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Influence of the pulse duration at near-infrared wavelengths on the laser-induced material removal of hot-dipped galvanized steel
摘要： Hot-dipped galvanized steel is processed with short- and ultrashort-pulsed lasers in air at near-infrared wavelengths with pulse durations ranging from 350 fs to 241 ns. The morphology of the ablated craters (processed over a range of laser fluence levels and a number of laser pulses) is analyzed by confocal laser scanning microscopy and scanning electron microscopy. The ablation threshold of galvanized steel is found to increase with laser pulse durations following a simple power Fth ? A:τB law. Longer pulse durations in the nanosecond regime, as compared to pulse durations in the picosecond and femtosecond regime, result in higher ablation efficiency and energy penetration depth at the cost of surface quality.
关键词： ablation efficiency,ultrashort-pulsed laser,galvanized steel,ablation threshold,rim
更新于2025-09-23 15:19:57
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The Relationship Between Retinal Nerve Fiber Layer Thickness and Optic Nerve Head Neuroretinal Rim Tissue in Glaucoma
摘要： PURPOSE. The purpose of this study was to determine the relationship between optical coherence tomography (OCT) measures of retinal nerve fiber layer (RNFL) and neuroretinal rim (NRR) in a nonhuman primate experimental glaucoma model, and in a population of clinical patients. METHODS. For nonhuman primates, normative data were collected from 44 healthy monkeys, and nine animals with unilateral experimental glaucoma that were followed longitudinally. Cross-sectional human subjects data were collected from 89 healthy, 74 glaucoma suspects, and 104 glaucoma patients. Individualized transverse scaling for OCT scans was calculated using a schematic eye that incorporated optical ocular biometry. Custom algorithms were used to quantify RNFL thickness with and without vessels removed, scaled minimum rim width (sMRW), and neural rim volume (NRV). RESULTS. For the experimental glaucoma group, NRR parameters showed the first changes with increased cumulative IOP. The data for both NRR and RNFL measures were best fit by an exponential rise model (NRV, R2 ? 0.79, P < 0.01, sMRW, R2 ? 0.74, P < 0.01). The major retinal vascular thickness contribution to the RNFL decreased (0.03 lm/lm, P < 0.01) with RNFL loss, but the percent vascular contribution increased ((cid:2)0.1%/lm, P < 0.01) with disease progression. Overall, the findings for the cross-sectional human data were similar to those of the experimental model. CONCLUSIONS. The findings illustrate a nonlinear relationship between NRR and RNFL measures and provide support for the use of multiple OCT scaled morphological measures for the diagnosis and management of primary open angle glaucoma in humans.
关键词： glaucoma,neuroretinal rim,RNFL,optical coherence tomography
更新于2025-09-19 17:15:36
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Clinical relevance of protruded retinal layers in minimum rim width measurement of the optic nerve head
摘要： background/aims Optical coherence tomography (OCT) imaging of the optic nerve head minimum rim width (MRW) has recently been shown to sometimes contain components besides extended retinal nerve fibre layer (RNFL). This study was conducted to determine whether excluding these components, termed protruded retinal layers (PRLs), from MRW increases diagnostic accuracy for detecting glaucoma. Methods In this cross-sectional study, we included 123 patients with glaucoma and 123 normal age-similar controls with OCT imaging of the optic nerve head (24 radial scans) and RNFL (circle scan). When present, PRLs were manually segmented, and adjusted MRW measurements were computed. We compared diagnostic accuracy of adjusted versus unadjusted MRW measurement. We also determined whether adjusted MRW correlates better with RNFL thickness compared with unadjusted MRW. results The median (IQR) visual field mean deviation of patients and controls was ?4.4 (?10.3 to ?2.1) dB and 0.0 (?0.6 to 0.8) dB, respectively. In the 5904 individual B-scans, PRLs were identified less frequently in patients (448, 7.6%) compared with controls (728, 12.3%; p<0.01) and were present most frequently in the temporal sector of both groups. Areas under the receiver operating characteristic curves and sensitivity values at 95% specificity indicated that PRL adjustment did not improve diagnostic accuracy of MRW, globally or temporally. Furthermore, adjusting MRW for PRL did not improve its correlation with RNFL thickness in either group. Conclusion While layers besides the RNFL are sometimes included in OCT measurements of MRW, subtracting these layers does not impact clinical utility.
