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Shuichi Makita, Masahiro Miura, Shinnosuke Azuma, Toshihiro Mino, Tatsuo Yamaguchi, Yoshiaki Yasuno; High-density and >20-degree field-of-view en-face and three-dimensional posterior eye imaging by Lissajous scan optical coherence tomography and angiography. Invest. Ophthalmol. Vis. Sci. 2022;63(7):1055 – F0302.
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© ARVO (1962-2015); The Authors (2016-present)
Optical coherence tomography (OCT) and OCT angiography visualize in vivo human retina and its vasculature three-dimensionally with high-spatial resolutions. Involuntary eye movements make the trade-off between a field of view (FOV) and high-density sampling tight. We have developed a Lissajous scan OCT method that extends FOV with high-densely spatial sampling. The imaging capability of this method for diseased eyes is investigated.
A clinical prototype OCT device with a scan speed of 100,000 A-line/s is used. The OCT probe beam scans along with a modified Lissajous pattern. The continuous shifting of the Lissajous trajectory extends the FOV. Motion-free three-dimensional volumes and en-face OCT and OCTA images were generated by motion estimation and correction algorithms.Twelve eyes of 12 subjects with branch retinal vein occlusion (BRVO) were scanned. The scanning range exceeded around 22-degree in diameter. After motion correction, data are remapped in 812 x 812 grid points. Eyes were also scanned with a raster scan of 320 x 320 pixels, and 20-degree (6-mm) scanning size by a commercial OCTA device (DRI-OCT, Topcon).
Figure 1 shows en-face OCTA images of a representative case (79y, male). The en-face OCTA images of the superficial retinal slab with the Lissajous scan and the raster scan of the commercial device visualize the retinal vasculature. However, the enlarged images (the green box) show that the fine structure of retinal capillaries is visualized by the Lissajous scan method owing to high-spatial density. In 8 of 12 eyes, the capillaries around non-perfusion areas were better visualized.The en-face slice and cross-sectional images of another patient’s eye (76y, male) are shown in Figure 2. The distribution of cysts and abnormal blood flow patterns can be visualized in en-face and arbitrary cross-sectional images.
We have shown that the Lissajous scan OCT enables high-dense en-face and three-dimensional posterior eye imaging more than >20-degree FOV. This technique will enable the assessment of biomarkers in more detail with a large FOV.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
Fig. 1 En-face OCTA of a BRVO patient eye. The enlarged images show that high-density of Lissajous scan visualizes capillary vasculature well.
Fig. 2 En-face OCT and OCTA slices and the cross-section of OCT and OCTA of a BRVO patient eye.
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