Speckle Pattern Research Articles

Impaired systemic microvascular function in patients with resistant arterial hypertension and microalbuminuria: an observational study

Abstract Background Systemic arterial hypertension (SAH) is one of the most prevalent diseases worldwide and is known to be associated with alterations of microvascular function. It is well known that microalbuminuria (MAU) is considered an early marker of renal and cardiac injury in SAH and is an independent risk factor for cardiovascular events in this population. Additionally, it is associated with altered endothelial function, which occurs from the early stages and can be considered an early marker. In some cases, SAH presents as resistant arterial hypertension (RAH), resulting in a worse prognosis compared to individuals with non-resistant hypertension. Moreover, MAU is associated with higher mortality, independent of glomerular filtration rate. Endothelial dysfunction is also a risk marker found in different conditions and can add to MAU in patients with RAH. Purpose To investigate systemic microvascular function in patients with RAH, with or without MAU. Methods 64 patients with RAH, of both genders (50% men), were evaluated, with 32 having MAU and 32 without MAU (defined as a urinary albumin/creatinine ratio between 30 and 300 mg/g in a routine urine sample). Microvascular function assessment was performed using a laser speckle system, allowing analysis of cutaneous microvascular flow. Flow measurements were expressed in arbitrary perfusion units (APU) divided by the mean arterial pressure to obtain cutaneous vascular conductance (CVC). A post-occlusive reactive hyperemia (PORH) test was performed, with brachial artery occlusion using a sphygmomanometer 50 mmHg above systolic pressure for 3 minutes; cutaneous flow was measured after release of the occlusion. Results Patients with or without MAU did not differ in terms of age, frequency of diabetes, and chronic kidney disease. The peak CVC values during PORH were 0.64 ± 0.15 and 0.55 ± 0.15 APU/mmHg in RH and RH + MAU patients, respectively (P=0.03). The delta values (peak – baseline) during PORH were 0.31 ± 0.11 and 0.25 ± 0.09 APU/mmHg in RH and RH + MAU patients, respectively (P=0.04)(Figure 1). Conclusions PORH-induced vasodilation was found to be reduced in patients with RAH and MAU compared to patients without MAU. This finding shows alteration of endothelium-dependent vasodilation mechanisms in these patients, indicating reduced systemic microvascular endothelial function. Endothelial dysfunction may be associated with glomerular permeability changes, contributing to MAU and further increasing the risk for these patients. This suggests the need for more intensive therapeutic interventions and better risk stratification for these patients, as endothelial dysfunction can be found in the early stages of the disease.Figure 1

High-speed 3D measurement using the kinoform array and light source shift

A new, to the best of our knowledge, fringe projector using the kinoform is proposed in this Letter. The kinoform array makes the hologram easy to manufacture, and the phase shift is realized by light source shift. The fringes can be shifted at a high speed due to the high-speed switch of the light source. An active binocular 3D measurement system using the proposed projector is demonstrated, and a binocular matching algorithm from coarse to fine using a laser speckle and fringe phase is proposed. Three laser diodes are adopted as light sources, and the three-step phase-shifting is achieved. The dimension of the projector is 30 mm × 26 mm × 12 mm and the switching speed is up to 1.5 kHz. The 3D measurement speed reaches 70 fps in the experiment.

Comprehensive validation of a compact laser speckle contrast imaging system for vascular function assessment: from the laboratory to the clinic.

