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Significance: Mueller matrix imaging (MMI) is a comprehensive form of polarization imaging useful for assessing structural changes. However, there is limited literature on the polarimetric properties of brain specimens, especially with multispectral analysis., Aim: We aim to employ multispectral MMI for an exhaustive polarimetric analysis of brain structures, providing a reference dataset for future studies and enhancing the understanding of brain anatomy for clinicians and researchers., Approach: A multispectral wide-field MMI system was used to measure six fresh lamb brain specimens. Multiple decomposition methods (forward polar, symmetric, and differential) and polarization invariants (indices of polarimetric purity and anisotropy coefficients) have been calculated to obtain a complete polarimetric description of the samples. A total of 16 labels based on major brain structures, including grey matter (GM) and white matter (WM), were identified. K -nearest neighbors classification was used to distinguish between GM and WM and validate the feasibility of MMI for WM identification., Results: As the wavelength increases, both depolarization and retardance increase, suggesting enhanced tissue penetration into deeper layers. Moreover, utilizing multiple wavelengths allowed us to track dynamic shifts in the optical axis of retardance within the brain tissue, providing insights into morphological changes in WM beneath the cortical surface. The use of multispectral data for classification outperformed all results obtained with single-wavelength data and provided over 95% accuracy for the test dataset., Conclusions: The consistency of these observations highlights the potential of multispectral wide-field MMI as a non-invasive and effective technique for investigating the brain's architecture., (© 2024 The Authors.)

The Stingray sensor system is a 15-camera optical array dedicated to the nightly astrometric and photometric survey of the geosynchronous Earth orbit (GEO) belt visible above Tucson, Arizona. The primary scientific goal is to characterize GEO and near-GEO satellites based on their observable properties. This system is completely autonomous in both data acquisition and processing, with human oversight reserved for data quality assurance and system maintenance. The 15 ZWO ASI1600MM Pro cameras are mated to Sigma 135 mm f/1.8 lenses and are controlled simultaneously by four separate computers. Each camera is fixed in position and observes a 7.6-by-5.8-degree portion of the GEO belt, for a total of a 114-by-5.8-degree field of regard. The GAIA DR2 star catalog is used for image astrometric plate solution and photometric calibration to GAIA G magnitudes. There are approximately 200 near-GEO satellites on any given night that fall within the Stingray field of regard, and all those with a GAIA G magnitude brighter than approximately 15.5 are measured by the automated data reduction pipeline. Results from an initial one-month survey show an aggregate photometric uncertainty of 0.062 ± 0.008 magnitudes and astrometric accuracy consistent with theoretical sub-pixel centroid limits. Provided in this work is a discussion of the design and function of the system, along with verification of the initial survey results.

Purpose: To evaluate the prevalence and types of artifacts in ultrawide-field swept-source optical coherence tomography angiography (SS-OCTA) scans of diabetic retinopathy (DR) patients., Methods: This study was a prospective, observational study conducted from May 2022 to October 2022. Participants comprised individuals with proliferative diabetic retinopathy (PDR), nonproliferative diabetic retinopathy (NPDR), no diabetic retinopathy, and healthy controls. SS-OCTA imaging was performed, and a 5-scan composite with a larger field of view (23.5 mm × 17.5 mm) was captured using built-in software. Two experienced ophthalmologists analyzed the images independently, and the image quality and artifact prevalence were recorded and analyzed., Results: The study included 70 eyes (16 with PDR, 24 with NPDR, 12 eyes of diabetic patients without DR, and 18 healthy eyes) in 70 subjects. Imaging artifacts were observed in a high percentage of eyes, with 98.57% of eyes presenting at least one type of artifact. A significant proportion of eyes (58.57%) exhibited a severe degree of artifacts. The most prevalent artifacts were loss of signal in 63 eyes (90%) and displacement artifact and masking artifact in 43 eyes (61.4%). Patients with more severe stages of DR had higher artifact scores ( p  < 0.05). Multivariate regression analysis indicated that DR severity was the most important factor influencing artifact scores ( p  < 0.05)., Conclusions: In OCTA photos, various artifacts arise at different frequencies. It is crucial to qualitatively evaluate the images to ensure their quality. The results demonstrate that DR severity has a significant correlation with artifact scores.

