The two biggest challenges for the widespread clinical use of the technology are the limited field of view (FOV) imaging capability and the sensitivity to eye motion artifacts. In addition, OMAG provides high-resolution depth sectioning capability for high-resolution microvascular visualization of the eye.Īlthough OMAG has demonstrated early clinical utility by imaging diseased eyes, it needs to overcome several technical challenges to be able to consistently provide useful, artifact-free and repeatable imaging performance. Hence, the attractiveness of using OMAG for vascular pathologies in the eye is further emphasized as it is a noninvasive imaging technique. However, the invasiveness of the dye injection combined with possible adverse reactions to the dye, such as nausea or anaphylactic response in some rare cases, makes it an unsuitable technique for frequent and widespread ophthalmic screening applications. 11, 12 FA and ICGA still remain the gold standards for diagnosis of any vasculature abnormality in the eye. 9, 10 OMAG has demonstrated clinical utility by imaging a range of retinal diseases including diabetic retinopathy and macular telangiectasia and drawing useful comparisons of imaging performances when compared with FA images. 8 OMAG has been applied to visualize high-resolution and high-contrast mapping of capillary networks in the retina and choroid. 6, 7 This measurement is less sensitive to the Doppler angle as experienced in Doppler-based flow measurement. OMAG-based OCT angiography is one of the leading techniques that is capable of providing the distribution of functional blood vessels including capillaries within tissue beds in vivo. OCT angiography, for example, optical microangiography (OMAG), 6, 7 has recently generated increasing interest in the OCT and ophthalmic research community. However, the traditional OCT technique is based on structural imaging, which gives limited functional information about the retina. While the clinical use of OCT has increased tremendously over the past decade, the use of traditional imaging strategies such as FA and fundus photograph have commensurately declined. In contrast to the currently available clinical imaging techniques such as fluorescein angiography (FA) and indocyanine green angiography (ICGA), OCT provides a noninvasive approach to rapidly assess three-dimensional (3-D) high-resolution microstructural information of the retina. The increased imaging speed and sensitivity of SD-OCT over time-domain OCT has produced its accelerated impact on retinal imaging. 3 Spectral domain OCT (SD-OCT) 4, 5 has been rapidly adopted and gained wide spread use in ophthalmic imaging applications, including both clinical and research. Over the last decade and a half, commercial ophthalmic OCT technology has advanced rapidly with continued improvements in the hardware, ease of use, and OCT data analysis features to aid in diagnostics or management of the progression of diseases. 2 Without a doubt, OCT has proved to be a disruptive technology in ophthalmology as it can provide unprecedented clinically useful information to aid the diagnosis and treatment of eye diseases. 1 The capability of OCT to provide noninvasive, noncontact, high-resolution, high-sensitive, and depth-resolved imaging of microstructures in the retina and eye has been a key factor for its success. Ophthalmic imaging has emerged as one of the most successful applications for optical coherence tomography (OCT) since its invention in the early 1990s. We experimentally demonstrate a 12 × 16 mm 2 retinal OMAG angiogram acquired from a volunteer, which is the widest FOV retinal vasculature imaging up to now in the community. Due to the robustness of the tracking LSO, we also show the montage scan protocol to provide unprecedented wide field retinal OMAG angiograms. We show that the tracking can effectively correct the motion artifacts and remove the discontinuities and distortions of vascular appearance due to microsaccade, leading to almost motion-free OMAG angiograms with good repeatability and reliability. The tracking LSO is able to guide the OCT scanning, which minimizes the effect of eye motion in the final results. Here, we report the results of retinal OMAG imaging obtained from a Zeiss Cirrus 5000 spectral domain OCT system with motion tracking capability achieved by a line scan ophthalmoscope (LSO). Although the technique has demonstrated early clinical utility by imaging diseased eyes, its limited field of view (FOV) and the sensitivity to eye motion remain the two biggest challenges for the widespread clinical use of the technology. Optical coherence tomography (OCT)-based optical microangiography (OMAG) is a high-resolution, noninvasive imaging technique capable of providing three-dimensional in vivo blood flow visualization within microcirculatory tissue beds in the eye.
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