Controversies and conundrums in pachychoroid spectrum disorders: A structured diagnostic approach

The term pachychoroid, derived from the Greek word pachy meaning "thick," refers to a choroidal phenotype characterized by increased choroidal thickness, dilated outer choroidal vessels (pachyvessels), and attenuation of the overlying Sattler layer and choriocapillaris. Initially recognized in central serous chorioretinopathy, this phenotype is now acknowledged as the underlying pathophysiological basis for a broader spectrum of retinal disorders, including pachychoroid pigment epitheliopathy, pachychoroid neovasculopathy, polypoidal choroidal vasculopathy, focal choroidal excavation, peripapillary pachychoroid syndrome, pachydrusen and pachychoroid geographic atrophy. Collectively referred to as the pachychoroid disease spectrum, these entities share common features such as structural choroidal remodeling, choroidal vascular hyperpermeability, and outer retinal or retinal pigment epithelial changes. The introduction of enhanced depth imaging and swept-source optical coherence tomography (OCT), OCT angiography, and ultra-widefield indocyanine green angiography has significantly expanded the understanding of choroidal anatomy and function, leading to the identification of additional features such as vortex vein abnormalities, intervortex venous anastomoses, and localized choroidal hypoperfusion. These insights have prompted a reevaluation of disease classification. Moreover, pachychoroid-driven neovascularization demonstrates distinct therapeutic behaviour, including variable responses to anti-vascular endothelial growth factor agents and potential benefit from photodynamic therapy. We explore current controversies related to the etiopathogenesis, disease classification, and treatment of pachychoroid disorders, emphasize the importance of multimodal imaging in accurate diagnosis, and propose a clinically relevant algorithm to help ophthalmologists identify and manage true pachychoroid spectrum disorders effectively.