Choriocapillaris Island: an optical coherence tomography angiography finding observed in central serous chorioretinopathy

Abstract

Purpose: To report the observation of the choriocapillaris island (CCI) on optical coherence tomography angiography (OCTA) in eyes with active central serous chorioretinopathy (CSCR), and to investigate its associated clinical features.

Design: Retrospective observational study.

Methods: Patients diagnosed with active CSCR underwent OCTA imaging (Optovue Inc, Fremont, California, USA), and the software built-in en face choriocapillaris slab was examined to demonstrate CCI, defined as an area of detectable choriocapillaris flow surrounded by an area of undetectable or diminished flow. Electronic medical records (EMR) were reviewed for demographics, clinical data, other imaging modalities and any intervention, and these parameters were correlated with CCI findings.

Results: 25 eyes of 25 patients were recruited. CCI was detected in all examined eyes and was best elucidated on the en face choriocapillaris density maps. 24 eyes had focal retinal pigment epithelium (RPE) alterations overlying CCI. All 14 eyes with simultaneous fundus fluorescein angiography (FA) showed actively leaking point(s) well corresponding to the CCI location. Resolution of sub-retinal fluid in 4 eyes was associated with disappearance of CCI on follow-up OCTA scans. 1 eye showed complicating neovascularization 5 months after the initial presentation at the same location of the CCI.

Conclusion: We demonstrate the observation of the "choriocapillaris island" an OCTA finding in eyes with active CSCR underneath the area of neurosensory detachment. CCI may constitute an angiographic representation of the focal area of choriocapillaris structural and functional affection, with secondary RPE alteration jeopardizing its barrier function. Larger longitudinal studies are needed to further elucidate this finding.

Keywords: Central serous chorioretinopathy; Choriocapillaris; Optical coherence tomography angiography.

Fig. 1.

Demonstration of the choriocapillaris island(CCI) on optical coherence tomography angiography (OCTA). a 3 × 3 en face choriocapillaris OCTA showing central diminished flow underneath the area of neurosensory detachment except for a focal area (yellow circle)showing localized detectable flow, ie: the “choriocapillaris island”. b Choriocapillaris density map of the same area showing central signal attenuation represented in blue and an inferonasal juxta foveal CCI (yellow circle). c Corresponding B scan with angio-overlay showing diminished choriocapillaris flow (between red lines) underneath sub-retinal fluid except for a focal area (yellow circle) showing signal enhancement

Fig. 2.

A representative example of image correlation obtained by different imaging modalities from the same patient by aligning retinal blood vessels to display the CCI location in relation to the leaking point(s)on fluorescein angiography (FA) and corresponding structural changes on optical coherence tomography angiography (OCT). a Superimposition of the 3 × 3 OCTA density map and the scanning laser ophthalmoscopy (SLO) OCT on FA images. b FA shows superonasal parafoveal leaking points, the area scanned by OCT (white rectangle) and the area scanned with OCTA (yellow rectangle). c Superimposition of the (SLO-OCT)image on FA image and orientation of the OCT line scan passing through leaking points (green arrow). d Superimposition of 3 × 3 OCTA density map image on FA image to display CCI location in relation to the leaking points. e Enhanced depth imaging (EDI) OCT line scan showing focal RPE alterations with underlying pachy choroidcoinciding with CCI location on density map and leaking points on FA (yellow oval)

Fig. 3.

A patient showing spontaneous resolution of sub-retinal fluid within 2 months of the initial presentation. a FA showing superonasal a juxta-foveal actively leaking point (yellow arrow) and the area scan by OCTA (yellow rectangle). b 6 × 6 OCTA density map of the choriocapillaris slab at the initial presentation showing central signal void area represented in blue color and a superonasal juxta foveal choriocapillaris island (CCI) corresponding to the same location the leaking point on FA. c Follow-up OCTA density map showing relative restoration of the choriocapillaris flow with disappearance of CCI. d 6 × 6 en face choriocapillaris OCTA at the initial presentation showing CCI (yellow arrow). e Follow-up en face OCTA showing relative restoration of choriocapillaris flow. f B scan corresponding to the angiogram in D showing focal retinal pigment epithelium (RPE) changes with bridging of retinal layers(yellow arrow) coinciding with CCI. g Follow-up B scan corresponding to the angiogram in e

Fig. 4.

A patient showing complicating neovascularization 5 months after the initial presentation. a FA at the initial presentation showing superonasal para-foveal actively leaking points, the area scan by (OCTA) (yellow rectangle) and enhanced depth imaging OCT (EDI-OCT) line scan orientation (blue arrow). b EDI-OCT line scan at the initial presentation showing focal double layer sign and underlying pachy-choroidal vessels (yellow oval) corresponding well to th leaking points on FA. c Follow-up EDI-OCT line scan showing formation of a shallow pigment epithelium detachment (PED) with underlying pachy-choroidal vessels and increased sub-retinal fluid. d 3 × 3 OCTA density map of the choriocapillaris slab at the initial presentation showing superonasal para-foveal CCI corresponding to the same location of leaking points on FA. e Follow-up OCTA density map. f 3 × 3 en face choriocapillaris OCTA at the initial presentation showing CCI location (yellow circle). g Follow-up en face OCTA showing development of choroidal neovascularization (CNV) at the same location. h B scan corresponding to the angiogram in F showing focal retinal pigment epithelium (RPE) changes coinciding with CCI. i, Follow-up B scan corresponding to the angiogram in g