Optic Head Research Articles

Co-assessment of OCT-A and choroidal vascularity index data in multiple sclerosis patients

To evaluate optical coherence tomography-angiography (OCT-A) findings and choroidal vascular index (CVI) in patients with multiple sclerosis (MS). 113 patients, including multiple sclerosis patients with optic neuritis attack (MSON+) and no optic neuritis attack (MSON-) and healthy control group (HCG), participated in this cross-sectional study. OCT-A images of all patients were taken and CVI was calculated. Superior flow (SF), deep flow (DF), foveal, and parafoveal superior vascular density (sVD) were decreased in the MSON+ group compared to HCG (p<0.05). Optic disc flow (ODF) and optic disc head density (ONHD) values decreased in the MS group (p<0.05). CVI was decreased in the MSON+ group compared to HCG (p<0.05). There is a correlation between CVI and foveal and parafoveal sVD. Non-invasive diagnostic tools such as OCT-A and CVI can be used for early diagnosis and follow-up of microvascular pathologies in inflammatory diseases such as MS.

Low Blind Zone Atmospheric Lidar Based on Fiber Bundle Receiving

Atmospheric constituents feature a large vertical gradient in concentration, especially at the first few hundred meters over the earth’s surface. Atmospheric lidar usually cannot cover this range due to the incomplete overlap effect or the limited dynamic range of detectors. This drawback is well known as the blind zone effect, which hinders the application of atmospheric lidars in many aspects. In this work, a method based on an optical fiber bundle was proposed to mitigate the blind zone effect. An optical fiber head with several stages, installed at the focal plane of the telescope, is used to receive backscatter light from different range levels. The design of the optical fiber head is analyzed with the ray-tracing technique. The optical fiber installed at the highest stage of the fiber head can collect far-range light like a small aperture, and all the other optical fibers are bundled into a near-range detection channel to receive backscatter light from the first few hundred meters. This special design can avoid the near-range light loss in conventional lidar systems, usually equipped with a small aperture. Different optical attenuations are then applied to near-range and far-range channels to suppress the overall signal dynamic range. This light-receiving method was applied in a 1030 nm elastic lidar, in which a fiber bundle with a three-stage fiber head was fabricated and installed. A test experiment was performed to verify this approach. A good agreement between simulations and in-system results was found. Based on this design, the blind zone of the lidar system is less than 50 m, and the detectable range can be over 10 km along the lidar’s line of sight with a single telescope receiver. This approach brings a new way of designing atmospheric lidar with a low blind zone and can strengthen our ability to monitor urban pollution and promote land-atmosphere interaction research.

Enhanced Wearable Force-Feedback Mechanism for Free-Range Haptic Experience Extended by Pass-Through Mixed Reality

We present an extended prototype of a wearable force-feedback mechanism coupled with a Meta Quest 2 head-mounted display to enhance immersion in virtual environments. Our study focuses on the development of devices and virtual experiences that place significant emphasis on personal sensing capabilities, such as precise inside-out optical hand, head, and controller tracking, as well as lifelike haptic feedback utilizing servos and vibration rumble motors, among others. The new prototype addresses various limitations and deficiencies identified in previous stages of development, resulting in significant user performance improvements. Key enhancements include weight reduction, wireless connectivity, optimized power delivery, refined haptic feedback intensity, improved stylus alignment, and smooth transitions between stylus use and hand-tracking. Furthermore, the integration of a mixed reality pass-through feature enables users to experience a comprehensive and immersive environment that blends physical and virtual worlds. These advancements pave the way for future exploration of mixed reality applications, opening up new possibilities for immersive and interactive experiences that combine useful aspects of real and virtual environments.

Online Grain Size Measurement by Laser Ultrasonics in a Hot Rolling Mill

Laser ultrasonics (LUS) has shown through numerous studies and in-situ laboratory experiments, its suitability to track microstructural features evolution as well as metallurgical transformation in steels during thermal cycles with temperatures reaching 1250°C. This prior work has motivated the use of this technology to be in applied in an industrial hot strip mill (HSM) in Eisenhüttenstadt, Germany. For this purpose, a transportable trolley which embedded LUS components (Generation and Detection Lasers, Two-Wave Mixing Interferometer, Dedicated Fibered Optical Head) was designed. The industrial investigation was carried on moving strips during normal production at several locations of the HSM, resulting in signals for high-strength lowalloy (HSLA) and advanced high-strength steel (AHSS) grades. The development of a specific data processing tool allowed calculating the grain size from the analysis of the online recorded signals. Such results were then compared to predictions from metallurgical models, finding reasonably close values. LUS appears as a suitable solution to monitor microstructural features and metallurgical transformations occurring in steel in a Hot Strip Mill (HSM) line. This approach could enable in the future the development of more reliable models and control loop of the process. This action was supported by the European commission and led by a consortium composed by ArcelorMittal, Imagine Optic and IMI-NRC.