Proper organ functioning relies on adequate blood circulation; thus, monitoring blood flow is crucial for early disease diagnosis. Laser speckle contrast imaging (LSCI) is a noninvasive technique that is widely used for measuring superficial blood flow. In this study, we developed a portable LSCI system using an 805-nm near-infrared laser and a monochrome CMOS camera with a 10 × macro zoom lens. The system achieved a high-resolution imaging (1280 × 1024 pixels) with a working distance of 10 to 35 cm. The relative flow velocities were visualized via a spatial speckle contrast analysis algorithm with a 5 × 5 sliding window. In vitro experiments demonstrated the system's ability to image flow velocities in a fluid model, and a linear relationship was observed between the actual flow rate and the relative flow rate obtained by the system. The correlation coefficient (R2) exceeded 0.83 for volumetric flow rates of 0 to 0.2 ml/min when channel widths were greater than 1.2 mm, and R2 > 0.94 was obtained for channel widths exceeding 1.6 mm. Comparisons with laser Doppler flowmetry (LDF) revealed a strong positive correlation between the LSCI and LDF results. In vivo experiments captured postocclusive reactive hyperemic responses in rat hind limbs and human palms and feet. The main research contribution is the development of this compact and portable LSCI device, as well as the validation of its reliability and convenience in various scenarios and environments. Future applications of this technology include evaluating blood flow changes during skin injuries, such as abrasions, burns, and diabetic foot ulcers, to aid medical institutions in treatment optimization and to reduce treatment duration.

H2S-Eluting Hydrogels Promote In Vitro Angiogenesis and Augment In Vivo Ischemic Wound Revascularization

Ischemic wounds are frequently encountered in clinical practice and may be related to ischemia secondary to diabetes, peripheral artery disease and other chronic conditions. Angiogenesis is critical to the resolution of ischemia. Hydrogen sulfide (H2S) is now recognized as an important factor in this process. H2S donors NaHS and GYY4137 were incorporated into the photosensitive polymer hydrogel gelatin methacrylate and evaluated. Human umbilical vein endothelial cell (HUVEC) culture was used to quantify toxicity and angiogenesis. Sprague Dawley rats were subjected to ischemic myocutaneous flap wound creation with and without application of H2S-eluting hydrogels. Tissue perfusion during wound healing was quantified using laser speckle contrast imaging, and gene and protein expression for VEGF were evaluated. Vascular density was assessed by CD31 immunohistochemistry. Successful incorporation of sulfide compounds was confirmed by scanning electron microscopy with energy-dispersive X-ray analysis, and under physiologic conditions, detectable H2S was present for up to 14 days by high-performance liquid chromatography. HUVECs exposed to hydrogels did not demonstrate excess cytotoxicity or apoptosis. A two-fold increase in angiogenic tube formation was observed in HUVECs exposed to H2S-eluting hydrogels. Rat ischemic flap wounds demonstrated greater perfusion at 14 days, and there was greater vascularity of healed wounds compared to untreated animals. A nearly two-fold increase in VEGF mRNA and a four-fold increase in VEGF protein expression were present in wounds from treated animals. Local-regional administration of H2S represents a novel potential therapeutic strategy to promote angiogenesis and improve wound healing after tissue injury or as a result of ischemic disease.

Experimental method for internal deformation measurement of 3D solids with embedded cracks based on 3D printing and digital speckle techniques

Quantification of the internal deformation of fractured solids such as rock masses under external loads, especially the deformation around internal fractures, is crucial for understanding and predicting the failure of fractured solids. However, it is very difficult to achieve the goal using conventional experimental methods. In this study, we proposed a novel internal deformation measurement method based on three-dimensional (3D) printing and digital speckle techniques. The 3D printing technology was applied to fabricate a 3D transparent model with an embedded elliptical crack and to set a speckle pattern on the internal section of the transparent model. The digital image correlation (DIC) method was used to determine the internal deformation field of the 3D fractured model. The measured displacements and strains of the internal sections in the fractured model were compared with the numerical simulation results. The comparison indicates that the proposed experimental method can well determine the deformation inside the 3D model. This built-in speckle method can realize real-time observation of the internal deformation of a 3D solid model in a non-contact and non-destructive manner.

