Cavity hyperreflective-content and septum's motion artifact in optical coherence tomography angiography

To characterize the cavity hyperreflective-content and septum's motion artifact (CHASMA) in en face optical coherence tomography angiography (OCTA) across multiple ocular fundus abnormalities.

This was a cross-sectional, observational study. Subjects with extravascular OCTA signals arising from the cavity's hyperreflective-content and/or septum were enrolled. Characteristics of en face OCTA images and corresponding cross-sectional optical coherence tomography (OCT) images were evaluated. CHASMA was classified according to anatomic location.

The images of 25 eyes from 25 subjects were analyzed. CHASMA was identified in particles within the vitreous cavity, intraretinal cyst, subretinal space and the pigment epithelial detachment (PED) cavities. The regions of CHASMA in all included OCTA images were associated with hyperreflective cavity content and/or intercavity septa on the corresponding structural OCT. CHASMA was classified as vitreous, intraretinal, subretinal and PED-CHASMA according to the anatomic locations. Fourteen eyes with vitreous opacities secondary to vitreous hemorrhage, vitreous floater were classified as vitreous CHASMA. Six eyes with cystoid macular edema and 1eye with sub-internal limiting membrane hemorrhage were classified as intraretinal CHASMA. Two eyes with subretinal hemorrhage or bacillary detachment were classify as subretinal CHASMA and 2 eyes with hemorrhagic PED were classified as PED CHASMA.

The cavities at different fundus levels may allow for macroscopic motion of the contents and intercavity septa, producing various motion artifacts. These motion artifacts are termed CHASMA and cautions should be taken when interpreting en face OCTA images.