Purpose To detect macular perfusion defects in glaucoma using projection-resolved optical coherence tomography (OCT) angiography. Design Prospective observation study. Participants 30 perimetric glaucoma and 30 age-matched normal participants were included. Methods One eye of each participant was imaged using 6mm×6mm macular OCT angiography (OCTA) scan pattern by 70-kHz 840-nm spectral-domain OCT. Flow signal was calculated by the split-spectrum amplitude-decorrelation angiography algorithm (SSADA). A projection-resolved OCTA (PR-OCTA) algorithm was used to remove flow projection artifacts. Four en face OCTA slabs were analyzed: the superficial vascular complex (SVC), intermediate capillary plexus (ICP), deep capillary plexus (DCP) and all-plexus retina (SVC+ICP+DCP). The vessel density (VD), defined as the percentage area occupied by flow pixels, was calculated from en face OCTA. A novel algorithm was used to adjust the vessel density to compensate for local variations in OCT signal strength. Main Outcome Measures Macular retinal VD, ganglion cell complex (GCC) thickness, and visual field (VF) sensitivity. Results Focal capillary dropout could be visualized in the SVC, but not the ICP and DVP, in glaucomatous eyes. In the glaucoma group, the SVC and all-plexus retinal VD (mean±SD: 47.2%±7.1% and 73.5%±6.6%) were lower than the normal group (60.5%±4.0% and 83.2%±4.2%, both P <0.001, t test). The ICP and DCP VD were not significantly lower in the glaucoma group. Among the overall macular VD parameters, the SVC VD had the best diagnostic accuracy as measured by the area under the receiver operating characteristic curve (AROC). The accuracy was even better when the worse hemisphere (inferior or superior) was used, achieving an AROC of 0.983 and a sensitivity of 96.7% at a specificity of 95%. Among the glaucoma participants, the hemispheric SVC VD values were highly correlated with the corresponding GCC thickness and VF sensitivity (P<0.003). The reflectance compensation step in VD calculation significantly improved repeatability, normal population variation, and correlation with VF and GCC thickness. Conclusions Based on PR-OCTA, glaucoma preferentially affects perfusion in the SVC in the macula more than the deeper plexuses. Reflectance-compensated SVC VD measurement by PR-OCTA detected glaucoma with high accuracy and could be useful in the clinical evaluation of glaucoma.
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PurposeTo examine demographic and clinical factors associated with glaucomatous peripapillary retinoschisis (PPRS) and assess its association with glaucoma progression.MethodsUsing a case control study design and longitudinal data from a cohort of 166 subjects with a diagnosis of glaucoma or glaucoma suspect, we compared functional, structural, clinical, and demographic characteristics between PPRS cases and controls.ResultsThe frequency of PPRS was 6.0% (12 eyes from 10/166 subjects) with two eyes having PPRS in different sectors for a total of 15 retinoschisis events. There were no significant differences (P > 0.05) in age, sex, visual acuity, central corneal thickness, intraocular pressure, or presence of vitreous adhesion between PPRS and controls. However, eyes with PPRS tended to have a higher cup-to-disc ratio (P = 0.06), thinner RNFL (P = 0.02), and worse visual field mean deviation (MD, P = 0.06) than controls. The rate of RNFL thinning was faster in PPRS (average: −2.8%/year; range: −7.4% to 0.0%/year) than controls (−1.3%/year; range: −4.4% to 0.6%/year; P = 0.021). The rate of visual field MD change was faster in PPRS (−0.49 dB/year; range: −2.0 to 0.9 dB/year) than controls (−0.06 dB/year; range: −0.8 to 0.3 dB/year; P = 0.030). OCT scans showed hyperreflective structures spanning the PPRS whose morphology and spacing (50 ± 7 μm) are consistent with Müller glia, causing signal attenuation casting “shadows” onto distal retina.ConclusionsThis is the first report showing that glaucomatous PPRS is associated with a faster overall rate of RNFL thinning and visual field deterioration and to specifically identify OCT signs of Müller cell involvement.
BSTRACT â€" Black (Coragyps atratus) and Turkey (Cathartes aura) vultures feed heavily on carrion from domestic animals in agricultural landscapes. A recent study indicates vultures at a forested site in South Carolina had much larger home ranges than those residing in agricultural landscapes. Vulture home ranges at the forested site contained few residential or agricultural lands, and we hypothesized that vultures at that site fed extensively on wild carrion. We collected 65 regurgitated pellets from a communal night roost between 16 October 2000 and 9 April 2002 to test this hypothesis. The pellets contained undigested parts of consumed carrion including hair, bone, scales, and claws. Wild mammals, particularly white-tailed deer (Odocoileus virginianus), common raccoons {Procyon lotor), Virginia opossums {Didelphis virginiana), and striped skunks {Mephitis mephitis), were common food items. The only domestic animal recovered (in two pellets) was the house cat (Felis catus). This study supports the observations that carrion resources affect distributions and movement patterns of Black and Turkey vultures.
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