Naturalization and evaluation of synthetic random stripes pattern for digital image correlation

Abstract The morphology of speckle patterns commonly used in the Digital Image Correlation (DIC) community can be categorized into artificially generated free shapes and computer-synthesized circular dots. Due to the non-repeatability of manually sprayed patterns, researchers tend to favour code-controlled dot patterns, which exist in two forms: “white dots on a black background” and “black dots on a white background”. However, from the perspective of biological evolution, these two dot patterns can be hybridized “in silico” using the Turing model to create an intermediate form—the “striped-like” pattern. This hybridization significantly improves species identification and environmental adaptability. Although there have been reports on producing stripe patterns based on the kernel-based Turing model, there is no specific speckle pattern generation specification or comprehensive evaluation research for DIC applications. This paper naturalizes a novel striped speckle pattern and a corresponding generation approach. The pattern quality was assessed and compared with circular dots and hand-sprayed speckles. The stripes pattern outperformed the other two forms regarding Mean Intensity Gradient (MIG), q-factor, systematic bias, and random error. Sub-pixel displacement simulation and actual translation test results demonstrate that the proposed striped pattern offers higher precision and robustness in displacement and static strain measurements. Therefore, this striped pattern provides a preferred alternative for DIC technicians.

Clinical relevance and frequency of cytoplasmic patterns observed in ANA-Hep-2: experience of Cairo University Hospitals.

Antinuclear antibodies (ANA) are the most common biomarkers observed in autoimmune diseases. Cytoplasmic staining patterns on ANA-Hep-2 are gaining recognition but with scanty information about their clinical and diagnostic role. The aim is to assess the frequency of cytoplasmic ANA patterns in autoimmune diseases, and to evaluate their possible associations with clinical diagnoses and autoantibodies. This observational cross-sectional study was conducted by examining and/or reviewing ANA by indirect immunofluorescence assay during a 13-month period. This was followed by testing the group of patients with a positive cytoplasmic staining pattern (n = 92) using the Microblot-Array ANA plus for the presence of 44 specific autoantibodies. Out of 2741 samples, 1791 (65.3%) tested negative, 845 (30.9%) tested positive nuclear staining patterns, 56 (2.0%) positive solitary cytoplasmic staining patterns, and 49 (1.8%) positive mixed nuclear and cytoplasmic patterns. Ninety-two cases (3.4% of the total cases) were analyzed using Microblot-Array ANA plus, with reticular as the most frequent cytoplasmic pattern, followed by dense fine speckled. The most frequently associated disease with reticular pattern was primary biliary cholangitis (28.9%), and the most frequently detected autoantibodies were against M2 (66.7%). The most frequently associated disease with dense fine speckled pattern was systemic lupus erythematosus (69.4%), and the most frequently detected autoantibodies were against nucleosome (57.7%) and ribosomal P0 (53.8%). This study highlights the significance of reporting cytoplasmic staining patterns and their importance in assessment of autoimmune diseases. Larger cohort studies on treatment naïve patients are recommended.

Learning‐Based Vectorial Reconstruction of Orthogonal Polarization Components in a Structured Vector Optical Field Passing Through Scattering Media

AbstractOptical imaging through scattering media has become important due to its fundamental physics interest and various applications. The reconstruction of a structured optical field with various states of polarization passing through a scattering medium with a speckle pattern behind the scattering medium remains challenging since existing restoring techniques only reconstruct the speckle in a single‐polarization state (scalar optical field). This work proposes a novel approach to simultaneously restore the initial orthogonally polarized components from a speckle pattern behind a scattering medium. The neural network Polarization‐DenseUnet (P‐DenseUnet) based on the vector transfer matrix is constructed to restore the two orthogonally linear (or circular) polarization components of a structured vector optical field from a speckle pattern behind the scattering medium. The generalization and effectiveness of this proposed method are tested for high fidelity with different phase distributions such as vortex, digits, and Fashion‐mnist.

Increased Levels of Circulating Methylglyoxal Have No Consequence for Cerebral Microvascular Integrity and Cognitive Function in Young Healthy Mice.

