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Reza Motaghiannezam, Florian M. Heussen, Srinivas R. Sadda, Scott E. Fraser; Non-invasive Intensity-based Motion Contrast Swept Source Optical Coherence Tomography For In Vivo Visualization Of The Human Retinal Microvasculature. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2197.
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© ARVO (1962-2015); The Authors (2016-present)
To validate a novel intensity-based motion sensitive method, called differential logarithmic intensity variance (DLOGIV), for 3D microvasculature imaging and foveal avascular zone (FAZ) visualization in the in vivo human retina using swept source optical coherence tomography (SS-OCT) at 1060 nm.
A motion sensitive SS-OCT system was developed operating at 50,000 A-lines/s with 5.9 µm axial resolution, and used to collect 3D images over scanning angles of ~6 degrees* 6 degrees. Multiple B-scans were acquired at each individual slice through the retina and the variance of differences of logarithmic intensities as well as the differential phase variances (DPV) were calculated to identify regions of motion (microvasculature). En face images were generated for qualitative and quantitative assessment of the FAZ in four eyes of two normal subjects, and fluorescein angiography (FA) was performed for subsequent comparison.
En face DLOGIV images were capable of capturing the microvasculature through depth with an equal performance compared to the DPV. The sensitivity and resolution of parafoveal capillary meshwork images from both DLOGIV and DPV were significantly greater than FA images of the same regions (Figure 1). While DLOGIV, DPV and FA captured and quantified FAZs in two eyes of one healthy subject (Figures 1(c,e,g)), no FAZ was discernible in either eye of the other healthy subject (Figures 1(d,f,h)).
We could prove the feasibility of a novel imaging method (DLOGIV) for non-invasive, dye-free visualization and quantification of the retinal microvasculature using a SS-OCT at 1060nm. Compared to DPV, DLOGIV does not rely on phase information. Therefore, it is less sensitive to the phase instability of the system and environment, and there is no need for phase compensation algorithms and additional optical modules. As such, DLOGIV may be advantageous to both DPV and invasive FA for imaging the retinal microvasculature and be a helpful diagnostic tool in the future.
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