Deterministic Orientation Control of Ferroelectric HfO2 Thin Film Growth by a Topotactic Phase Transition of an Oxide Electrode.

The scale-free ferroelectricity with superior Si compatibility of HfO2 has reawakened the feasibility of scaled-down nonvolatile devices and beyond the complementary metal-oxide-semiconductor (CMOS) architecture based on ferroelectric materials. However, despite the rapid development, fundamental understanding, and control of the metastable ferroelectric phase in terms of oxygen ion movement of HfO2 remain ambiguous. In this study, we have deterministically controlled the orientation of a single-crystalline ferroelectric phase HfO2 thin film via oxygen ion movement. We induced a topotactic phase transition of the metal electrode accompanied by the stabilization of the differently oriented ferroelectric phase HfO2 through the migration of oxygen ions between the oxygen-reactive metal electrode and the HfO2 layer. By stabilizing different polarization directions of HfO2 through oxygen ion migration, we can gain a profound understanding of the oxygen ion-relevant unclear phenomena of ferroelectric HfO2.

Synthesis and characterization of SiC nanocomposite catalyst supports with self-formed nanowires.

Nickel-loaded SiC-alumina structural catalysts containing nanowires were facilely fabricated via modified sol-gel process mediated by supercritical carbon dioxide, followed by thermal-treatment. The nanowires were formed by metal-catalyzed growth on the outer and inner parts of SiC-alumina nanocomposite beads containing more than 3 wt.% of the metal seed at a moderate temperature of 1,100 degrees C under nitrogen gas flow. Highly dispersed Ni active catalysts were deposited on the surface of the nanowires formed outer and inner parts of the bead catalyst supports through the catalyst pretreatment process in the supercritical carbon dioxide. As a result, a new Ni/SiC heterogeneous catalyst with an enhanced surface area was successfully prepared using the SiC-alumina catalyst supports with a nanowire structure.

Retinal nerve fiber layer measurement variability with spectral domain optical coherence tomography.

PURPOSE: To evaluate the effect of the scanning laser ophthalmoscope (SLO) guided re-test mode on short- and long-term measurement variability of peripapillary retinal nerve fiber layer (RNFL) thickness obtained by spectral domain-SLO optical coherence tomography (SD-SLO/OCT). METHODS: Seventy five healthy eyes were scanned 3 times per day (intra-session variability) by both the SLO guided re-test mode and the independent mode of SD-SLO/OCT. Subjects were scanned 3 times by both modes at visits within a 2-week interval (inter-session variability). For testing longitudinal variability, 3 separate exams were performed over 6 months by both modes. The coefficient of variation (CV), reproducibility coefficient (RC) and intraclass correlation coefficient of RNFL thickness were compared between the two modes. RESULTS: The intra-session RC and CV ranged from 5.4 to 12.9 microns and 1.76% to 5.72% when measured by independent mode and 5.4 to 12.5 microns and 1.75% to 5.58% by re-test mode, respectively. The inter-session RC and CV ranged from 5.8 to 13.3 microns and 1.89% to 5.78% by independent mode and 5.8 to 12.7 microns and 1.90% to 5.54% by re-test mode, respectively. Intra-session and inter-session variability measurements were not significantly different between the two modes. The longitudinal RC and CV ranged from 8.5 to 19.2 microns and 2.79% to 7.08% by independent mode and 7.5 to 14.4 microns and 2.33% to 6.22% by re-test mode, respectively. Longitudinal measurement variability was significantly lower when measured by the re-test mode compared to the independent mode (average, p = 0.011). CONCLUSIONS: The SLO guided re-test mode for RNFL thickness measurement in SD-SLO/OCT employing a tracking system improved long-term reproducibility by reducing variability induced by inconsistent scan circle placement.

Progression detection in different stages of glaucoma: mean deviation versus visual field index.

