Pachychoroid spectrum diseases includes central serous chorioretinopathy (CSC), pachychoroid pigment epitheliopathy, pachychoroid neovasculopathy, and polypoidal choroidal vasculopathy, which share common characteristics, including focal or diffused increased choroidal thickness, choroidal hyper-permeability, and dilated choroidal vessels. These diseases are likely to represent a continuum of the same pathogenic process. Similar features and association among them suggest that they may have similar etiology. It is of great clinical significance to understand the composition and typical morphological changes of pachychoroid-related diseases and to explore its possible pathogenesis.