LAUSR

PURPOSE To investigate the choriocapillaris and choroidal characteristics of focal choroidal excavation (FCE) in order to establish pathomechanisms of the disease. METHODS 30 eyes with FCE, 27 eyes with pachychoroid neovasculopathy (PNV) and 25 participants without any conditions (control group) were analyzed retrospectively. The thickness of both choriocapillaris-equivalent and whole choroid was measured at three different points: under the lesion (excavation or neovascularization), in the normal retina, and in the fovea of fellow eye. Indocyanine green angiographs (ICGA) were collected to confirm choriocapillaris ischemia and choroidal inflammation presence. RESULTS In both FCE and PNV, choriocapillaris-equivalent attenuation was observed under the lesion compared to other region of the retina (28.1±11.3µm vs 69.4±20.0µm in FCE; 23.5±9.7µm vs 62.3±14.7µm in PNV; both p<0.001). We also observed focal thinning of the whole choroid under the lesion (149.7±88.7µm vs 296.6±83.2µm, p<0.001) in FCE, but not in PNV. Pachy-vessels distribution on OCT and numerous dark areas on ICGA implied that choroidal inflammation was related to the FCE occurrence. CONCLUSION Choriocapillaris ischemia was related to both FCE and PNV. The choroidal thinning under the excavation and adjacent pachy-vessels observed in FCE suggested that focal inflammation and scarring may contribute to choriocapillaris ischemia and eventual retinal pigment epithelium retraction with dysfunction in the pathomechanism.