Safety of verteporfin for treatment of subfoveal choroidal neovascular membranes associated with age-related macular degeneration

Photodynamic therapy (PDT) is a novel treatment entity that exploits the photophysical properties of various photosensitive chemical entities which, upon light activation, results in targeted photooxidation and subsequent tissue destruction. The antiangiogenic properties of PDT have been adapted for treatment of subfoveal choroidal neovascular membranes due to disease states such as age-related macular degeneration (AMD). Historically, PDT has been limited by a lack of suitable photosensitive dyes. However, agents such as verteporfin, a second-generation benzoporphyrin derivative, appear to be free from the extensive phototoxicity that limited the success of previous agents. Verteporfin has a high affinity for choroidal neovascular membranes, typically found with exudative AMD, and upon photoactivation results in targeted microvascular damage and thrombus formation with resultant vessel occlusion. Scrutiny of diagnostic indicators for verteporfin administration, including critical angiographic evaluation of lesion size and visual acuity, is essential to treatment success. Large lesions with relatively good visual acuity (20/50 or better) may be at particular risk for marked vision loss following verteporfin administration. Lesion composition also appears to influence visual outcome with verteporfin use. The safety of verteporfin is directly dependent upon the appropriate integration of dosage, infusion and light activation required for a suitable pharmacotherapeutic outcome. When used appropriately, and with adequate patient education regarding photosensitivity, the risk-benefit of verteporfin for the medical treatment of neovascular AMD is favourable.