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Purpose: Further insight into the flow characteristics of the vascular features associated with diabetic retinopathy (DR) may improve assessment and treatment of disease progression. The variable interscan time analysis (VISTA) algorithm is an extension of OCT angiography (OCTA) that detects relative blood flow speeds, which then can be depicted on a color-coded map. This study used VISTA to analyze relative blood flow speeds in the microvascular changes associated with DR., Design: Cross-sectional study., Participants: Thirteen patients with varying severities of DR treated at New England Eye Center, Boston, Massachusetts., Methods: OCT angiography images centered at the fovea were obtained on a prototype swept-source OCT device, and the VISTA algorithm was applied to visualize relative blood flow speeds., Main Outcome Measures: Descriptive flow analysis of the retinal vascular features of DR was conducted on the VISTA-generated images., Results: Twenty-six eyes were included in this study. Of these, 3 eyes had mild nonproliferative DR (NPDR), 6 eyes had moderate NPDR, 4 eyes had severe NPDR, 9 eyes had proliferative DR, and 4 eyes were normal controls. Microaneurysms, intraretinal microvascular abnormalities (IRMAs), and neovascularization appeared to originate from areas of relatively slow blood flow speeds. Microaneurysms showed relatively slower flow, IRMAs showed turbulent, intermediate to slow flow, and venous beading and looping presented with relatively high flow speeds that tapered progressively. Neovascularization of venous origin demonstrated slower flow speeds, whereas that of arterial origin showed relatively high flow speeds. Additionally, increased disease severity was associated with globally slower flow speeds, with particularly slower flow around the foveal avascular zone., Conclusions: The VISTA algorithm seems to be a useful extension of OCTA that overcomes some of the limitations of normal gray-scale OCTA. It seems to have some potential in providing relevant insight into the pathogenesis of the microvascular changes associated with DR. These findings may assist in improving our understanding of the pathogenic changes that take place in DR., (Copyright © 2020. Published by Elsevier Inc.)

Purpose: With the increasing prevalence of diabetes, fast, noninvasive identification of proliferative diabetic retinopathy (PDR) becomes essential. This study evaluated the utility of optical coherence tomography angiography (OCTA) to characterize intraretinal microvascular abnormalities (IRMA) and retinal neovascularization (NV)., Methods: Patients with severe non-PDR or PDR were imaged with fluorescein angiography and widefield swept-source OCTA (Zeiss Plex Elite 9000; Carl Zeiss Meditec, Dublin, CA). Regions suspicious for IRMA or retinal NV were identified and the OCTA, including flow overlay on the co-registered structural optical coherence tomography, and fluorescein angiography images were graded by two masked readers., Results: Ninety-six foci of irregular vasculature were analyzed, comprised of 70 IRMA and 26 retinal NV lesions from 14 eyes. Compared with fluorescein angiography, OCTA with flow overlay demonstrated specificity of 99% and sensitivity of 92% in identifying IRMA and NV. Neovascularization differed from IRMA on OCTA by demonstrating supraretinal flow breaching the internal limiting membrane and posterior hyaloid (P < 0.001). Intraretinal microvascular abnormalities were distinguished from NV by outpouching of the internal limiting membrane (P = 0.035). Vascular flow was reduced in the presence of fibrosis., Conclusion: Optical coherence tomography angiography, through flow overlay, has utility to image and differentiate IRMA and NV, which are key features distinguishing severe non-PDR and PDR, respectively. Noninvasive widefield OCTA may be a useful tool to diagnose high-risk diabetic retinopathy eyes.

The present study examines the effects of heavy metals on chick embryogenesis. The metals included were cadmium, arsenic, cobalt, copper, indium, iron, manganese, and molybdenum. Salts of each of the metals were dissolved in saline and injected into the air sacs on d 2 of incubation. Dose levels varied with the metal to be tested. Control eggs were injected with an equivalent volume of saline (0.1 ml/egg). On d 14, the live embryos were removed from the eggs and examined for gross malformations. From the LD50 values, the toxicity relationship between the metals is cadmium greater than arsenic greater than cobalt greater than copper greater than indium greater than molybdenum greater than manganese greater than iron. The LD50 values were 3, 9, 38, 58, 121, 333, 765, and 1185 micrograms/egg, respectively. The gross malformations observed were reduced body size, micromelia, twisted neck, hemorrhage, everted viscera, and microphthalmia. Arsenic and cobalt were observed to be more teratogenic than other metals. This study showed that the metals tested were both toxic and teratogenic to varying degrees in chick embryogenesis.