By comparing the phenotype of a PCV mouse model expressing protease high temperature requirement factor A1 (HTRA1) in retinal pigment epithelium with transgenic mice expressing the inactive HTRA1<sup>S328A</sup>, we showed that HTRA1-mediated degradation of elastin in choroidal vessels is critical for the development of PCV, which exhibited destructive extracellular matrix remodeling and vascular smooth muscle cell loss.