Diabetes and other age-related diseases are associated with an increased risk of cognitive impairment, but the underlying mechanisms remain poorly understood. Methylglyoxal (MGO), a by-product of glycolysis and a major precursor in the formation of advanced glycation end-products (AGEs), is increased in individuals with diabetes and other age-related diseases and is associated with microvascular dysfunction. We now investigated whether increased levels of circulating MGO can lead to cerebral microvascular dysfunction, blood-brain barrier (BBB) dysfunction, and cognitive impairment. Mice were supplemented or not with 50mM MGO in drinking water for 13weeks. Plasma and cortical MGO and MGO-derived AGEs were measured with UPLC-MS/MS. Peripheral and cerebral microvascular integrity and inflammation were investigated. Cerebral blood flow and neurovascular coupling were investigated with laser speckle contrast imaging, and cognitive tests were performed. We found a 2-fold increase in plasma MGO and an increase in MGO-derived AGEs in plasma and cortex. Increased plasma MGO did not lead to cerebral microvascular dysfunction, inflammation, or cognitive decline. This study shows that increased concentrations of plasma MGO are not associated with cerebral microvascular dysfunction and cognitive impairment in healthy mice. Future research should focus on the role of endogenously formed MGO in cognitive impairment.

Images in Vascular Medicine: Analysis of skin microvascular dysfunction in Harlequin syndrome using laser speckle contrast imaging.

Images in Vascular Medicine: Analysis of skin microvascular dysfunction in Harlequin syndrome using laser speckle contrast imaging.

HouShiHeiSan attenuates sarcopenia in middle cerebral artery occlusion (MCAO) rats

Ethnopharmacological relevancePhysical therapy is the main clinical treatment for limb symptoms after ischemic stroke, and there is a lack of reliable drug intervention programs. HouShiHeiSan (HS)comes from “Synopsis of the Golden Chamber”, where it is recorded: “seauelae of wind stroke and heaviness of limbs”, indicating this formulae is a promising opion for clinical practice. Aim of the studyThe aim of this study is to explore the therapeutic effect of HS on sarcopenia after ischemic stroke (ISS) by using the middle cerebral artery occlusion (MCAO) rats. Materials and methodsAfter 7 days of adaptive feeding Sprague-Dawley (SD) rats were randomly divided into sham and MCAO surgery groups. After MCAO operation, the agreement of the models was evaluated with a laser speckle instrument, and then, treatment groups were administered HS and related solvent. During the 7 days treatment period, the Zea-Longa score was used to assess the neural function, the treadmill for exercise capacity and traction instrument for grip strength. Besides, the physiological electrical signal system was used to record muscular electrical signals, while the muscle thickness was measured by ultrasound. After data acquisition on the 7th day after MCAO operation, the soleus muscle was dissected, and the indexes of length, weight of whole muscle tissue and cross-sectional area of muscular cells by H&E were recorded. Subsequently, mechanistic indicators were examined. MuRF1 and MAFbx expression was detected by immunohistochemistry (IHC). Furthermore, the expression level of more related indicators of muscular differentiation and cellular proterin balance, including mTOR, p-mTOR, AKT, p-AKT, p70s6k, p-p70s6, FOXO1, p-FOXO1, MyoD1, Myostatin, MuRF1 and MAFbx, were tested via Western blot. ResultsHS improved motor performance and promoted muscle regeneration in MCAO rats. In terms of motor ability, HS mixed with alcohol significantly improved the neurological function damage, reduce the weight loss, increase the running distance per unit time and increase the grip strength. The postoperative muscle electrical signal intensity increased, and muscle thickness, weight, and length were maintained. The HS with alcohol group significantly maintained the cross-sectional size of muscle cells and reduced the number of MyoD1 and myostatin-positive cells in the muscle tissue. It simultaneously promoted the expression of p-mTOR, p-AKT, p-p70s6k, and MyoD1 to promote the synthesis of muscle proteins and inhibited the expression of p-FOXO1, myostatin, MAFbx, and MuRF1 to reduce muscle protein degradation. ConclusionHS can enhance muscle protein synthesis and decrease protein breakdown by activating the AKT/mTOR/FOXO1 pathway, thereby preserving muscle health and enhancing motor performance following stroke in rats.

