Pachychoroid disease spectrum: how multimodal imaging and OCT angiography have improved our knowledge

Pachychoroid spectrum disorders (PSDs) represent a group of chorioretinal disorders characterized by abnormal choroidal thickening and various pathological changes in the choroid, retinal pigment epithelium, and retina. This review provides a comprehensive analysis of current multimodal imaging techniques in the diagnosis and management of PSDs. We examine the role of various imaging modalities including optical coherence tomography (OCT), OCT angiography (OCTA), en face OCT, fluorescein angiography (FA), indocyanine green angiography (ICGA), infrared imaging (IR), and fundus autofluorescence (FAF) in evaluating PSDs. Each imaging modality provides unique insights: OCT reveals characteristic choroidal thickening and structural changes; OCTA demonstrates alterations in choroidal flow and neovascularization; en face OCT allows detailed visualization of choroidal vasculature and intervortex anastomoses; FA shows patterns of leakage; ICGA reveals choroidal hyperpermeability and pachyvessels; IR imaging assists in RPE evaluation; and FAF highlights RPE dysfunction. The integration of these imaging techniques has enhanced our understanding of the pathophysiology of PSDs and improved our ability to diagnose, monitor, and treat these conditions. This review particularly emphasizes how OCTA has advanced our knowledge of choroidal circulation and neovascularization in PSDs. We also discuss future directions in imaging technology and their potential impact on personalized therapeutic approaches, including optimized photodynamic therapy based on imaging biomarkers. The synergistic use of multimodal imaging represents a cornerstone in the management of PSDs, enabling more precise diagnosis and tailored treatment strategies.