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Akihito Uji, Nagahisa Yoshimura; The Application of Extended Field Imaging to Optical Coherence Tomography. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):594.
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© ARVO (1962-2015); The Authors (2016-present)
To report and examine a novel technique that applies wide-field imaging to existing optical coherence tomography (OCT) systems. Both spectral domain and swept source OCT imaging systems were evaluated.
Ten healthy subjects with normal eyes were recruited into the study. Horizontal and vertical line scans through the fovea were acquired from all subjects with conventional OCT (Spectralis® OCT and DRI OCT-1) and with a novel extended field imaging (EFI) OCT technique. Various other commercially available OCT systems (RS3000 [Nidek], Cirrus HD-OCT [Carl Zeiss Meditec], RTVue-100 [Optovue], and 3D OCT-2000 [Topcon]) were used to image the eye in one subject for comparison. Differences in scan length measurements between conventional imaging and EFI OCT were analyzed. A model eye (developed by Canon, Inc.) with known dimensions was also imaged using the EFI technique. Scan length and image distortion in both horizontal and vertical scans were measured.
Average horizontal and vertical scan length measured 9416 ± 410μm and 9437 ± 374μm, respectively, on Spectralis® OCT scans. When EFI was used with this device, the average horizontal and vertical scan length significantly increased to 13,610 ± 843 μm and 14,082 ± 701 μm, respectively (both P < 0.0001). Average horizontal and vertical scan length both measured 12,729 ± 680 μm on DRI OCT-1 images. When EFI was used with this device, horizontal and vertical scan length increased to 20,745 ± 1738 μm and 21,467 ± 2478 μm, respectively (both P < 0.0001). Actual model eye dimensions (marked by scale reflections) and scan length measurements (measured in pixels) were both linear correlated, indicating that little image distortion occurred during EFI OCT imaging. In one subject, the EFI technique was successfully used with all examined OCT systems, and resulted in an increased scan length in all systems.
The EFI technique enables OCT imaging of a wider field than is possible with conventional OCT imaging. This technique is easy to implement and can be applied to a variety of OCT systems.
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