PURPOSE: We evaluated and compared visual field index (VFI) and mean deviation (MD) capacity in detecting glaucoma progression at different stages. METHODS: Participants were classified as having early-, moderate-, or advanced-stage glaucoma. Trend-based approaches (TA) using linear regression analysis of the VFI and MD (VFI TA, MD TA) over patient age were performed. The rate was determined by both approaches at different stages of glaucoma. RESULTS: We analyzed 173 eyes of 173 participants (mean follow-up 6.2 years). Glaucoma progressed in 24 eyes (13.9%) as determined by VFI TA and in 21 eyes (12.1%) as determined by MD TA. Agreement between VFI TA and MD TA was moderate to good (κ = 0.617). The rate was -0.29 ± 2.31 dB per year as determined by MD TA and 1.25 ± 4.79% per year as determined by VFI TA. Progression rate according to glaucoma severity was not significantly different among subgroups when assessed by both trend-based approaches. CONCLUSION: VFI TA and MD TA performed similarly in measuring different stages of glaucoma progression. However, VFI TA and MD TA did not have agree perfectly in glaucoma progression detection. As glaucomatous changes can be general or localized, we suggest that changes in the MD and VFI should be considered when monitoring glaucoma progression through all stages.

Comparison between deviation map algorithm and peripapillary retinal nerve fiber layer measurements using Cirrus HD-OCT in the detection of localized glaucomatous visual field defects.

PURPOSE: To compare the capability of the deviation map algorithm and peripapillary retinal nerve fiber layer (pRNFL) thickness measurements, both determined using Cirrus spectral domain optical coherence tomography (Carl Zeiss Meditec Inc., Dublin, CA), in discrimination between healthy and glaucomatous eyes. METHODS: This cross-sectional comparative prospective study included 54 patients with glaucoma with localized visual field (VF) defects confined to 1 hemifield and 54 normal controls. Mean pRNFL thickness corresponding to localized VF defect was calculated. A deviation Score (DS) was assigned by customized Image J software (Http://www.rsb.info.hih.gov/ij/18) calculating the number of abnormal superpixels in the deviation maps corresponding to localized VF defect. Correlations between DS and mean pRNFL thickness, and VF parameters were obtained. The areas under receiver operating characteristic curves of the DS and mean pRNFL thickness used for discriminating between controls and glaucomatous eyes were compared. RESULTS: DS and the average pRNFL thickness measurements showed a strong correlation (R, -0.844, P<0.0001). There were also significant correlations between DS, mean deviation (MD), and pattern standard deviation (R, -0.678, 0.699, respectively). The areas under receiver operating characteristic curves of the mean pRNFL thickness (0.892) and DS (0.958) differed significantly (P=0.0051). The sensitivities at 80%, 90%, and 95% specificities were 94.4%, 90.6%, and 88.6%, respectively, for DS and 74.5%, 58.8%, and 47.3%, for mean pRNFL thickness. CONCLUSIONS: The deviation map algorithm showed a superior capability for detection of localized glaucomatous VF defects when compared with traditional pRNFL thickness measurements. There were statistically significant correlations between the deviation map algorithm and VF indices.

Glaucoma progression detection by retinal nerve fiber layer measurement using scanning laser polarimetry: event and trend analysis.

PURPOSE: To evaluate the use of scanning laser polarimetry (SLP, GDx VCC) to measure the retinal nerve fiber layer (RNFL) thickness in order to evaluate the progression of glaucoma. METHODS: Test-retest measurement variability was determined in 47 glaucomatous eyes. One eye each from 152 glaucomatous patients with at least 4 years of follow-up was enrolled. Visual field (VF) loss progression was determined by both event analysis (EA, Humphrey guided progression analysis) and trend analysis (TA, linear regression analysis of the visual field index). SLP progression was defined as a reduction of RNFL exceeding the predetermined repeatability coefficient in three consecutive exams, as compared to the baseline measure (EA). The slope of RNFL thickness change over time was determined by linear regression analysis (TA). RESULTS: Twenty-two eyes (14.5%) progressed according to the VF EA, 16 (10.5%) by VF TA, 37 (24.3%) by SLP EA and 19 (12.5%) by SLP TA. Agreement between VF and SLP progression was poor in both EA and TA (VF EA vs. SLP EA, k = 0.110; VF TA vs. SLP TA, k = 0.129). The mean (±standard deviation) progression rate of RNFL thickness as measured by SLP TA did not significantly differ between VF EA progressors and non-progressors (-0.224 ± 0.148 µm/yr vs. -0.218 ± 0.151 µm/yr, p = 0.874). SLP TA and EA showed similar levels of sensitivity when VF progression was considered as the reference standard. CONCLUSIONS: RNFL thickness as measurement by SLP was shown to be capable of detecting glaucoma progression. Both EA and TA of SLP showed poor agreement with VF outcomes in detecting glaucoma progression.

