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Choroidal changes have been suggested to be involved in the pathophysiology of both age-related macular degeneration (AMD) and pachychoroid spectrum diseases (PSD). To find out the choroidal characteristics of each disease groups, various groups of AMD and PSD were classified into several clusters according to choroidal profiles based on subfoveal choroidal thickness (CT), peripapillary CT, the ratio of subfoveal CT to peripapillary CT and age. We retrospectively analyzed 661 eyes, including 190 normal controls and 471 with AMD or PSDs. In the AMD groups, eyes with soft drusen or reticular pseudodrusen were belonged to the same cluster as those with classic exudative AMD (all p < 0.001). However, eyes with pachydrusen were not clustered with eyes from other AMD groups; instead, they were classified in the same cluster as eyes from the PSD group (all p < 0.001). In the PSD group, eyes with pachychoroid neovasculopathy were grouped in the same cluster of those with polypoidal choroidal vasculopathy (p < 0.001). The cluster analysis based on the CT profiles, including subfoveal CT, peripapillary CT, and their ratio, revealed a clustering pattern of eyes with AMD and PSDs. These findings support the suggestion that pachydrusen has the common pathogenesis as PSD.

Enhanced depth imaging optical coherence tomography (EDI-OCT) and swept-source OCT (SS-OCT) have emerged as essential diagnostic tools in the study and management of various chorioretinal diseases. Evidence from early clinical studies using EDI-OCT and SS-OCT indicates that choroidal dysfunction plays a major role in the pathogenesis of chorioretinal diseases. Measurement of choroidal thickness (CT) has already become a major research and clinical method, and CT is considered as an indicator of choroidal status in a variety of ophthalmic diseases. Recently, CT measurement has also been proposed as a non-invasive marker for the early detection and monitoring of various systemic diseases. Among the several possible CT measurement locations, subfoveal CT has rapidly become a reliable parameter for measuring CT in healthy and diseased eyes. Moreover, recent advancements in OCT technology have enabled faster and wider imaging of the posterior part of the eye, allowing the various changes in CT as measured outside the macula to be shown accordingly. In this review, we first provide an overview of the results of clinical studies that have analyzed the healthy macular choroid and that in various chorioretinal diseases, and then summarize the current understanding of the choroid outside the macula. We also examine the CT profile as an index that encompasses both within and outside of the macula. Furthermore, we describe the clinical applications of ultrawide OCT, which enables visualization of the far periphery, and discuss the prospects for the development of more reliable choroidal parameters that can better reflect the choroid's characteristics.

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To investigate choroidal vascularity outside the macula in central serous chorioretinopathy (CSC).Methods: Fifty normal controls and 103 patients with a history of CSC (31 with acute CSC, 32 with chronic CSC, and 40 with resolved CSC) were included. Using swept-source optical coherence tomography, we measured choroidal thickness (CT) and choroidal vascularity index (CVI) at the subfoveal and nasal peripapillary areas.Results: Subfoveal CT in the acute CSC group was greater than that in all other groups (all P < 0.05). Peripapillary CT in the acute and chronic CSC groups was significantly greater than that in controls (all P ≤ 0.005). However, subfoveal and peripapillary CT in the resolved CSC group was not different from controls. Subfoveal CVI in the acute group (64.71% ± 2.68%) was higher than that in controls (61.68% ± 5.68%) (P = 0.015). Peripapillary CVIs in the acute (67.35% ± 6.04%) and chronic groups (64.90% ± 5.31%) were higher than controls (54.57% ± 7.02%) (all P < 0.001). Subfoveal CVI in the resolved CSC group was not different from controls (P = 0.252), whereas peripapillary CVI (62.61% ± 6.03%) was higher (P < 0.001).Conclusions: Unlike CT, CVI outside the macula was increased in all eyes with both current and past history of CSC. These findings suggest that the choroidal vascularity outside the macula may represent choroidal characteristics in addition to the subfoveal area.Translational Relevance: Peripapillary CVI outside the macula may provide additional information beyond what is known through subfoveal choroid studies.