关键词： minimum rim width,OCT imaging,glaucoma,protruded retinal layers,optic nerve head
更新于2025-09-09 09:28:46
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Diagnostic Accuracy of Glaucoma With Sector-Based and a New Total Profile–Based Analysis of Neuroretinal Rim and Retinal Nerve Fiber Layer Thickness
摘要： PURPOSE. To compare the diagnostic accuracy of conventional sector-based analysis with a method devised to detect the smallest localized neuroretinal rim and retinal nerve fiber layer thickness (RNFLT) damage. METHODS. One eye of 151 glaucoma patients and 83 healthy controls (median age and MD, 71.7 and 66.7 years, and (cid:2)3.6 and (cid:2)0.3 dB, respectively) was imaged with spectral-domain optical coherence tomography (OCT). Bruch’s membrane opening-minimum rim width (BMO-MRW) and RNFLT were determined at 18 intervals and also averaged for each sector. A classification of glaucoma was made with sectoral analysis when the sectoral value was below the 1%, 5%, or 10% normative limit (from an independent normative dataset); and with total analysis when a given number of measurements was below the 1%, 5%, or 10% normative limit. RESULTS. With the 1% normative limit, BMO-MRW sectoral analysis yielded sensitivity of 87% and specificity of 92%; while at the same specificity (92%), total analysis yielded sensitivity of 88%. With RNFLT, sectoral analysis yielded sensitivity of 85% and specificity of 95%; while at the same specificity (95%), total analysis yielded sensitivity of 83%. The results for the 5% and 10% normative limits yielded lower specificity but higher sensitivity. In the whole glaucoma population, none of the sensitivity values of the sectoral and total analysis at the same specificities were statistically different. CONCLUSIONS. The diagnostic accuracy of sectoral analysis was equivalent to total analysis. These results indicate that BMO-MRW and RNFLT defects were wide and deep enough for detection by conventional sectoral analysis.
关键词： diagnostic accuracy,neuroretinal rim,retinal nerve fiber layer
更新于2025-09-09 09:28:46
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Correlation between optic nerve head structural parameters and glaucomatous visual field indices
摘要： We examined associations between optic nerve head structural parameters and glaucomatous visual field indices. The study population included patients with glaucomatous optic neuropathy who were evaluated at Aichi Medical University, Nagakute, Aichi, Japan, from October 2010 to January 2011. A total of 57 eyes from 33 patients were assessed. We measured visual field using a Humphrey field analyzer, peripapillary retinal nerve fiber layer thickness (RNFL-T), and Bruch’s membrane opening-minimum rim width (BMO-MRW) using spectral domain optical coherence tomography, and rim area with referring three-dimensional photography. Spearman’s rank correlation coefficients were calculated between the threshold of visual sensitivity or total deviation of visual field and the following five optic nerve head structural parameters: RNFL-T length, BMO-MRW length, rim area, and calculated RNFL-T and BMO-MRW volumes (each length multiplied by rim area). The Akaike information criterion was calculated to determine which structural parameter was the best predictor of each visual field index. Threshold of visual sensitivity had correlation coefficients of 0.23 with global sector of RNFL-T, 0.32 with BMO-MRW, 0.14 with rim area, 0.21 with RNFL-T volume, and 0.26 with BMO-MRW volume. The correlation coefficients for each parameter with total deviation of visual field were 0.22, 0.33, 0.28, 0.36, and 0.37, respectively. The Akaike information criterion of BMO-MRW showed the smallest values in analyses of both threshold of visual sensitivity and total deviation. The present results show that RNFL-T volume and BMO-MRW volume were more strongly correlated with total deviation than BMO-MRW, but BMO-MRW appeared to be the best predictor of the two glaucomatous visual field indices.
关键词： retinal nerve fiber layer thickness,rim area,visual field,glaucoma,spectral domain optical coherence tomography,Bruch’s membrane opening-minimum rim width
更新于2025-09-04 15:30:14
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - 3rd generation rim drive heliostat with monolithic sandwich panel
摘要： The improvements of the mechanical structure of the current rim drive heliostat generation with chain drive system and monolithic sandwich structure is described. The improvements of the mechanical structure result in increased torsional stiffness of the pylon, reduced manufacturing effort, increased life time of the chain gears, and better access to the drives. Dynamic wind loads were determined by loading a transient finite element model with pressure distribution time series gained by wind tunnel tests. Due to the rims, the heliostat shows significantly better dynamic behavior than conventional heliostats without rims.