Machine Learning-Based Approach towards Identification of Pharmaceutical Suspensions Exploiting Speckle Pattern Images

Parenteral artificial nutrition (PAN) is a lifesaving medical treatment for many patients worldwide. Administration of the wrong PAN drug can lead to severe consequences on patients’ health, including death in the worst cases. Thus, their correct identification, just before injection, is of crucial importance. Since most of these drugs appear as turbid liquids, they cannot be easily discriminated simply by means of basic optical analyses. To overcome this limitation, in this work, we demonstrate that the combination of speckle pattern (SP) imaging and artificial intelligence can provide precise classifications of commercial pharmaceutical suspensions for PAN. Towards this aim, we acquired SP images of each sample and extracted several statistical parameters from them. By training two machine learning algorithms (a Random Forest and a Multi-Layer Perceptron Network), we were able to identify the drugs with accurate performances. The novelty of this work lies in the smart combination of SP imaging and machine learning for realizing an optical sensing platform. For the first time, to our knowledge, this approach is exploited to identify PAN drugs.

Mixed Gangliocytoma-Pituitary Adenoma: Incidental Discovery During Eye Injury Evaluation: A Case Study

Abstract Introduction/Objective Mixed gangliocytoma-adenoma is exceedingly rare, representing less than 0.5% of sellar tumors. We present a unique case of mixed gangliocytoma-pituitary adenoma incidentally diagnosed during the evaluation of traumatic eye injury. We aim to clarify the diagnostic process using real clinical data, stressing how such cases might be missed without careful histopathological examination Methods/Case Report A 32-year-old male presented for elective transsphenoidal resection (TSR) due to a suspected growth hormone (GH) secreting pituitary tumor. Surprisingly, the adenoma was discovered incidentally during an eye injury evaluation. Referred from an ophthalmology clinic, initial concerns were a possible blood clot or foreign body in the left eye, following a forceful encounter with a tree branch Results (if a Case Study enter NA) Imaging incidentally identified a 2 cm pituitary mass. Further evaluation showed elevated levels of insulin-like growth factor 1 (IGF1) at 1162 ng/ml and GH at 10.2 ng/ml. Remarkably, the patient had not observed signs of acromegaly, until photographic comparison between past and present appearances was made. TSR of the pituitary mass was done. Microscopic examination revealed monomorphic cells with round nuclei with the typical speckled chromatin pattern of neuroendocrine cells with cytoplasm ranging from chromophobic to eosinophilic, consistent with pituitary adenoma. An additional unexpected finding was the presence of large gangliocytic cells (large neurons), dispersed throughout the tumor as single or clustered cells. In some regions, distinct patches of fine neuropil stroma were associated with the clustered ganglion cells. IHC staining with synaptophysin and neurofilament highlighted the gangliocytic component. CAM 5.2 IHC stain showed perinuclear dot-like expression in the adenoma cells, GH IHC showed patchy expression, and prolactin IHC was expressed in scattered cells. Ki67 index was ~ 2%. There was no evidence of necrosis nor mitosis. The coexistence of sellar gangliocytoma with pituitary adenoma, as observed in this case, represents a rare entity known as mixed gangliocytoma-pituitary adenoma Conclusion The adenomatous component of mixed gangliocytoma-pituitary adenoma often secrete GH, leading to its classification as pituitary somatotroph adenoma. This poses a diagnostic challenge due to the lack of specific symptoms or unique brain imaging features, necessitating thorough histological evaluation for precise diagnosis and to ensure the gangliocytoma component is not overlooked

Persistent Na + current couples spreading depolarization to seizures in Scn8a gain of function mice.