Purpose: To compare indocyanine green angiography (ICGA) and swept-source wide-field optical coherence tomography angiography (SS-OCTA) for the assessment of patients with posterior uveitis., Method: SS-OCTA montage images of 5 x 12 x 12 mm or 2 x 15 x 9 mm, covering ~70-90 degree of the retina of consecutive patients with posterior uveitis were acquired. The choriocapillaries and choroidal slabs were compared to findings on ICGA., Results: Sixty-eight eyes of 41 patients were included (mean age 47.2 ± 20.4 years; 58.5% female). In 23 (34%) lesions were visible on OCTA, but not discernable on ICGA. In turn, out of the 45 eyes with clearly discernable lesions on ICGA, 22 (49%) and 21 (47%) eyes showed no corresponding areas of flow deficit on OCTA in the CC and choroidal slab, respectively. Lesion size strongly correlated among ICGA and OCTA choriocapillaries- (CC) (r = 0.99, p ≤ 0.0001) and choroidal slabs (r = 0.99, p ≤ 0.0001), respectively. The mean lesion size on the late frames of ICGA (8.45 ± 5.47 mm 2 ) was larger compared to the lesion size on OCTA CC scan (7.98 ± 5.47 mm 2 , p ≤ 0.0001) and choroidal scan (7.69 ± 5.10 mm 2 , p = 0.002), respectively. The lesion size on OCTA CC scan was significantly larger than on the OCTA choroidal scan ( p ≤ 0.0001)., Conclusion: SS-wide field OCTA may be a promising tool to assess posterior uveitis patients and may replace ICGA to a certain extent in the future., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Tian, Zeng, Tappeiner, Zinkernagel, Wolf and Munk.)

Purpose: To report five cases of ocular Toxocariasis (OT) in which ultrawide-field (UWF) imaging was helpful in diagnosis and assessment. OT is an underdiagnosed condition triggered by the ocular invasion of Toxocara larvae. Typical features are peripheral granuloma or endophthalmitis., Methods: A retrospective case series of 10 outpatients were studied by complete ophthalmologic examination and complementary tests. UWF retinal imaging, fundus autofluorescence (FAF) and spectral-domain optical coherence tomography (SDOCT) were retrospectively analyzed. Five patients with suspected OT were included., Results: UWF imaging and FAF was able to detect all retinal lesions in a single rapid capture. Two patients showed positive serology for Toxocara. An image suggesting the larva in the vitreous cavity was shown in one patient. Antihelmintic 15 treatment along with steroids was prescribed in two patients., Conclusion: UWF imaging and SDOCT provide a more efficient approach and follow-up in OT, raising final standards of care.

Purpose: We investigated the wide-field choroidal thickness (CT) using swept-source optical coherence tomography (SS-OCT) and compared the characteristics of the choroidal layer between pachychoroid and normochoroid groups., Methods: A total of 120 eyes from 120 normal subjects were included. All subjects were divided into two groups according to the subfoveal CT (≥300 μm, pachychoroid group; <300μm, normochoroid group). All subjects underwent an HD spotlight 16 mm scan using SS-OCT. The CT was measured at the following 12 points: subfoveal, 3 points in the nasal peripapillary area, 6 points in the macular area and 2 peripheral points at 5400 and 8100 µm from the fovea. The CT measurements were compared between the two groups, and statistical analyses were performed to determine clinical factors associated with each point of the CT., Results: The CT in the pachychoroid group was thicker than that in the normochoroid group at all points (p < 0.01). The CTs of the two groups in the macular area were highly associated with the subfoveal CT. However, the CTs of the nasal peripapillary and peripheral areas showed lower associations with the subfoveal CT and lower diagnostic abilities for the pachychoroid group. The existence of pachyvessels was found to be a significant factor causing the regional variations., Conclusions: The CTs in the peripapillary and peripheral areas showed different patterns than the subfoveal CT. Regional variations by pachyvessels were more frequent in the peripapillary and peripheral areas than in the macular area, and the subfoveal CT did not represent the whole choroidal area., (© 2020 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

