Analysis of choroidal morphology and comparison of imaging findings of subtypes of polypoidal choroidal vasculopathy:a new classification system

摘要

AIM:To classify polypoidal choroidal vasculopathy(PCV)into 2 subtypes based on the subfoveal choroidal thickness(SFCT)and to further evaluate their multimodal image features.METHODS:A retrospective observational case series study.Sixty-four eyes of 64 patients with PCV were enrolled and classified into 2 groups based on SFCT(thick-choroid group/thin-choroid group).Then further analyze the spectrum domain optical coherence tomography(SD-OCT)and indocyanine green angiography(ICGA)differences of the two subtypes.Imaging analysis included measurement of SFCT,maximum vascular diameter ratio(MVDR),choroidal vascularity index(CVI),central macular thickness(CMT),and the presence of pigment epithelial detachment(PED)on SD-OCT.Polypoidal lesions(polyps)number,branching vascular network(BVN)area,greatest linear dimension(GLD),and the choroidal vascular hyperpermeability(CVH)were analyzed by ICGA.RESULTS:The distribution of SFCT was bimodal with two peaks at 195 and 285μm,and a trough at 225μm.The 225μm was taken as the cutoff point for the following classification of thick/thin choroid groups.The PCV eyes in the thick-choroid group presented with greater MVDR,CVI within 3 and 6 mm of the fovea,but lower CMT,less PED,small PED diameters on SD-OCT scans,and fewer polyps,smaller BVN and GLD,but more frequency of CVH on ICGA.CONCLUSION:The SFCT at 225μm can be used as a readily available indicator for the classification of PCV subtypes.The thick-choroid group presents much apparent enlargement of the choroidal layer and vasculature expansion,which indicates different pathogenesis of the two subtypes.