Spreading depolarization (SD) is a slowly propagating wave of massive cellular depolarization that transiently impairs the function of affected brain regions. While SD typically arises as an isolated hemispheric event, we previously reported that reducing M-type potassium current (I KM ) by ablation of Kcnq2 in forebrain excitatory neurons results in tightly coupled spontaneous bilateral seizure-SD complexes in the awake mouse cortex. Here we find that enhanced persistent Na + current due to gain-of-function (GOF) mutations in Scn8a (N1768D/+, hereafter D/+) produces a similar compound cortical excitability phenotype. Chronic DC-band EEG recording detected spontaneous bilateral seizure-SD complexes accompanied by seizures with a profound tonic component, which occurs predominantly during the light phase and were detected in the mutant mice across ages between P40-100. Laser speckle contrast imaging of cerebral blood flow dynamics resolved SD as bilateral wave of hypoperfusion and subsequent hour-lasting hypoperfusion in Scn8a D/+ cortex in awake head-restrained mice subjected to a subconvulsive PTZ. Subcortical recordings in freely moving mice revealed that approximately half of the spontaneous cortical seizure-SD complexes arose with concurrent SD-like depolarization in the thalamus and delayed depolarization in the striatum. In contrast, SD-like DC potential shifts were rarely detected in the hippocampus or upper pons. Consistent with the high spontaneous incidence in vivo , cortical slices from Scn8a D/+ mice showed a raised SD susceptibility, and pharmacological inhibition of persistent Na + current (I NaP ), which is enhanced in Scn8a D/+ neurons, inhibited SD generation in cortical slices ex vivo , indicating that I NaP contributes to SD susceptibility. Ex vivo Ca 2+ imaging studies using acute brain slices expressing genetic Ca 2+ sensor (Thy1-GCAMP6s) demonstrated that pharmacological activation of I KM suppressed Ca 2+ spikes and SD, whereas I KM inhibitor drastically increased the frequency of Ca 2+ spikes in the hippocampus of Scn8a D/+ mice, but not in WT, suggesting that I KM restrains the hyperexcitability resulting from Scn8a GOF mutation. Together, our study identifies a cortical SD phenotype in Scn8a GOF mice shared with the Kcnq2 - cKO model of developmental epileptic encephalopathy and reveals that an imbalance of non-inactivating inward and outward membrane currents bidirectionally modulates spatiotemporal SD susceptibility.

Exposure to Gold Induces Autoantibodies against Nuclear Antigens in A.TL Mice.

To demonstrate causation or/and assess pathogenic mechanisms of environment-induced autoimmunity, various animal models that mimic the characteristics of the human autoimmune diseases need to be developed. Experimental studies in mice reveal the genetic factors that contribute to autoimmune diseases. Here, the immune response of two mouse strains congenic for non-H-2 genes, A.TL (H-2tl) and A.SW (H-2s), was evaluated after 15 weeks' exposure to gold aurothiomalate (AuTM). AuTM-treated A.TL mice showed anti-nuclear antibodies (ANA) with homogenous and/or fine speckled staining patterns and serum autoantibodies to ds-DNA, chromatin, histones, and ribonucleoproteins (RNP). Female A.TL mice showed a stronger immune response than males, as well as an increase of B cells in their spleen after 15 weeks of gold exposure. A.SW exposed for AuTM showed the induction of anti-nucleolar antibodies (ANoA) with a clumpy staining pattern, as well as an increase in splenic B and T cells. The serum autoantibodies levels in A.SW mice were limited compared to those of A.TL mice. Overall, A.TL presents a stronger immune response after gold exposure than A.SW. The immune response developed in A.TL presents similarities with the clinical manifestations in human autoimmune diseases. Thus, gold-exposed A.TL could constitute a potential experimental mouse model for the study of autoimmunity.

Feature comparison from laser speckle imaging as a novel tool for identifying infections in tomato leaves

In the present work we propose the use of laser speckle imaging as non-invasive and marker-free qualitative technique that highlights significant differences between healthy and diseased leaves through image analysis. We observed distinct visual variations, indicating the detectable impact of viral infection on leaf structure. Additionally, leaves tend to homogenize visually over time due to degradation, as evidenced by decreased measured feature vector distances after a week. Statistical analyses, including MANOVA and ANOVA, underscored the significance of parameters like contrast, energy, and variance in distinguishing leaf health states. These findings emphasize the potential of laser speckle imaging for plant health monitoring. Furthermore, our results validate the utility of Apple's Vision library, specifically the VNGenerateImageFeaturePrintRequest() function, as a powerful tool for plant disease diagnosis and health tracking.