Mesencephalic midline change on transcranial sonography in early Parkinson's disease patients with depression.

Recently, several studies using transcranial sonography (TCS) have resulted in the alteration of the mesencephalic midline in patients with depression. We aimed to investigate and compare sonographic abnormalities in the brainstem raphe (BR) in patients with Parkinson's disease (PD) and controls, according to presence of depression. Study participants totaled 61 patients with PD (29 PD without depression, 32 PD with depression) and 41 controls. Results indicated that decreased BR echogenicity was much higher in PD patients with depression (PD+D) than in those without depression (PD-D). Of the 61 PD patients, 32 (52.4%) had depression as diagnosed by psychiatric assessment, and 13 (17.6%) were excluded, due to insufficient temporal windows. Based on these results, the use of TCS with respect to the mesencephalic midline may be useful in detecting depression, a risk factor for the development of PD.

Characteristics of visual field progression in medically treated normal-tension glaucoma patients with unstable ocular perfusion pressure.

PURPOSE: To investigate the characteristics of visual field (VF) progression in medically treated normal-tension glaucoma (NTG) patients (Koreans) with unstable ocular perfusion pressure (OPP). METHODS: One hundred one eyes of 101 NTG patients followed up for more than 4 years (mean follow-up, 6.2 years ± 12.1 months) were included. Modified Anderson criteria (MC) and linear regression analysis (LA) of VF mean deviation (MD) within the central 10° and 10° to 24° area were assessed for determining VF progression in groups with lowest (LMF) and highest (HMF) 24-hour mean OPP [MOPP = 2/3;(mean arterial pressure - IOP)] fluctuation. Kaplan-Meier analyses were used to compare the elapsed time of confirmed VF progression in the two groups. Hazard ratios (HRs) for the association between clinical risk factors including 24-hour MOPP and central VF progression were obtained by using Cox proportional hazards models. RESULTS: Three of 33 eyes in the LMF progressed, whereas 12 of 34 eyes in the HMF progressed within the central 10° according to the MC; the between-group difference was significant (P = 0.010). By LA within the central 10°, two eyes from the LMF and nine from the HMF groups showed progression (P = 0.025). The HMF showed a greater cumulative probability of central VF progression than the LMF, by both LA and MC (Kaplan-Meier analysis, P = 0.003, 0.015, log-rank test). In multivariate analysis, only 24-hour MOPP fluctuation was significantly associated with central VF progression (P = 0.014). CONCLUSIONS: The 24-hour MOPP fluctuation was the most consistent prognostic factor among various IOP, blood pressure, and clinical factors for central VF glaucomatous progression in our series of NTG eyes.

Detection of glaucoma by spectral domain-scanning laser ophthalmoscopy/optical coherence tomography (SD-SLO/OCT) and time domain optical coherence tomography.

PURPOSE: To evaluate the relationship between time-domain and spectral domain-scanning laser ophthalmoscopy/optical coherence tomography (SD-SLO/OCT), and to compare the ability of these methods to detect glaucoma. METHODS: Forty-nine glaucoma and 43 healthy participants were imaged by SD-SLO/OCT and Stratus OCT. Bland-Altman plots were used to compare the measurements of retinal nerve fiber layer (RNFL) thickness. Areas under the receiver operating characteristics curves (AUCs), including the average thickness, thickness in each of the 4 quadrants, and thickness at each of the 12 clock-hours were compared. Sensitivity and specificity of normative classification of the 2 OCTs for detection of glaucoma were calculated. RESULTS: The Bland-Altman plot showed good agreement between the 2 instruments. In eyes with glaucoma, RNFL thickness was greater when measured by SD-SLO/OCT than Stratus OCT in most sectors of the eye (Average RNFL thickness: SD-SLO/OCT, 82.7±15.3 µm; Stratus OCT, 76.9±18.4 µm; P<0.001). However, the differences between 2 OCTs were not significant in healthy participants. The AUCs of average RNFL measurements for discrimination of glaucoma did not differ significantly between the instruments (SD-SLO/OCT, 0.969; Stratus OCT, 0.959; P=0.535). SD-SLO/OCT showed similar sensitivity (57.1%) with Stratus OCT (53.4%) for detection of glaucoma in normative classification of average RNFL thickness. CONCLUSIONS: Both OCT technologies did well in the diagnosis of glaucoma. Although there were small differences in the 2 instruments in measured RNFL thickness of glaucomatous eyes, in general there was good agreement between the 2 OCTs. SD-SLO/OCT classified more glaucomatous eyes as abnormal based on its normative database.

