Purchase this article with an account.
Erqian Wang, Youxin Chen; Comparing SS-OCTA and En-face OCT Images of the Choroid in Macular Area of Healthy Human Eye. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2879.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Optical Coherence Tomography Angiography (OCTA) of the deep choroid has rarely been utilized in clinical practice. Uncertainty remains in interpretation of images due to the complexity of choroid vasculature and the difficulty in visualizing deep intravascular flow. The study compared cross-sectional swept source OCTA and en-face OCT images of choroid in healthy human macula, aiming to find clues in interpretation of choroid OCTA images.
Healthy volunteers were recruited for SS-OCTA (DRI Triton plus, Topcon) scanning with macula 3.0*3.0mm protocol, and subjects with adequate image quality were included for further analysis. OCTA and en-face OCT cross-sectional images were generated in pair at fixed or percentile depth of the choroid, from choriocapillaris to outer choroid. We then compared each pair of binarized OCTA and en-face OCT images and calculated similarity index (SI) which was defined as the ratio of the number of pixels with the same color in two images to the total number of pixels.
Images from 41 eyes of 29 persons were analyzed. OCTA images showed black signal pattern which was similar with the dark grey signal pattern of vessel lumen in en-face OCT (Figure 1). When searching through choroid at fixed depth, the peak of SI between OCTA and en-face OCT images was 82.3±2.5% at around 98.9μm beneath Bruch membrane (BM) (Figure 2A). After stratifying all subjects with central choroid thickness (CCT), the peaks of SI were over 80% at around 98.9μm beneath BM in all subgroups. When searching through choroid at percentile depth, the peak of SI was 78.3±5.0% at around 25.0% CCT beneath BM (Figure 2B). After stratifying with CCT, the peak of SI was at around 75.0% CCT, 50.0% CCT, 25.0% CCT, 16.7% CCT beneath BM in subjects with a CCT of 100-199μm, 200-299μm, 300-399μm, and 400μm or more, respectively.
Choroid cross-sectional OCTA images showed similar pattern with those of en-face OCT, especially at around a hundred micrometers beneath BM. OCTA images might be useful in depicting choroid vasculature.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Macular OCTA and en-face OCT images of a 51 year-old female at 98.9μm beneath Bruch membrane. 1a, raw OCTA; 1b, raw en-face OCT; 1c, binarized OCTA; 1d, binarized en-face OCT; 1e, combined similarity map.
Similarity Index of OCTA and en-face OCT at different depth of choroid: 2a, fixed depth; 2b, percentile depth.
This PDF is available to Subscribers Only