Age-related macular degeneration (AMD) represents the most common cause of blindness in patients over the age of 60. The major cause of vision loss in this disease is due to the development of choroidal neovascularization. Several clinical trials have shown that eyes with predominately 'well-defined' areas of neovascularization (lesions having at least 50% of vessels which can be readily demarcated with fluorescein angiography) can benefit from treatment with photodynamic therapy (PDT). However, this treatment benefit only results in a reduction in the number of patients who suffer severe vision loss. Few patients demonstrate an improvement in visual acuity. In addition, other neovascular lesions such as those with predominate occult (vessels that are difficult to outline by fluorescein angiography) or pure occult do not demonstrate any substantial treatment benefit.