Residual anterior chamber angle closure in narrow-angle eyes following laser peripheral iridotomy: anterior segment optical coherence tomography quantitative study.

PURPOSE: To study quantitative changes in anterior chamber angle (ACA) after laser peripheral iridotomy (LPI) in narrow-angle eyes using anterior segment optical coherence tomography (AS-OCT). METHODS: Eighteen subjects with narrow angles were imaged with AS-OCT for determining test-retest variability. Forty-six participants with narrow angles were scanned with AS-OCT before LPI and 4 weeks after LPI. The presence of ACA closure by both AS-OCT imaging and gonioscopy was compared before and after LPI. Three ACA parameters by AS-OCT, angle opening distance at 500 µm (AOD(500)), trabecular-ris space area at 500 µm (TISA(500)) and angle recess area at 500 µm (ARA(500)), at both nasal and temporal quadrants were incorporated for analysis. The increment of ACA parameters defined as exceeding the 95% confidence interval of test-retest variability was assessed after LPI. RESULTS: All 3 parameters obtained from the 18 eyes showed good measurement reproducibility (intraclass correlation coefficient 0.850-0.979). Persistent angle closure was detected in 23.9% of eyes by gonioscopy, and in 34.8% of eyes by AS-OCT images at temporal quadrant after LPI. When assessed by measurement variability criteria, the percentage of eyes that showed no significant change in ACA parameters ranged from 23.9% to 45.7% after LPI. CONCLUSIONS: Overall, ACA parameters changed significantly after LPI; however, when assessed by AS-OCT, ACA remained unchanged in some narrow-angle eyes despite LPI. Our findings suggest that multiple causes other than pupillary block may contribute to narrow-angle closure following LPI.

Spectral-domain optical coherence tomography and scanning laser polarimetry in glaucoma diagnosis.

PURPOSE: To evaluate glaucoma diagnostic capability of the retinal nerve fiber layer (RNFL) imaging by spectral-domain optical coherence tomography (Cirrus OCT) and scanning laser polarimetry (GDx VCC). METHODS: We imaged 88 glaucomatous and 77 healthy eyes using both devices. Areas under the receiver-operating characteristic curves (area under the curves, AUCs) and sensitivities at fixed specificities of average, superior, and inferior RNFL thickness were compared. Likelihood ratios (LRs) and diagnostic agreement based on normative classifications yielded by both devices were determined. RESULTS: The best performing parameter was the nerve fiber indicator (NFI) in GDx VCC and inferior RNFL thickness in Cirrus OCT (AUC = 0.912, 0.961, P = 0.045). The AUCs of the Cirrus OCT were significantly higher than those of GDx VCC in all parameters. Most of the parameters in Cirrus OCT were more sensitive than GDx VCC in the detection of glaucoma at fixed specificity values. Cirrus OCT had an infinite LR with abnormal classification results in both average and superior RNFL thickness. There was good agreement between the two instruments with respect to abnormal classifications (kappa, 0.611-0.766) CONCLUSION: Both Cirrus OCT and GDx VCC RNFL measurements showed good glaucoma diagnostic capabilities. Cirrus OCT showed higher sensitivities than GDx VCC.

Effect of age on anterior chamber angle configuration in Asians determined by anterior segment optical coherence tomography; clinic-based study.

