Search Results (409)

Background/Objectives: Diabetic macular edema (DME) is the primary cause of vision loss in people with diabetes, and if untreated, it can result in irreversible macular damage. Both fluorescein angiography (FA), the gold standard, and optical coherence tomography angiography (OCTA) are used for evaluation of this disease. The objective of this study was to compare the diagnostic value of both. Methods: We conducted a comparative analysis of 98 patients aged 18–80 years with significant DME and best-corrected visual acuity ≥0.1 according to the Snellen chart. Participants underwent glycated hemoglobin blood test (HbA1c) and ophthalmological examinations, including OCTA and FA. OCTA 3 × 3 mm scans of superficial (SCP) and deep capillary plexus (DCP) along with FA scans were exported to the Gimp computer program. Size of the foveal avascular zone (FAZ), the number of visible microaneurysms (MAs), and ETDRS report number 11 classification of the images were assessed. Results: FAZ size differed significantly in superficial plexus (0.41 mm²), deep plexus (0.43 mm²) OCTA, and FA (0.38 mm²) (p < 0.001). FAZ size in DCP OCTA closely correlated with that of FA (τ = 0.79, p < 0.001). The total number of MAs visualized in the OCTA was significantly lower than in FA (p < 0.001). ETDRS classification of scans revealed that the level of consistency between the examinations was moderate to very strong. Conclusions: OCTA may be useful in evaluating macular ischemia. It is less sensitive in detecting MAs in DME eyes. FAZ has sharper boundaries and is larger when measured in OCTA. Poor glycemic control results in higher incidence of MAs in macula. Full article

Background: This study aimed to evaluate retinal arteriole parameters using adaptive optics (AO) rtx1™ (Imagine Eyes, Orsay, France) and peripapillary and macular vessel densities with optical coherence tomography angiography (OCTA) in eyes with different stages of primary open-angle glaucoma (POAG) compared to healthy eyes. It also investigated the associations between vascular parameters and glaucoma severity, as defined by structural (OCT) and functional (visual field) changes. Methods: Fifty-seven eyes from 31 POAG patients and fifty from 25 healthy volunteers were examined. Retinal arteriole morphology was assessed using the AO rtx1™-fundus camera, which measured lumen diameter, wall thickness, total diameter, wall-to-lumen ratio (WLR), and wall cross-sectional area. OCTA was used to measure vessel densities in superficial (SCP) and deep (DCP) capillary plexuses of the macula and radial peripapillary capillary plexus (RPCP) and FAZ area. Structural OCT parameters (RNFL, GCC, rim area) and visual field tests (MD, PSD) were also performed. Results: Glaucoma eyes showed significantly thicker arteriole walls (12.8 ± 1.4 vs. 12.2 ± 1.3 µm; p = 0.030), narrower lumens (85.5 ± 10.4 vs. 100.6 ± 11.1 µm; p < 0.001), smaller total diameters (111.0 ± 10.4 vs. 124.1 ± 12.4 µm; p < 0.001), and higher WLRs (0.301 ± 0.04 vs. 0.238 ± 0.002; p < 0.001) than healthy eyes. In glaucoma patients, OCTA revealed significantly reduced vessel densities in SCP (36.39 ± 3.60 vs. 38.46 ± 1.41; p < 0.001), DCP (36.39 ± 3.60 vs. 38.46 ± 1.41; p < 0.001), and RPCP plexuses (35.42 ± 4.97 vs. 39.27 ± 1.48; p < 0.001). The FAZ area was enlarged in eyes with glaucoma (0.546 ± 0.299 vs. 0.295 ± 0.125 mm²); p < 0.001). Positive correlations were found between vessel densities and OCT parameters (RNFL, r = 0.621; GCC, r = 0.536; rim area, r = 0.489), while negative correlations were observed with visual field deficits (r = −0.517). Conclusions: Vascular deterioration, assessed by AO rtx1™ and OCTA, correlates closely with structural and functional damage in glaucoma. Retinal microcirculation changes may precede structural abnormalities in the optic nerve head. Both imaging methods enable the earlier detection, staging, and monitoring of glaucoma compared to conventional tests. Full article

