Evaluation of Inner Choroidal Blood Flow in the Pachychoroid Spectrum Using Swept Source Optical Coherence Tomography Angiography

Abstract

Purpose : The pachychoroid spectrum encompasses various macular conditions including central serous chorioretinopathy (CSC), pachychoroid pigment epitheliopathy, pachychoroid neovasculopathy, and polypoidal choroidal vasculopathy. These conditions are characterized by retinal pigment epithelium (RPE) alterations over abnormally dilated outer choroidal vessels, termed pachyvessels. Attenuation of the inner choroid has been observed overlying these pachyvessels. This study aimed to characterize inner choriodal blood flow in patients with a history of CSC using swept source optical coherence tomography angiography (OCTA).

Methods : We performed a retrospective review of treatment-naïve patients with a history of CSC. Near-infrared reflectance images of the posterior pole were labelled for foci of inner choroidal thinning, which were identified on point-correspondent cross-sectional spectral domain optical coherence tomography (SD-OCT) scans. These manually prepared structural attenuation maps were registered and overlaid on OCTA inner choroidal flow density maps to assess spatial correlation between structural and flow attenuation. Confounding areas with RPE detachment, subretinal fluid (SRF), and/or RPE pigment clumps that might cause posterior shadowing were excluded from analysis.

Results : 18 eyes of 15 patients were included. Mean age of the subjects was 62 years and mean logMAR VA was 0.117 (SD=0.112). Discrete areas of inner choroidal structural attenuation were noted in all study eyes. All eyes exhibited various patterns of flow attenuation in areas not associated with SRF, PED or RPE pigment clumps. These areas of flow reduction included areas in which the overlying RPE and outer retina appeared normal on SD-OCT. Areas of reduced inner choroidal flow did not consistently correspond to areas of structural attenuation.

Conclusions : In eyes with a history of CSC, OCTA shows areas of inner choroidal flow reduction unexplained by signal attenuation from overlying PED, SRF, or pigment clumping. These areas of reduced flow show weak correspondence with areas of inner choroidal thinning seen on SD-OCT. While reduced inner choroidal flow may play a role in RPE alterations and subsequent neovascularization occurring in some eyes with chronic CSC and other pachychoroid spectrum disorders, inner choroidal thinning does not appear to be a reliable indicator of its presence.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.