Purpose: To subsegment the choroid in patients with polypoidal choroidal vasculopathy and to determine whether the ratio of choriocapillaris/Sattler layer thickness to total choroidal thickness is decreased at sites of polypoidal pathology.
Methods: Retrospective, observational, cross-sectional study. A total of 320 eyes of 305 patients with polypoidal choroidal vasculopathy were studied with optical coherence tomography and dye angiography. The ratio of choriocapillaris/Sattler layer thickness to total choroidal thickness was calculated at polypoidal lesion sites in eyes with subfoveal choroidal thickness (SFCT) ≤200 μm.
Results: Mean SFCT was 267.7 ± 118.5 μm for the entire cohort. Mean SFCT was 151.2 ± 35.0 μm in eyes with SFCT ≤200 μm (n = 124, 39%). In this subgroup, dilated Haller vessels (pachyvessels) were identified under the site of neovascular ingrowth in 117 eyes (94%). Choroidal thickness in the pachyvessel zone was greater (213.3 ± 52.2 μm) than SFCT (P < 0.001) with a significantly lower choriocapillaris/Sattler layer to total thickness ratio (P < 0.001). Qualitative alterations of the retinal pigment epithelium were observed in 60 eyes (51%).
Conclusion: Eyes with normal or subnormal SFCT exhibited extrafoveal choroidal thickening at sites of polypoidal disease. The choriocapillaris and Sattler layers were attenuated at these locations, but Haller vessels were markedly dilated. These changes were topographically associated with sites of neovascular ingrowth and support the classification of polypoidal choroidal vasculopathy as a pachychoroid disorder.