Impact of obesity on peripapillary choroidal thickness, macular choroidal thickness, and lamina cribrosa morphology

Obesity is known to be a significant risk factor for many ocular diseases. In order to understand the mechanism of obesity-related ocular diseases, we examined the lamina cribrosa morphology, peripapillary choroidal thickness (PPCT), and macular choroidal thickness (MCT) in obese women using optical coherence tomography (OCT). This comparative cross-sectional study included the right eyes of 72 obese women and 63 healthy women classified based on body mass index (BMI). Each participant underwent a thorough ophthalmological examination and enhanced depth (EDI) OCT imaging, including measurements of PPCT from a total of 12 regions, MCT from a total of 7 regions, Bruch's membrane opening (BMO), lamina cribrosa thickness (LCT), lamina cribrosa depth (LCD), intraocular pressure (IOP), and central corneal thickness (CCT). The mean age and BMI of the obese group were 32.36±7.38 years and 35.11±4.39kg/m², while those of the control group were 31.64±7.78 years and 20.88±1.72kg/m² (p=0.658, and p<0.001, respectively). PPCT N1000, PPCT N1500, PPCT S1500, and PPCT T1500 were statistically significantly thinner in the obese group than the control group (p values were 0.039, 0.012, 0.027, and 0.036, respectively). IOP and CCT were significantly higher in the obese group than the control group (p=0.016, and p=0.019, respectively). There was no statistically significant difference between the two groups in terms of MCT, BMO, LCT, and LCD. We discovered thinning in the PPCT, which indicates microvascular abnormalities in the optic disc head. Microvascular alteration in the peripapillary region may be a potential initial event in the pathogenesis of several obesity-related ocular diseases, especially glaucoma.

Study of the influence of optical measurement of slope geometry in the working chamber for AISI 316L

The paper aims to research optical measurements of geometric slope deviations and their differences on two types of experimental specimens. The two types of specimens have plane segments inclined in the angular range of 0°- 45° and 0°- 90°, graded after 10° and 15°. Specimens were produced as six different combinations of printing parameters of a Renishaw AM500E 3D printer. At the same time, the 3D models of specimens obtained by scanning serve as a standard for inspection. A coordinate measuring machine Wenzel LH 65 with a Shapetracer 2 optical head and an Atos Gom MV 300 scanner were used for evaluation. Based on the research, best 3D printing parameters were decided, position in the printing space of the printer and the effects of deformation triggered by supports at different inclinations of the plane segments. The analysis of experiments supplied the best geometric deviations of the slope for specimens.

Seeker head geometric parameters influence on the hypersonic aero-optical effect.

The aero-optical effect of hypersonic flight vehicles creates serious distortion on the imaging system. In this paper, based on the 2D model of a typical optical seeker, flow field density data are obtained by numerical simulation with different optical seeker head radii, cone angles, and relative positions of incident rays reaching the window as variables. Through a series of evaluation parameters, the aero-optical effect under different conditions is quantitatively computed by a ray tracing method. The results show that with the increase of the line of sight (LOS) angle, image deviation decreases. When the optical seeker radius is 40mm and the cone angle is more than 20°, image deviation will not change with the increase of the cone angle. In the case of a small cone angle, the bore sight error (BSE) decreases gradually with the increase of LOS angle. The BSE decreases with the increase of the cone angle, and tends to be stable when the cone angle is above 40°. The variation of the optical path difference with respect to the flow field density is more sensitive than the distance from the shock wave region to the optical seeker window. The Strehl ratio decreases with the increase of the optical seeker cone angle, indicating that the larger the cone angle, the worse the imaging quality.

Clinical Relevance of Choroidal Thickness in Obese and Healthy Children: A Machine Learning Study.