ZnO modified carbon fiber-matrix interfacial evaluation via nanoscale digital image correlation and nanoindentation

Improving the adherence of the fiber-matrix interface is an important step for enhancing the capabilities of polymer composites. In this study, carbon fibers were modified by growing zinc oxide (ZnO) nanorods on the fiber surface using a hydrothermal approach, with the aim of increasing the interfacial area and enhancing the friction between the fiber and the matrix. To fully understand the deformation mechanisms at the interface, a microscale evaluation combining nanoindentation with digital image correlation (DIC) for mapping the deformations by using nanoscale speckles is developed in this work. The main objective of this research was to develop a protocol for speckling the modified single fiber composite and show that DIC can be used in microscopic level and to evaluate the fiber-matrix interface by means of nano indentation. The speckle pattern was created using Ti nano powder and used to generate the strain maps in the fiber-matrix interface region. A comparative analysis of DIC results from ZnO modified carbon fibers has shown that shear strains around the interfacial boundary are 60 % reduced on average, as compared to neat carbon fibers, across all nano indentations from 8mN to 65mN of peak load. Results used direct strain measurements to confirm that modification by ZnO growth on the surface of individual fibers has a significant benefit to the interfacial mechanical properties of fiber-matrix composites.

Statistical assessment of the inner shape of a channel based on laser speckle contrast imaging

In this work, we employed laser speckle contrast imaging coupled with the analysis of several statistical moments on the recorded images to recognize the shape of an object through the analysis of the pattern of a flow around it. We postulated that a flow through different geometries would generate a unique flow structure and thus the mathematical analysis of the differences can be utilized to detect and recognize various shape geometries. To this aim, the flow of scattered liquid that had passed through objects of different shapes was illuminated by a laser beam and the diffused speckle image was recorded by a camera. In the computer, the captured speckle image was first converted to a flow image and then mathematically analyzed to recognize the shape of the objects. Three out of the eight statistical metrics were found to be the best candidates for the recognition of shapes, thus proving our hypothesis.

Study of age-related retinal hemodynamic changes by laser speckle flowgraphy

Background: Diagnostics of hemodynamic changes is important both for clarifying the features of the course of pathological process of many ophthalmic diseases and for optimizing treatment tactics. Laser speckle flowgraphy (LSFG) is a new non-invasive method for quantitative assessment of retinal blood flow. Aim: To study age-related changes of pulse waves both in large blood vessels and microvasculature in the optic nerve head and macula by laser speckle flowgraphy. Materials and methods: Age-related changes in blood flow were studied in 60 healthy volunteers using LSFG-RetFlow. We analyzed MBR — main parameter of pulse wave assessed by the laser speckle flowgraphy and also another 8 pulse wave parameters for large vessels and microvasculature in the areas of optic nerve head and macula. Results: The study revealed statistically significant (p ≤ 0.05) age-related changes in pulse waves for most parameters under study. In the large vessels of the optic disc blood flow dropped after 60 years, while in the microvasculature it decreased progradiently in the groups older than 40 and 60 years. In the macular region, blood flow in large vessels and microvasculature decreased mainly in the group aged over 61. Age-related changes in pulse wave parameters were unidirectional for both large vessels and microvasculature; trends were similar in both areas under investigation. Conclusions: The study demonstrated statistically significant (age-related changes in most laser speckle flowgraphy pulse wave parameters. The MBR, MV (MBR of Vascular area), MT (MBR of Tissue area) indicators are most informative in the ophthalmic hemodinamic screening. The study of another pulse wave parameters seems sufficient for the general MBR.

Eye microcirculation in glaucoma. Part 1. Diagnostic methods

Glaucoma is a socially significant disease, which is a wide group of polyetiological diseases. In the etiology of primary glaucoma, in addition to the mechanical theory, a vascular mechanism is also distinguished, and therefore, the search and development of the most informative and accurate method for studying ocular blood flow continues. Existing methods are divided into invasive and non-invasive. Invasive methods include angiography with intravenous fluorescein and indocyanine. Non-invasive methods include ultrasound Doppler mapping and pulsed Doppler modes, optical coherence tomography with angiography and laser speckle flowography. The review presents data on modern methods for ocular hemodynamics in glaucoma and ocular hypertension with technologies for studying retrobulbar blood flow and intraocular hemocirculation.