PURPOSE: To evaluate the distribution of anterior chamber angle (ACA) parameters and to assess association of these parameters with age in Asian subjects. METHODS: Four hundred and thirty-nine consecutive Korean subjects aged from 30 to 89 were enrolled from a university clinic. All participants were scanned using anterior segment optical coherence tomography (AS-OCT, Visante, version 2.0). We measured ACA parameters such as anterior chamber depth (ACD), angle opening distance at 500 and 750µm (AOD(500,750) ), angle recess area at 500 and 750µm (ARA(500,750) ), trabecular iris space area at 500 and 750µm (TISA(500,750) ), and determined age-related changes in these parameters with use of a linear mixed effect model that adjusted for gender, axial length, intraocular pressure, and keratometry data. Slopes of ACA parameters as a function of age were determined. For various AS-OCT parameters, the normalized slope was calculated by dividing the slope by the mean value. RESULTS: All analysed ACA parameters decreased with age in both nasal and temporal quadrants. Axial length and keratometry data were significant covariates for ACA changes. The slopes of ACD were -0.02396mm/year, AOD(500) , ARA(500) , and TISA(500) measured at the temporal angle were -0.00634mm/year, -0.0019mm(2) /year, and -0.00177mm(2) /year, respectively. There was no age-dependent difference in central corneal thickness (p value; 0.4597) Based on the normalized slopes, the AOD showed the steepest slope at both temporal and nasal sectors. CONCLUSION: All ACA parameters assessed by AS-OCT, which accounted for other ocular biometric parameters, showed significant negative slopes with increasing age. These results should be considered when assessing changes in the anterior chamber over time.

Relationship between visual field sensitivity and macular ganglion cell complex thickness as measured by spectral-domain optical coherence tomography.

PURPOSE: To evaluate the strength and pattern of the relationship between visual field (VF) mean sensitivity (MS), assessed by standard automated perimetry (SAP), and macular ganglion cell complex thickness (GCCT), measured with spectral-domain optical coherence tomography (SD-OCT). METHODS: Ninety-seven glaucoma patients were enrolled. GCCT, determined by ganglion cell complex (GCC) scanning, and two peripapillary retinal nerve fiber layer thickness (pRNFLT) measurements, using the NHM4 (RNFL1) and RNFL 3.45 (RNFL2) modes, were recorded. MS was recorded on the decibel (dB) and 1/L scales. The relationship between function (MS) and structure (GCC, pRNFLT) was sought. RESULTS: The association of MS (in decibels) with GCC global (r = 0.445) and sectoral (superior, r = 0.528; inferior, r = 0.370) thicknesses was not significantly different from that of MS to global (RNFL1, r = 0.505; RNFL2, r = 0.498) and sectoral (RNFL 1 superior, r = 0.559; inferior, r = 0.440; RNFL 2 superior, r = 0.535; inferior, r = 0.443) pRNFLT, on linear regression analysis. The relationship pattern was curvilinear on the dB scale against GCCT and RNFLT. Logarithmic regression of MS (using both the dB and 1/L scales) against GCCT and RNFLT was better than linear regression in describing the pattern of association. CONCLUSIONS: GCCT, determined by SD-OCT, showed correlation to MS of a strength similar to that demonstrated between MS and pRNFLT.

Macular and peripapillary retinal nerve fiber layer measurements by spectral domain optical coherence tomography in normal-tension glaucoma.

PURPOSE: To evaluate and compare the glaucoma discrimination ability of macular inner retinal layer (MIRL) thickness with that of peripapillary retinal nerve fiber layer (pRNFL) thickness measured by spectral-domain optical coherence tomography (RTVue-100; Optovue Inc, Fremont, CA) in patients with normal-tension glaucoma (NTG). METHODS: Sixty-five healthy subjects and 102 with NTG were enrolled. MIRL thickness provided by a ganglion cell complex (GCC) scan and two RNFL thicknesses measured by the NHM4 (RNFL1) and RNFL 3.45 (RNFL2) modes of the RTVue-100 system were analyzed. The areas under the receiver operating characteristic curves (AUCs) of MIRL and pRNFL thicknesses for discriminating patients with NTG from control subjects were determined. The AUCs were compared between patients with central visual field (VF) defects (VF; 10 degrees from fixation). RESULTS: The average MIRL thickness showed a strong correlation with both RNFL1 and -2 thicknesses (R(2) = 0.773, 0.774, both P < 0.0001). The AUCs for average MIRL, RNFL1, and RNFL2 thicknesses were not significantly different at 0.945, 0.973, and 0.976, respectively. However, the AUCs of the average and superior MIRL thicknesses were significantly less than that of the pRNFL thickness in eyes with moderate-to-advanced glaucoma and eyes with peripheral VF defects. CONCLUSIONS: The average MIRL thickness showed a strong correlation with pRNFL thickness, because patients with NTG at an early stage showed paracentral VF defects near the fixation point. MIRL thickness showed glaucoma discrimination ability comparable to that of pRNFL thickness in patients with NTG with early VF defects. In eyes with advanced or peripheral VF defect, pRNFL measurement showed a better glaucoma diagnostic ability than did MIRL measurement.

