Angiographic optical coherence tomography (OCT) of subretinal hyperreflective material (SHRM)

Abstract

Purpose : The range of SHRM in macular disease includes type 2 neovascularization (NV), fibrosis, subretinal hyperreflective exudate (SHE), acquired vitelliform lesions (AVLs) and hemorrhage. The prognostic significance of SHRM has been noted in clinical trials but discriminating SHRM subtypes requires multiple imaging modalities.
The purpose of this study is to describe angiographic OCT flow characteristics and artifacts in vascular and avascular SHRMs which may resolve differential diagnosis with a single scan.

Methods : Multicenter descriptive study. Patients were recruited with SHRM on cross-sectional OCT in the context of AMD, myopia, pachychoroid disease or macular dystrophy.
Clinical charts and multimodal imaging review established the SHRM subtype. Patients underwent angiographic OCT (RTVue XR, Optovue). Structural and angiographic OCT scans were examined together for i) intrinsic flow, ii) retinal projection onto the anterior surface of SHRM (strong, weak, absent), iii) retinal projection through SHRM onto pigment epithelium (RPE), iv) masking of choroidal flow by SHRM.

Results : Thirty eyes of 23 patients were included (type 2 NV: 4; SHE: 10; fibrosis: 4; AVL: 16; hemorrhage: 5; fibrin: 1). Mean age per eye was 76 years (SD: 12).
Intrinsic flow was strongest in Type 2 NV, capable of saturating the detection range. Subretinal fibrosis showed limited flow in residual trunk vessels and branches. Flow was not detected in SHE, hemorrhage or vitelliform lesions. Retina→SHRM surface projection was strongest onto fibrosis and hemorrhage, weak onto SHE, fibrin and amorphous AVLs, and almost absent on granular AVLs. Retina→RPE projection was strong/weak through SHE (thickness dependent), weak through hemorrhage and absent through fibrosis. Subretinal fibrosis and granular AVLs masked the choroid. Projection characteristics of type 2 NV were difficult to assess.
In eyes with multiple SHRM subtypes angiographic OCT features correlated spatially with multimodal imaging findings.

Conclusions : Angiographic OCT artifacts may be helpful in distinguishing SHRM components with differing composition, suggesting that it may be possible to discriminate SHRM subtypes using a single OCT device with angiographic processing. This study is limited by non-consecutive recruitment and unmasked grading but its findings are instructional for designing formal sensitivity/specificity analyses and reading center-based trials.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.