Competitive quenching: a possible novel approach in protecting RPE cells from damage during PDT.

Purpose: The purpose of this study is to demonstrate feasibility of using our novel concept, termed competitive quenching, for protecting the choroidal extravascular compartment and retinal pigment epithelium (RPE) from verteporfin (VP)-induced phototoxicity using hypericin. Furthermore, we aim to achieve partitioning of the quencher, hypericin, in the extravascular space and VP within the microvascular compartment of the chorio-retinal complex in vivo.

Methods: We protect RPE cells from damage inflicted by photoactivated VP by introducing hypericin into these cells prior to photosensitization to quench the photosensitizing activity of VP.