To analyze the effect of macular choroidal thickness (MCT) and peripapillary choroidal thickness (PPCT) on the classification of obese and healthy children by comparing the performance of the random forest (RF), support vector machine (SVM), and multilayer perceptrons (MLP) algorithms. Fifty-nine obese children and 35 healthy children aged 6 to 15 years were studied in this prospective comparative study using optical coherence tomography. MCT and PPCT were measured at distances of 500 μm, 1,000 μm, and 1,500 μm from the fovea and optic disc. Three different feature selection algorithms were used to determine the most prominent features of all extracted features. The classification efficiency of the extracted features was analyzed using the RF, SVM, and MLP algorithms, demonstrating their efficacy for distinguishing obese from healthy children. The precision and reliability of measurements were assessed using kappa analysis. The correlation feature selection algorithm produced the most successful classification results among the different feature selection methods. The most prominent features for distinguishing the obese and healthy groups from each other were PPCT temporal 500 μm, PPCT temporal 1,500 μm, PPCT nasal 1,500 μm, PPCT inferior 1,500 μm, and subfoveal MCT. The classification rates for the RF, SVM, and MLP algorithms were 98.6%, 96.8%, and 89%, respectively. Obesity has an effect on the choroidal thicknesses of children, particularly in the subfoveal region and the outer semi-circle at 1,500 μm from the optic disc head. Both the RF and SVM algorithms are effective and accurate at classifying obese and healthy children.

Quantifying MR head motion in the Rhineland Study – A robust method for population cohorts

Head motion during MR acquisition reduces image quality and has been shown to bias neuromorphometric analysis. The quantification of head motion, therefore, has both neuroscientific as well as clinical applications, for example, to control for motion in statistical analyses of brain morphology, or as a variable of interest in neurological studies. The accuracy of markerless optical head tracking, however, is largely unexplored. Furthermore, no quantitative analysis of head motion in a general, mostly healthy population cohort exists thus far. In this work, we present a robust registration method for the alignment of depth camera data that sensitively estimates even small head movements of compliant participants. Our method outperforms the vendor-supplied method in three validation experiments: 1.similarity to fMRI motion traces as a low-frequency reference, 2.recovery of the independently acquired breathing signal as a high-frequency reference, and 3.correlation with image-based quality metrics in structural T1-weighted MRI. In addition to the core algorithm, we establish an analysis pipeline that computes average motion scores per time interval or per sequence for inclusion in downstream analyses. We apply the pipeline in the Rhineland Study, a large population cohort study, where we replicate age and body mass index (BMI) as motion correlates and show that head motion significantly increases over the duration of the scan session. We observe weak, yet significant interactions between this within-session increase and age, BMI, and sex. High correlations between fMRI and camera-based motion scores of proceeding sequences further suggest that fMRI motion estimates can be used as a surrogate score in the absence of better measures to control for motion in statistical analyses.

MHV-68 induces central nervous system autoimmunity in an MBP-specific TCR transgenic mouse model of multiple sclerosis

Abstract Multiple Sclerosis (MS) is a demyelinating autoimmune disease of the central nervous system. Latent infection with Epstein-Barr virus (EBV) has been identified as a necessary yet insufficient factor in the development of the disease. Several groups have demonstrated that the murine EBV analogue, MHV-68, exacerbates disease severity in experimental autoimmune encephalomyelitis (EAE). However, the induction of EAE requires immunization and does not fully replicate the clinical features of MS. We sought to develop a virus-inducible model that accurately represents MS etiology and does not rely on classical EAE immunization. Using a transgenic mouse line with a myelin basic protein-specific T cell receptor, we found that MHV-68 induces demyelinating disease in 72% of infected mice. These mice exhibit clinical features such as optic neuritis, incontinence, and head tilt, which are commonly observed in MS patients but not in mice with EAE. This phenomenon was specific to MHV-68 and was not seen with other viral pathogens including PR8 influenza. Our work demonstrates that latent gammaherpesvirus infection can drive CNS autoimmunity in genetically predisposed mice without prior EAE induction, thus providing a more natural murine model of MS. National Institute of Health R01AI140741-04

Comparison of optic disc head vascular density status between crowded and normal discs: An optical coherence tomography angiography study.

