ABSTRACT
Ocular photodynamic therapy (PDT) was introduced as effective treatment for neovascular forms of age-related macular degeneration (AMD) and choroidal neovascularization (CNV) secondary to pathologic myopia in the late 1990s. It is worth mentioning that verteporfin PDT (v-PDT) was the first approved therapy for the treatment of subfoveal lesions and, at that time, was the only solution to avoid progressive vision loss and blindness. Verteporfin, or benzoporphyrin derivative monoacid ring A (BPD-MA), is a second-generation lipophilic/amphiphilic photosensitizer (PS) with an absorption peak centered at 689 nm. It is administrated as a liposomal formulation called Visudyne (Novartis Pharmaceuticals), which is a mixture of the two regioisomers, each a racemic mixture of two enantiomers. Other PSs, such as hematoporphyrin derivative, were used in preclinical and clinical studies for ocular disorders with encouraging outcomes. These agents were later abandoned, however, due to their associated side effects and poor tissue penetration, and the search for new photosensitizers continued. Several other photosensitizers were tested in phase I/II clinical ophthalmological trials, including tin etiopurpurin (SnET2) and Lutetium texaphyrin (Lu-tex); however, they also failed to achieve market approval (Koh and Haimovici 2004).