Curvilinear V-grooves are increasingly employed in functional surfaces with applications ranging from fluidics to tribology and optics. Despite their widespread use, the accurate and repeatable fabrication of curvilinear V-grooves remains challenging due to their inherent geometric complexity and the lack of relevant commercial CAD/CAM systems. To address this, the present study proposes a CAD/CAM integrated framework capable of automating the design and fabrication of functional surfaces comprising curvilinear V-grooves generated by multi-axis single-point diamond cutting (SPDC). The framework is organized into three main functional blocks supported by seven secondary modules that encompass the entire process from V-groove geometry definition to cutting. The developed framework was practically validated by fabricating sinusoidal V-grooves on a flat surface and testing the capillary flow functionality of a curvilinear pattern. These results demonstrate the relevance of the integrated framework to curvilinear V-groove fabrication, thereby offering a versatile solution for certain types of surface engineering applications. Full article

Background/Objectives: To investigate the role of multimodal imaging, specifically optical coherence tomography angiography (OCTA) and adaptive optics (AO), in the diagnosis and monitoring of diabetic retinopathy. Methods: Our study represents an observational, cross-sectional analysis including sixty-nine patients from four distinct groups: a control group (17 patients), diabetic patients without diabetic retinopathy (no DR) (14 patients), diabetic patients with non-proliferative diabetic retinopathy (NPDR) (18 patients), and diabetic patients with proliferative diabetic retinopathy (PDR patients). A comprehensive ophthalmological evaluation, along with high-resolution imaging using OCTA and AO, was performed. OCTA images of the superficial capillary plexus, acquired with the OCT Angio Topcon, were analyzed using a custom-developed MATLAB algorithm, while AO retinal vascular images were evaluated with the manufacturer’s software of the Adaptive Optics Retinal Camera rtx1™. Results: Our findings demonstrated statistically significant reductions in foveal avascular zone circularity, superficial capillary plexus density, vessel length density, and fractal dimension, correlating with the severity of diabetic retinopathy, particularly in the PDR. Additionally, mean wall thickness and wall-to-lumen ratio were significantly increased in patients with diabetic retinopathy, notably in PDR. Conclusions: In conclusion, our findings demonstrate that the combined use of OCTA and AO imaging offers complementary insights into the microvascular alterations associated with diabetic retinopathy progression and severity. These high-resolution modalities together reveal both perfusion deficits and structural vascular changes, underscoring their utility as essential tools for early detection, staging, monitoring, and informed management of DR. Full article

Background/Objectives: This study investigates the macular microvasculature in a large cohort of primary Sjögren’s disease (SjD) patients using optical coherence tomography angiography (OCTA), focusing on how disease duration, activity, and hydroxychloroquine (HCQ) treatment influence retinal microcirculation. Methods: A total of 106 eyes (53 SjD patients) and 70 eyes (35 age- and gender-matched healthy controls (HCs)) were examined. The vessel area density (VAD, %) and foveal avascular zone (FAZ, mm2) were measured in three retinal layers: Superficial Vascular Plexus (SVP), Intermediate Capillary Plexus (ICP), and Deep Capillary Plexus (DCP), respectively, in three peri-macular circular sectors (c1, c2, c3) each. Results: The VAD was significantly lower in c1 of the DCP in SjD compared to HCs (29.14 ± 7.07 vs. 31.78 ± 9.55, p = 0.038). The FAZ was significantly larger in SjD in both SVP (0.41 ± 0.13 vs. 0.34, 0.11, p < 0.001; Cohen’s |d| = 0.55) and DCP (0.45 ± 0.15 vs. 0.4 ± 0.14, p = 0.014; Cohen’s |d| ± 0.38). Significant correlations were observed between the FAZ size and reductions in the VAD in the SVP and DCP (p = 0.010, Cohen’s |d| = 0.2; p < 0.001, Cohen’s |d| ± 0.26) and across all layers combined (p = 0.019, Cohen’s |d| = −0.18). Conclusions: There was a negative correlation between the VAD in the DCP and disease duration (ρ = −0.28, p = 0.040). No significant correlation was identified between the duration of HCQ intake and the VAD or FAZ. Our findings indicate microvascular alterations in the DCP of SjD, characterized by a reduced VAD and an enlarged FAZ, which may be attributable to inflammatory or arteriosclerotic factors. OCTA may prove to be a valuable tool for the stratification of vascular risk in SjD. Full article