To compare the optic disc capillary vascular status between crowded and normal optic discs using optical coherence tomography angiography (OCT-A). A total of 101 eyes were included in this cross-sectional, comparative study. Fifty-one eyes with crowded optic discs (Group 1) were compared with 50 eyes with normal discs (Group 2). Peripapillary and optic disc head capillary vascular density measurements were obtained quantitatively with OCT-A. Mean ages were 46.2±6.2 years in Group1 and 45.9±6.0 years in Group2 (p=0.796).Vertical disc diameters were 1.52±0.2mm in Group 1 and 1.61±0.16mm in Group 2 (p=0.022) whereas horizontal disc diameters were 1.53±0.17mm in Group 1 and 1.61±0.13mm in Group 2(p˂0.014). OCT-A findings were as follows: radial peripapillary capillary, vascular density whole image measurements (%); 49.6±2.3 in Group 1 and 49.1±2.3 in Group 2 (p=0.292), peripapillary capillary density; 53.3±2.8 in Group 1 and 52.6±2.6 in Group 2 (p=0.176), inside disc measurements 52.4 (48.7-54.7) in Group 1 and 46.5 (42.6-49.6) in Group 2 (p˂0.001). RNFL was 118.2±12.2µm in Group 1 and 110.8±11.4µm in Group 2(p=0.002). The vascular density of the disc circumference in individuals with healthy crowded optic discs is not different from those with normal discs. However, inside disc measurements differ between crowded and normal size discs. This finding suggests that when the disc size is reduced, the amount of vessels in it does not decrease in a way that correlates with the size. Therefore, the vascular structures are suitable for compression in the narrow optic nerve head.

Recent overviews on the drug delivery aspects and applications of brinzolamide for the management of glaucoma

Brinzolamide (BRZ) is a highly selective carbonic anhydrase (CA) inhibitor which leads to decreases intraocular pressure (IOP) by slowing down the production of aqueous humour. It is indicated for the topical care of primary open-angle glaucoma (POAG) with ocular hypertension (OH), as 1% ocular suspension (Azopt) is applied twice or three times. A complex optic neuropathy known as POAG is characterized by the gradual loss of ganglion cells, including their axon. The main risk factor is elevated IOP, the only curable risk factor that can harm the optic head (ONH). To improve the absorption and bioavailability of BRZ in such eye-related complications, various drug delivery vehicles and nano-carriers such as Liposomes, In-situ Gelling systems, Nanofiber, TPGS-based nanoliposomes, Nanocapsules, Nanoemulsion, Niosomes and Nano lipid carrier are briefly suggested in the literature. Different strategies based on nano-carriers have shown to be successful for site-targeted delivery and demonstrate the basic structure with the altered pharmacodynamics property of BRZ. This review summarizes recent advancements in the management of glaucoma and the use of nano-carriers for molecular therapeutics of Glaucoma since it has distinct cellular targets, particularly the trabecular meshwork of the anterior portion of the eye.

Compact laser spectroscopic sensor head prototype for time-resolved breath oxygen monitoring

A small and lightweight optical sensor head prototype with a disposable airway adapter for continuous mainstream monitoring of oxygen at high sampling rate is designed and tested on an optical benchtop. In terms of its size and functionality, the sensor head design is similar to current capnography systems from leading medical equipment manufacturers, and it has been designed within constraints of potential applications in direct breath oxygen monitoring that require direct interaction with the gas inside a breathing tube. The measurement precision of 0.1% O2 with a 10 ms integration time are well within the performance required for breath O2 monitoring applications.

Macular and Optic Disc Head Morphology on OCT and Visual Prognosis in Non-Arteritic Anterior Ischemic Optic Neuropathy

Introduction: Non-arteritic anterior ischemic optic neuropathy (NAION) shows an acute painless unilateral visual loss due to a reduced perfusion of the optic nerve head (ONH). Aim of this study was to analyse ONH respective macula morphology after NAION by optical coherence tomography and the correlation to visual acuity.

Deep Learning Application to Detect Glaucoma with a Mixed Training Approach: Public Database and Expert-Labeled Glaucoma Population

Introduction: Artificial intelligence has real potential for early identification of ocular diseases such as glaucoma. An important challenge is the requirement for large databases properly selected, which are not easily obtained. We used a relatively original strategy: a glaucoma recognition algorithm trained with fundus images from public databases and then tested and retrained with a carefully selected patient database. Methods: The study’s supervised deep learning method was an adapted version of the ResNet-50 architecture previously trained from 10,658 optic head images (glaucomatous or non-glaucomatous) from seven public databases. A total of 1,158 new images labeled by experts from 616 patients were added. The images were categorized after clinical examination including visual fields in 304 (26%) control images or those with ocular hypertension and 347 (30%) images with early, 290 (25%) with moderate, and 217 (19%) with advanced glaucoma. The initial algorithm was tested using 30% of the selected glaucoma database and then re-trained with 70% of this database and tested again. Results: The results in the initial sample showed an area under the curve (AUC) of 76% for all images, and 66% for early, 82% for moderate, and 84% for advanced glaucoma. After retraining the algorithm, the respective AUC results were 82%, 72%, 89%, and 91%. Conclusion: Using combined data from public databases and data selected and labeled by experts facilitated improvement of the system’s precision and identified interesting possibilities for obtaining tools for automatic screening of glaucomatous eyes more affordably.