A 20 m space telescope is described with an unvignetted 1° field of view-a hundred times larger in area than fields of existing space telescopes. Its diffraction-limited images are a hundred times sharper than from wide-field ground-based telescopes and extend over much if not all the field, 40 arcmin diameter at 500 nm wavelength, for example. The optical system yielding a 1°, 1.36 m diameter image at f/3.9 has relatively small central obscuration, 9% by area on axis, and is fully baffled. Several carousel-mounted instruments can each access directly the full image. The initial instrument complement includes a 400 gigapixel silicon imager with 2 µm pixels (0.005 arcsec), and a 60 gigapixel HgCdTe imager with 5 µm pixels (0.012 arcsec). A multi-object spectrograph with 10 000 fibres will allow spectroscopy with 0.02 arcsec resolution. Direct imaging and spectroscopy of exoplanets can take advantage of the un-aberrated, on-axis image (5 nm RMS wavefront error). While this telescope could be built for operation in free space, a site accessible to a human outpost at the Moon's south pole would be advantageous, for assembly and repairs. The lunar site would allow also for the installation of new instruments to keep up with evolving scientific priorities and advancing technology. Cooling to less than 100E K would be achieved with a surrounding cylindrical thermal shield. This article is part of a discussion meeting issue 'Astronomy from the Moon: the next decades'.

Purpose: To analyze imaging artifacts and segmentation errors with wide-field swept-source optical coherence tomography angiography (SS-OCTA) in diabetic retinopathy (DR)., Methods: We conducted a prospective, observational study at Massachusetts Eye and Ear from December 2018 to March 2019. Proliferative diabetic retinopathy (PDR), nonproliferative diabetic retinopathy (NPDR), diabetic patients with no diabetic retinopathy (DR), and healthy control eyes were included. All patients were imaged with a SS-OCTA and the Montage Angio (15 × 9 mm) was used for analysis. Images were independently evaluated by two graders using the motion artifact score (MAS). All statistical analyses were performed using SPSS 25.0 and R software., Results: One hundred thirty-six eyes in 98 participants with the montage image were included in the study. Patients with more severe stages of DR had higher MAS by trend test analysis ( P < 0.05). The occurrence of segmentation error was 0% in the healthy group, 10.53% in the no DR group, 10.00% in the NPDR group, and 50% in the PDR group. Multivariate regression analysis showed that the severity of DR and dry eye were the major factors affecting MAS ( P < 0.05). There were some modifiable artifacts that could be corrected to improve image quality., Conclusions: Wide field SS-OCTA assesses retinal microvascular changes by noninvasive techniques, yet distinguishing real alterations from artifacts is paramount to accurate interpretations. DR severity and dry eye correlated with MAS., Translational Relevance: Understanding contributing factors and methods to reduce artifacts is critical to routine use and clinical trial with wide-field SS-OCTA., (Copyright 2019 The Authors.)

The use of fluorescence microscopy is central to cell biology in general, and essential to many fields (e.g., membrane traffic) that rely upon it to identify cellular locations of molecules under study and the extent to which they co-localize with others. Rigorous localization or co-localization data require quantitative image analyses that can vary widely between fields and laboratories. While most published data use two-dimensional images, there is an increasing appreciation for the advantages of collecting three-dimensional data sets. These include the ability to evaluate the entire cell and avoidance of focal plane bias. This is particularly important when imaging and quantifying changes in organelles with irregular borders and which vary in appearance between cells in a population, e.g., the Golgi. We describe a method developed for quantifying changes in signal intensity of one protein within any three-dimensional structure, defined by the presence of a different marker. We use as examples of this method the quantification of adaptor recruitment to transmembrane protein cargos at the Golgi though it can be directly applied to any site in the cell. Together, these advantages facilitate rigorous statistical testing of differences between conditions, despite variations in organelle structure, and we believe that this method of quantification of fluorescence data can be productively applied to a wide array of experimental questions.