Purpose: Varicella zoster virus (VZV) vasculopathy can occur in patients with herpes zoster (HZ). Our aim was to evaluate the retinal microvascular vessel density (VD) in patients with trigeminal HZ measured by optical coherence tomography angiography (OCTA). Methods: 48 eyes of 24 patients with HZ and 48 eyes of 24 healthy age- and gender-matched controls were included in this study. All participants underwent an OCTA examination using RTVue XR Avanti with AngioVue. The VD data of the macular 3 × 3 mm OCT angiogram of the superficial capillary plexus (SCP), the deep capillary plexus (DCP), and the choriocapillaris (CC) as well as the VD data of the optic nerve head (ONH) were extracted and analyzed. Results: The VD in the SCP, DCP, and CC of patients with HZ was significantly lower compared with healthy controls (p < 0.05). Equally, there was a noticeable reduction in the inside disk area of the ONH. There was no statistically noticeable reduction in the FAZ area and central retinal thickness. Conclusions: In this study, HZ patients demonstrated a decrease in the retinal VD of the SCP, DCP, ONH, and the CC. Quantitative analysis of retinal perfusion using OCTA may therefore help in the diagnosis and monitoring of HZ. Further studies must show to what extent this may be an indication of VZV-related vasculopathy and whether OCTA data can be used as a biomarker in these patients in the future. Full article

Our study aimed to assess the anatomical changes in the retina, including the assessment of the reduction of diabetic macular edema (DME) on optical coherence tomography (OCT) and the improvement of retinal microvascular parameters, defined by the reduction of nonperfusion areas on OCT angiography (OCTA) after intravitreal injections of 6 mg faricimab, an anti-VEGF drug used in the treatment of DME. The study included twenty-two patients aged between 61 and 74 years, each of whom received four loading doses of 6 mg faricimab at 1-month intervals, as described in the summary of product characteristics. Hemodynamic parameters were analyzed by OCT angiography before the first intravitreal injection of faricimab and one month after each subsequent injection. The following parameters were analyzed: non-perfusion area (NPA), superficial capillary plexus (SCP) and deep capillary plexus (DCP), outer retinal flow area (ORFA), choriocapillaris flow area (CCFA) and foveal avascular zone (FAZ). Despite differences in the magnitude of improvement and time to improvement from the start of treatment with intravitreal injections of 6 mg faricimab, reductions in DME and improvements in OCTA parameters resulted in increased retinal blood flow and better visual acuity. Full article

Background/Objectives: The aim of this study was to investigate quantitative differences in optical coherence tomography angiography (OCTA) between diabetic patients and healthy controls and to identify the early OCTA biomarkers for diabetic macular changes. Methods: Ophthalmological examination and OCTA were performed on two groups of diabetic patients (with and without mild diabetic retinopathy) and healthy controls. Macular, foveal, perifoveal, and parafoveal vessel density (VD) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), foveal avascular zone (FAZ), and flow area in the choriocapillaris were calculated. Results: A total of 431 eyes of 233 participants were analyzed. The VD in the SCP in the whole macula was the lowest in the DM + DR group and lower than in the DMnoDR group; however, in the fovea, it was the highest in the DM + DR group and higher than in the DMnoDR group. The VD in the SCP in the parafovea was lower in the DM + DR group than in the DMnoDR group, and in the perifovea, it was lower in the DMnoDR group than in the control group. The VD in the DCP in the macula, parafovea, and perifovea was lower in the DM + DR group than in the DMnoDR and control groups. The FAZ and flow areas in the choriocapillaris were smaller in the DM + DR group than in both the DMnoDR and control groups. Conclusions: VD reduction in the SCP and the DCP of the macular and parafoveal regions, as well as in the DCP of the perifoveal region, may indicate progression of diabetic retinopathy from subclinical to clinical stages; however, an increase in the foveal region in the SCP can be a compensatory mechanism. VD reduction in the perifovea and whole macula in the SCP can be a screening factor for subclinical macular changes. FAZ reduction before clinical signs of retinopathy may be an early compensatory vascular mechanism. Full article

