RESUMO
Photodynamic therapy (PDT) with verteporfin is a 2-step procedure that involves the infusion of phtosensitizing drug (verteporfin) followed by activation of the drug using a low density ("cold") laser at a wavelength of 689 nm. Once activated, free radicals are generated and cause thrombosis within the neovascular tissue and surrounding choriocapillaris. However, within 3 months, the neovascularization tends to recur in most patients and additional treatments are necessary to preserve vision and contain the growth of the neovascular lesion. PDT with verteporfin has been shown to be safe and effective for the treatment of choroidal neovascularization. The benefits of verteporfin therapy have been proven in several multicentre placebo controlled double-masked clinical trials. The treatment of Age-related Macular Degeneration with Photodynamic Therapy (TAP) investigation demonstrated that verteporfin therapy could prevent moderate visual loss, preserve contrast sensitivity, and contain lesion growth in subjects with predominantly classic choroidal neovascularization (CNV). This treatment benefit was observed at one-year and was sustained at 3 years. Another study known as the VIP Trial (Verteporfin In Photodynamic Therapy) demonstrated that verteporfin therapy was beneficial in patients with AMD and occult neovascularization. Another treatment arm of this same study demonstrated a treatment benefit for patients with pathologic myopia and CNV. Finally, in a small open-label study of patients with occular histoplasmosis and CNV known as the VOH (Verteporfin in Ocular Histoplasmosis) Study, verteporfin therapy was found to result in overall visual improvement . Additional studies are ongoing to improve this therapy and broaden the indications for use in all patients with CNV. (AU)
