Current concepts in pachychoroid spectrum diseases: insights into the pathophysiology

The pachychoroid spectrum defines a group of diseases in which focal or diffuse thickness increase in the choroid layer is accompanied by dilated outer choroidal vessels and structural changes in the inner choroidal layers associated with it. This spectrum of diseases includes pachychoroid pigment epitheliopathy, central serous chorioretinopathy, pachychoroid neovasculopathy, polypoidal choroidal vasculopathy, focal choroidal excavation, peripapillary pachychoroid syndrome, and pachydrusen. Although these diseases have similar pachychoroid features, they have different clinical prognosis, ranging from a completely asymptomatic course to a very resistant clinical situation. The aim of this review is to summarize the current definition, underlying etiopathogenesis, examination findings, imaging features, differential diagnoses, and treatment approaches in light of current literature.