Background/Objectives: The retinal microvasculature may reflect systemic vascular health and can be non-invasively imaged using optical coherence tomography angiography (OCTA). Investigation of the capillary plexuses in the macula and the peripapillary area could potentially provide insights into the pathophysiology of ocular manifestations in preeclampsia. We aimed to review the literature on OCTA metrics in preeclampsia to evaluate its use in this condition. Methods: A literature search was performed using the PubMed database, and studies published up to December 2024 were included. Results: We summarized the current evidence on chorioretinal microvascular changes in pregnancy and the ocular manifestations of preeclampsia. We reported findings from seven published studies characterizing the chorioretinal capillary plexuses in preeclampsia using OCTA. These revealed changes in microvasculature characteristics, such as foveal avascular zone size and vessel density in the macula and the peripapillary area; however, there was variability in reported parameters. Conclusions: Microvascular changes in the chorioretinal capillary plexus in preeclampsia were reported by several studies; however, results were inconsistent and may have been affected by multiple factors. Nevertheless, OCTA may have diagnostic and prognostic value, by providing evidence of microcirculation sequalae and aiding our understanding of ocular manifestations in this condition. Further studies are warranted to establish appropriate OCTA acquisition protocols and metrics, and whether these could guide clinical practice in preeclampsia. Full article

Exploring innovative approaches to enhance the performance of photonic lanterns is greatly valuable. In this paper, we first propose an air-hole-assisted pure silica-based capillary (AHC), featuring a single ring of embedded air holes. As a result, the PL based on the AHC exhibits good performance, successfully exciting LP₀₁, LP_11a & LP_11b, LP_21a & LP_21b, LP₀₂, and LP_31a & LP_21b modes. The average mode loss, mode-dependent loss, and maximum crosstalk are 0.08 dB, 0.04 dB, and −27.2 dB, respectively. In fact, the overall performance of the proposed AHC-based PL is on par with that of the traditional PL. Furthermore, an error analysis is provided to confirm the feasibility of our approach. The AHC-based PLs possess high numerical apertures and are expected to enable high spatial resolution imaging in optical imaging. Full article

Miniaturization and reliable, real-time, non-invasive monitoring are essential for investigating microfluidic processes in Lab-on-a-Chip (LoC) systems. Progress in this field is driven by three complementary approaches: analytical modeling, computational fluid dynamics (CFD) simulations, and experimental validation techniques. In this study, we present an on-chip experimental method for estimating the slug-flow velocity in microchannels through in situ optical monitoring. Slug flow involving two immiscible fluids was investigated under both liquid–liquid and gas–liquid conditions via an extensive experimental campaign. The measured velocities were used to determine the slug length and key dimensionless parameters, including the Reynolds number and Capillary number. A comparison with analytical models and CFD simulations revealed significant discrepancies, particularly in gas–liquid flows. These differences are mainly attributed to factors such as gas compressibility, pressure fluctuations, the presence of a liquid film, and leakage flows, all of which substantially affect flow dynamics. Notably, the percentage error in liquid–liquid flows was lower than that in gas–liquid flows, largely due to the incompressibility assumption inherent in the model. The high-frequency monitoring capability of the proposed method enables in situ mapping of evolving multiphase structures, offering valuable insights into slug-flow dynamics and transient phenomena that are often difficult to capture using conventional measurement techniques. Full article

Objectives: To evaluate the short- and long-term effects of subthreshold micropulse laser (SMPL) treatment on the microvascular network in diabetic macular edema (DME). Methods: This 12-month prospective study included 67 eyes (67 patients) with mild DME and good best-corrected visual acuity (BCVA), randomized into SMPL (33 eyes) or sham (34 eyes) groups. Assessments were performed at baseline (T1), 3 months (T2), and 12 months (T3). Optical coherence tomography (OCT) and OCT angiography (OCTA) were used to measure central retinal thickness (CRT), macular thickness (MT), macular volume (MV), foveal avascular zone (FAZ) area, microaneurysm (MA) count, and vessel parameters in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). Results: The SMPL group showed a greater relative reduction in FAZ area in the SCP at 3 months (3.21 ± 13.03% vs. −5.73 ± 13.3%; p = 0.032) with a trend toward significance at 12 months (2.37 ± 12.47% vs. −3.3 ± 7.92%; p = 0.086) compared to the sham group. No changes in FAZ size, MA count, and other microvascular parameters were observed in either group. In the SMPL group, BCVA improved at 3 months (T2 > T1, p = 0.003); CRT decreased at 12 months (T2 > T3, p = 0.023); MT decreased at 12 months (T2 > T3, p = 0.006) and MV decreased at 12 months (T2 > T3, p = 0.007). No changes were detected in the sham group. No treatment-related complications occurred. Conclusions: SMPL may improve the macular microvasculature in mild DME by reducing FAZ size in the SCP. It provides visual and functional benefits while maintaining a favorable safety profile. Full article