Comparison of retinal nerve fibre layer thickness measurements calculated by the optic nerve head map (NHM4) and RNFL3.45 modes of spectral-domain optical coherence tomography (RTVue-100).

AIM: To evaluate and compare retinal nerve fibre layer (RNFL) thickness measured by direct scanning (RNFL3.45 mode) and re-sampling from datasets (NHM4 mode) of RTVue-100 optical coherence tomography (OCT). METHODS: Thirty-six healthy subjects and 76 subjects with glaucoma were imaged with Stratus OCT (fast RNFL mode, RNFL3) and RTVue-100 OCT (NHM4 (RNFL1) and RNFL3.45 (RNFL2) modes). Measurement reproducibility was assessed in NHM4 and RNFL3.45 modes of RTVue-100 OCT (intraclass correlation coefficient (ICC)). Agreement between different RNFL measurements was analysed by Bland-Altman plot. The areas under the receiver operating characteristic (ROC) curves (AUCs) for discrimination between healthy and glaucoma were compared between the different RNFL measurements. RESULTS: Both NHM4 and RNFL3.45 modes showed excellent measurement reproducibilities (ICC 0.831-0.978). RNFL thicknesses by two different modes of the RTVue-100 OCT, and by the Stratus OCT, were correlated in all sectors, including average. There was no significant difference between RNFL1 and RNFL2 data. However, RNFL thickness in glaucomatous eyes by the RTVue-100 OCT was significantly greater than that measured by Stratus OCT. RNFL thicknesses determined by the two different modes of RTVue-100 OCT were in excellent agreement (95% limits of agreement -6.53 to 6.95 mum). All three RNFL measurements showed good glaucoma discrimination ability (AUC = RNFL1 0.970, RNFL2 0.962, RNFL3 0.971). CONCLUSIONS: RNFL thickness determined by direct scanning and re-sampling from datasets of RTVue-100 OCT were in good agreement. However, both measurements in glaucomatous subjects were significantly different from those with the Stratus OCT. Those findings should be considered when a patient is followed-up using different types of OCT.

Twenty-four hour ocular perfusion pressure fluctuation and risk of normal-tension glaucoma progression.

PURPOSE: To investigate the relationship between clinical factors including 24-hour mean ocular perfusion pressure (MOPP, (2/3) x mean arterial pressure [MAP] - intraocular pressure [IOP]) and visual field (VF) progression in eyes with medically treated normal-tension glaucoma (NTG). METHODS: One hundred one eyes of 101 NTG patients followed up for more than 4 years (mean follow-up, 6.2 years +/- 12.1 months) were included after retrospective chart review. Several clinical factors including demographic, systemic, ocular risk factors, and 24-hour MOPP were explored for associations with decreasing VF. Kaplan-Meier analyses were performed to compare outcomes with reference to four risk factors (age, myopia, and elevated MAP and MOPP fluctuation) for VF deterioration. Hazard ratios (HRs) for the association between potential risk factors and glaucoma progression were obtained using Cox proportional hazards models. RESULTS: Overall VF progression was detected in 29 (28.7%) eyes. There were significant differences between progressors and nonprogressors in nocturnal MAP and MOPP fluctuations (both P < 0.0001), 24-hour MAP, and MOPP fluctuations (both P < 0.0001), initial mean deviation (P = 0.0034), and pattern standard deviation (PSD) score (P < 0.0001). Both elevated 24-hour MAP and MOPP fluctuations were associated with greater VF progression probabilities based on Kaplan-Meier analyses. Among all risk factors investigated, the Cox proportional hazards model indicated that VF progression was significantly associated with 24-hour MOPP fluctuation and initial PSD score. CONCLUSIONS: Clinical factors other than IOP were associated with VF progression in our series of medically treated NTG eyes. Twenty-four-hour MOPP fluctuation was the most consistent prognostic factor for glaucoma progression.