关键词： monolithic sandwich panel,rim drive heliostat,dynamic wind loads,chain drive system,torsional stiffness
更新于2025-09-04 15:30:14
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Comprehensive Three-Dimensional Analysis of the Neuroretinal Rim in Glaucoma Using High-Density Spectral-Domain Optical Coherence Tomography Volume Scans
摘要： To describe spectral-domain optical coherence tomography (OCT) methods for quantifying neuroretinal rim tissue in glaucoma and to compare these methods to the traditional retinal nerve fiber layer thickness diagnostic parameter. Neuroretinal rim parameters derived from three-dimensional (3D) volume scans were compared with the two-dimensional (2D) Spectralis retinal nerve fiber layer (RNFL) thickness scans for diagnostic capability. This study analyzed one eye per patient of 104 glaucoma patients and 58 healthy subjects. The shortest distances between the cup surface and the OCT-based disc margin were automatically calculated to determine the thickness and area of the minimum distance band (MDB) neuroretinal rim parameter. Traditional 150-lm reference surface–based rim parameters (volume, area, and thickness) were also calculated. The diagnostic capabilities of these five parameters were compared with RNFL thickness using the area under the receiver operating characteristic (AUROC) curves. The MDB thickness had significantly higher diagnostic capability than the RNFL thickness in the nasal (0.913 vs. 0.818, P ? 0.004) and temporal (0.922 vs. 0.858, P ? 0.026) quadrants and the inferonasal (0.950 vs. 0.897, P ? 0.011) and superonasal (0.933 vs. 0.868, P ? 0.012) sectors. The MDB area and the three neuroretinal rim parameters based on the 150-lm reference surface had diagnostic capabilities similar to RNFL thickness. The 3D MDB thickness had a high diagnostic capability for glaucoma and may be of significant clinical utility. It had higher diagnostic capability than the RNFL thickness in the nasal and temporal quadrants and the inferonasal and superonasal sectors.
关键词： neuroretinal rim,spectral-domain optical coherence tomography,glaucoma,optic disc,optic nerve
更新于2025-09-04 15:30:14
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Influence of uveitis on Bruch’s membrane opening minimum rim width and retinal nerve fibre layer thickness measurements
摘要： background/aims To assess the impact of papillary leakage and active inflammation on optical coherence tomography (OCT)-based retinal nerve fibre layer thickness (RNFLT) and Bruch’s membrane opening minimum rim width (BMO-MRW) measurements in uveitic eyes with and without secondary glaucoma. Methods Prospective, single-centre analysis of patients with uveitis. All patients included received a fluorescein angiography examination and an OCT scan measuring the BMO-MRW and the RNFLT in three concentric peripapillary ring scans. results Overall, 95 eyes of 56 patients were enrolled. Papillary leakage and active inflammation were present in 39 (41%) and 57 (60%) eyes, respectively. Twenty-one eyes were classified as glaucomatous; 10 of those glaucomatous eyes showed papillary leakage. Both BMO-MRW and RNFLT measurements were significantly increased in eyes with papillary leakage (BMO-MRW: p=0.0001; RNFL: first to third ring (p<0.0001)). Active inflammation led to a significantly thickened RNFLT (first ring: p=0.0026; second ring: p=0.0009; third ring: p=0.0002) while only a trend towards increased values could be observed in the BMO-MRW measurements (p=0.3063). Glaucomatous eyes with papillary leakage demonstrated significantly higher values on both BMO-MRW and RNFLT measurements than glaucomatous eyes without leakage (BMO-MRW: p=0.0159; RNFL: first ring: p=0.0062; second ring: p=0.0037; third ring: p=0.0197). No significant difference could be observed between glaucomatous eyes with leakage and non-glaucomatous eyes without leakage (BMO-MRW: p=0.4132; RNFL: first ring: p=0.5412; second ring: p=0.3208; third ring: p=0.1164). Conclusions The OCT scanning parameters BMO-MRW and RNFLT were significantly influenced by papillary leakage in uveitic eyes with and without glaucoma. RNFLT values were also significantly increased while active inflammation was present. In patients with uveitis, these OCT-based imaging tools should be interpreted with caution, especially in those with papillary leakage or active inflammation.
关键词： uveitis,optical coherence tomography,retinal nerve fibre layer thickness,Bruch’s membrane opening minimum rim width,glaucoma
更新于2025-09-04 15:30:14