Background/Objectives: The aim of this study was to investigate the potential contribution of microaneurysms (MAs) and retinal cysts to the pathogenesis of macular non-perfusion in patients with diabetic macular edema (DME) using multimodal imaging. Methods: In this cross-sectional study, 42 eyes with DME were analyzed using color fundus photography, fluorescein angiography (FA) and optical coherence tomography (OCT). Macular non-perfusion within the central 3000 µm was categorized by location and extent into foveal avascular zone enlargement (FAZE), focal non-perfusion (FNP) and diffuse non-perfusion (DNP). A custom-developed software was used to assess the colocalization of retinal cysts on OCT with areas of non-perfusion on the corresponding FA images. Also, the presence of leaky MAs adjacent to retinal cysts on FA was verified. Results: Colocalization between retinal cysts and non-perfusion was observed in 32 of 42 (76%) eyes: 19 of 23 (83%) eyes with FAZE and 13 of 16 (81%) eyes with FAZE+FNP. No cysts colocalization was found in all three eyes (100%) presenting with DNP. None of the eyes presented with FNP alone. In the remaining seven eyes (four eyes with FAZE and three eyes with FAZE+FNP), no colocalization was noticed. At least one leaky MA adjacent to retinal cysts was identified in all eyes presented with colocalization. Conclusions: Retinal cysts may contribute to the development of limited non-perfusion in DME. Leaky MAs appear to be the primary source of cyst formation, which may lead to localized capillary occlusion in the macula. Full article

Background: Cardiovascular diseases (CVDs) are responsible for 32.4% of all deaths across the European Union (EU), and several CVD risk scores have been developed, with variable results. Retinal microvascular changes have been proposed as potential biomarkers for cardiovascular risk, especially in coronary heart diseases (CHDs). This study aims to identify the retinal microvascular features associated with CHDs and evaluate their potential use in a CHD screening algorithm in conjunction with traditional risk factors. Methods: We performed a two-center cross-sectional study on 120 adult participants—36 patients previously diagnosed with severe CHDs and scheduled for coronary artery bypass graft surgery (CHD group) and 84 healthy controls. A brief medical history and a clinical profile were available for all cases. All patients benefited from optical coherence tomography angiography (OCTA), the use of which allowed several parameters to be quantified for the foveal avascular zone and superficial and deep capillary plexuses. We evaluated the precision of several classification models in identifying patients with CHDs based on traditional risk factors and OCTA characteristics: a conventional logistic regression model and four machine learning algorithms: k-Nearest Neighbors (k-NN), Naive Bayes, Support Vector Machine (SVM) and supervised logistic regression. Results: Conventional multiple logistic regression had a classification accuracy of 78.7% based on traditional risk factors and retinal microvascular features, while machine learning algorithms had higher accuracies: 81% for K-NN and supervised logistic regression, 85.71% for Naive Bayes and 86% for SVM. Conclusions: Novel risk scores developed using machine learning algorithms and based on traditional risk factors and retinal microvascular characteristics could improve the identification of patients with CHDs. Full article

Biosensor technologies in medicine, as in many other areas, are replacing labor-intensive methods of monitoring human health. This paper presents the results of experimental studies on label-free sensors based on a hollow core microstructured optical waveguide (HC-MOW) for human blood serum analysis. The MOWs with a hollow core of 247.5 µm in diameter were manufactured and used in our work. These parameters allow the hollow core to be filled with high-viscosity solutions due to the capillary properties of the fiber. Calculations of the spectral properties of the HC-MOW fiber were carried out and experimentally confirmed. Twenty-one blood serum samples from volunteers were analyzed using standard photometry (commercial kits) and an experimental biosensor. The obtained transmission spectra were processed by the principal component analysis method and conclusions were drawn about the possibility of using this biosensor in point-of-care medicine. A significant difference was shown between the blood serum of healthy patients and patients with confirmed diagnoses and a long history of cardiovascular system abnormalities. Algorithms for spectra processing using the Origin program are presented. Full article