We read with great interest the article by Lee and associates comparing the efficacy of photodynamic therapy (PDT) with and without intravitreal bevacizumab (IVB) injections for the treatment of polypoidal choroidal vasculopathy (PCV). We were surprised to see only modest improvement in outcomes with the addition of vascular endothelial growth factor inhibition. Indeed, vascular endothelial growth factor inhibition has been used as an adjunct to PDT with great success in the treatment of neovascular age-related macular degeneration (AMD). We propose that perhaps Lee and associates did not achieve similar success in treating PCV because of the sequencing of their intervention regimen.
PCV and neovascular age-related macular degeneration are distinctly different disease entities. PCV is foremost a disease of the choroidal vasculature, whereas age-related macular degeneration is as a disease of the Bruch membrane and the retinal pigmented epithelium. Thus, the mechanism of subsequent choroidal neovascularization in the 2 diseases is not at all alike. We propose that perhaps the anomalous branching and polypoid vascular lesions of PCV ought to be exposed to PDT not 1 week after, but concurrently with, vascular endothelial growth factor inhibition. In this way, the causative vascular lesions are subjected to the cascade of oxygen radicals set in motion by PDT before they are sent into regression by bevacizumab. To this point, contemporary work has shown more favorable early outcomes when PDT and bevacizumab are administered only 1 day apart.
Additionally, bevacizumab administered simultaneously with PDT may treat not only neovascularization, but also complications occurring after PDT. Current literature supports a decrease in subretinal hemorrhage occurring after PDT when PDT is supplemented with bevacizumab. The half-life of bevacizumab in nonvitrectomized eyes has been documented to average only 4.32 days; therefore, 1 week between administrations of the 2 treatments would allow for too much washout to optimize treatment of complications occurring after PDT.
For these reasons, we believe further investigation into the combination of these 2 methods, specifically their timing, is necessary to optimize efficacy in treating PCV.