causes of CNV recurrences are unclear. The authors have conducted a retrospective analysis of fluorescein and indocyanine green angiographies in patients treated with multiple PDT in order to identify risk factors for recurrence. Methods. A total of 342 eyes of 342 patients (207 women and 135 men) with ARMD and subfoveal CNV were treated with at least two PDT. Angiographic (fluorescein and indocyanine green) features of recurrences were confronted to pretreatment examinations in all patients. Results. Post-PDT angiographies showed in all eyes a dark circle corresponding to the laser spot even 1 year after treatment. Persistence or progressive regrowth of CNV developed in an area adjacent or corresponding to the original lesion, without any specific relationship with the location of fluorescein and indocyanine green late leakage or with presence of abnormal fluorescence due to pigment abnormalities. At the 3-month angiographic follow-up, 23 patients (6.7%) showed a recurrent CNV resembling shape and dimension of the laser spot used for the PDT treatment. Conclusions. The authors failed to identify angiographic signs helpful to predict the risk of CNV persistence or recurrence. PDT leaves minor but persistent changes in the choroidal vasculature within the treatment area. In some cases, the recurrent CNV seems to be related to the laser spot of the PDT.