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Human Parafoveal Capillary Vascular Anatomy and Connectivity Revealed by Optical Coherence Tomography Angiography

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      To assess the connection among arterioles, venules, and capillaries in three retinal capillary plexuses using optical coherence tomography angiography (OCTA).


      This was a prospective, cross-sectional, observational study including 20 eyes of 10 healthy subjects. En face and cross-sectional OCTA images were segmented to study the superficial (SCP), middle (MCP), and deep capillary plexuses (DCP). Using thin slabs and manual segmentation within the three plexuses, we examined the connections between the large-caliber superficial vessels within a 3 × 3 mm 2 OCTA scan (arterioles and venules) and the smaller capillaries in each plexus.


      Twenty eyes of 10 healthy subjects (5 females; average age of 30.8 ± 6.3 years) were included in the analysis. We identified vascular interconnections linking the superficial arterioles and venules with capillaries in each plexus (SCP, MCP, and DCP). We found capillaries in the DCP crossed the horizontal raphe.


      Our findings show that each of the three capillary plexuses in the parafovea has its own feeding arteriolar supply and draining venules, supporting a physiologic model in which each plexus controls its own oxygenated blood supply to match the metabolic needs of each distinct retinal neurovascular unit.

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      Most cited references 52

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      The Lens Opacities Classification System III. The Longitudinal Study of Cataract Study Group.

      To develop the Lens Opacities Classification System III (LOCS III) to overcome the limitations inherent in lens classification using LOCS II. These limitations include unequal intervals between standards, only one standard for color grading, use of integer grading, and wide 95% tolerance limits. The LOCS III contains an expanded set of standards that were selected from the Longitudinal Study of Cataract slide library at the Center for Clinical Cataract Research, Boston, Mass. It consists of six slit-lamp images for grading nuclear color (NC) and nuclear opalescence (NO), five retroillumination images for grading cortical cataract (C), and five retroillumination images for grading posterior subcapsular (P) cataract. Cataract severity is graded on a decimal scale, and the standards have regularly spaced intervals on a decimal scale. The 95% tolerance limits are reduced from 2.0 for each class with LOCS II to 0.7 for nuclear opalescence, 0.7 for nuclear color, 0.5 for cortical cataract, and 1.0 for posterior subcapsular cataract with the LOCS III, with excellent interobserver agreement. The LOCS III is an improved LOCS system for grading slit-lamp and retroillumination images of age-related cataract.
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        Split-spectrum amplitude-decorrelation angiography with optical coherence tomography

        Amplitude decorrelation measurement is sensitive to transverse flow and immune to phase noise in comparison to Doppler and other phase-based approaches. However, the high axial resolution of OCT makes it very sensitive to the pulsatile bulk motion noise in the axial direction. To overcome this limitation, we developed split-spectrum amplitude-decorrelation angiography (SSADA) to improve the signal-to-noise ratio (SNR) of flow detection. The full OCT spectrum was split into several narrower bands. Inter-B-scan decorrelation was computed using the spectral bands separately and then averaged. The SSADA algorithm was tested on in vivo images of the human macula and optic nerve head. It significantly improved both SNR for flow detection and connectivity of microvascular network when compared to other amplitude-decorrelation algorithms.
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          Depth-resolved imaging of capillary networks in retina and choroid using ultrahigh sensitive optical microangiography.

          We demonstrate the depth-resolved and detailed ocular perfusion maps within retina and choroid can be obtained from an ultrahigh sensitive optical microangiography (OMAG). As opposed to the conventional OMAG, we apply the OMAG algorithm along the slow scanning axis to achieve the ultrahigh sensitive imaging to the slow flows within capillaries. We use an 840 nm system operating at an imaging rate of 400 frames/s that requires 3 s to complete one 3D scan of approximately 3 x 3 mm(2) area on retina. We show the superior imaging performance of OMAG to provide functional images of capillary level microcirculation at different land-marked depths within retina and choroid that correlate well with the standard retinal pathology.

            Author and article information

            The Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, United States
            Author notes
            Correspondence: Amani A. Fawzi, Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, 645 N. Michigan Avenue, Suite 440, Chicago, IL 60611, USA; afawzimd@ .
            Invest Ophthalmol Vis Sci
            Invest. Ophthalmol. Vis. Sci
            Invest Ophthalmol Vis Sci
            Investigative Ophthalmology & Visual Science
            The Association for Research in Vision and Ophthalmology
            August 2018
            : 59
            : 10
            : 3858-3867
            6071478 10.1167/iovs.18-24710 iovs-59-08-56 IOVS-18-24710R1
            Copyright 2018 The Authors

            This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.



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