Purpose: To investigate the choriocapillaris and choroidal characteristics of focal choroidal excavation (FCE) to establish pathomechanisms of the disease.
Methods: Thirty eyes with FCE, 26 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 angiographic images were collected to confirm choriocapillaris ischemia and the presence of choroidal inflammation.
Results: In both FCE and PNV, choriocapillaris-equivalent attenuation was observed under the lesion compared with other region of the retina (28.1 ± 11.3 μm vs. 69.4 ± 20.0 μm in FCE; 23.5 ± 9.7 μm vs. 62.3 ± 14.7 μm in PNV; both P < 0.001). We also observed focal thinning of the whole choroid under the lesion (149.7 ± 88.7 μm vs. 296.6 ± 83.2 μm; P < 0.001) in FCE but not in PNV. Pachyvessels distribution on optical coherence tomography and numerous dark areas on indocyanine green angiography 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 pachyvessels 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.