Reduction of motion axis by sensitivity calibration of sensor in shape measurement instrument using normal vector tracing.

High-precision free-form surface mirrors are required for synchrotron radiation facilities in the scientific field and semiconductor lithography systems in the industrial field. Previously, we developed a nano-profiler with the goal of achieving a measurement accuracy of 30nm. The nano-profiler scanned and measured the slope angle of the surface to be measured with laser light and calculated the shape from the angle information. By driving the optical head and surface to be measured with four rotation axes and one translation axis, the surface could be scanned while keeping the optical path length constant. Although the rotation axis was controlled by a high-precision rotary encoder, pitching and yawing errors occurred in the translation axis. In this study, we attempt to eliminate the error of pitching and yawing from the conventional measurement operation of four axes of rotation and one axis of translation to the drive of only four axes of rotation. If the translation drive is eliminated, the optical path length will not be constant, and the sensitivity of the light-receiving element will change. Therefore, we propose a new method to calibrate the sensitivity of the receiving element and perform a comparative measurement with the conventional measurement method. Comparing the measured shapes obtained by both measurement results, it was found that the shapes had a maximum peak to valley difference of 6.2nm. Thus, the proposed novel measurement method allows a significant reduction in pitching and yawing errors.

Rho-kinase Inhibitor: A Potential Alternative to Current Glaucoma Therapy

Glaucoma is a group of progressive and irreversible optic neuropathies linked to intraocular pressure-related damage of the optic head. It is the second leading cause of blindness with estimation of 76 million people affected. Among many types of glaucoma, Primary Open-Angle Glaucoma (POAG) is the most common. Management of POAG primarily focus on lowering IOP with a variety of topical, oral, intravenous therapy, and surgery. Prostaglandin Analogue and Beta-blocker have long been the first line therapy for POAG with proven efficacy and safety profile. Rho-kinase Inhibitor is a novel class of drug with IOP lowering property through its ability to increase aqueous humor drainage via trabecular meshwork. Rho-kinase Inhibitor is proven to have mild local adverse effects and rare systemic drug reaction. This might be beneficial for patients with contraindication to Prostaglandin Analogue and/ or Beta-blocker use. Keywords: glaucoma, rho-kinase inhibitor

Two-Fold Color Compensation Algorithm Operation for Optical See-Through Head Mounted Display

Two-Fold Color Compensation Algorithm Operation for Optical See-Through Head Mounted Display

Enhanced-spatial-resolution optical surface profiler based on focusing deflectometry.

Deflectometric slope profiler is an essential technique for accessing the surface metrology of mirrors used in synchrotron radiation beamlines. To increase the upper spatial frequency bandwidth limits of deflectometric slope profiler, reducing the beam spot size on the mirrors is necessary. In this paper, we introduce a profiler system: the focusing long trace profiler (FLTP). It contains a newly developed optical head capable of raising upper spatial frequency bandwidth limits by using a focused beam instead of a collimated beam to scan the sample. This feature has been proven in a numerical simulation experiment, where a spatial resolution of up to around 0.05 mm was reached when the sample is set at focus plane. The system is implemented and characterized in several experiments; calibration of the focusing optical head shows that it can achieve a high angular accuracy of sub-50 nrad root-mean-square (rms) and defocusing of sample under test (SUT) has no effect on the measurement results; the measurement tests also demonstrate the system's advantage in highly curved mirror profile metrology.

Temperature-Monitored Fibre Optic Current Sensor Using Channelled-Spectrum Analysis

The fibre optic current sensor demonstrated here uses the intrinsic temperature and wavelength dependence of the Verdet constant of a terbium gallium garnet (TGG) magneto-optic material and the two micro-optic linear polarizers attached, to simultaneously extract the values of temperature and the optical Faraday rotation (induced by the presence of the magnetic field due an electric current on a conductor) without any extra optical component attached to the optical sensor head. The simultaneous measurement is achieved by illuminating the sensor head with a broadband optical source and by careful signal processing of the originated channelled-spectrum, compensate the sensor’s temperature dependence.