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George L Spaeth - One of the best experts on this subject based on the ideXlab platform.
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disc damage Likelihood Scale ddls as a clinical indicator of the presence of a relative afferent pupillary defect rapd
Journal of Glaucoma, 2016Co-Authors: Alice Y. Zhang, Lan Lu, Nont Rutnin, Bruno Faria, Huseyin Guzel, Liang Liang, Patricia Martinez, Mike Tawfik, George L SpaethAbstract:PURPOSE:To evaluate clinical parameters and their relationship to the presence of a relative afferent pupillary defect (RAPD). MATERIALS AND METHODS:Retrospective chart review of 672 consecutive patients who presented to the Glaucoma Service at Wills Eye Hospital from January 1 through May 29, 2012. Swinging flashlight method (SFM) was used to test for RAPDs. Records of visual acuity, intraocular pressure (IOP), disc-damage Likelihood Scale (DDLS), cup/disc (C/D) ratio, visual field mean deviation (MD), optical coherence tomography (OCT), and Heidelberg retinal tomography (HRT) asymmetries were examined. We measured the prevalence of RAPDs as clinical asymmetries increase, calculated cut-off points for clinical asymmetries that optimized sensitivity and specificity in detecting RAPDs, and determined values of clinical asymmetries above which a RAPD always exists. RESULTS:Upon exclusion, we studied 409 patients, 175 (42.8%) with RAPDs and 234 (57.2%) without. Age, visual acuity, IOP, DDLS, C/D ratio, MD, retina nerve fiber layer thickness by OCT, HRT C/D, and HRT rim area asymmetries all correlated with RAPD status (OCT and HRT parameters did not include enough patients for multivariable analysis or cut-off determination). Multivariable analysis indicated that IOP, DDLS, and MD asymmetries were significantly correlated with RAPD status (P-value<0.05). Although the optimal cut-off values for the variables retained in the final multivariable model had low sensitivity and moderate specificity, DDLS had the highest specificity of 0.86. CONCLUSIONS:IOP, DDLS, and MD asymmetries had the best correlation with RAPD status, and increased asymmetries in these parameters were associated with higher Likelihood of RAPDs. DDLS score had the highest specificity in predicting a RAPD, and DDLS asymmetry scores ≥6 identified all cases of RAPDs.
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Evaluation of Nonmydriatic Hand-held Optic Disc Photography Grading in the Philadelphia Glaucoma Detection and Treatment Project.
Journal of Glaucoma, 2016Co-Authors: Michael Waisbourd, George L Spaeth, Jonathan S Myers, Bond Ea, Timothy Sullivan, Wanda Deborah Hu, Sonya B. Shah, Jeanne Molineaux, Harjeet Sembhi, Lisa A HarkAbstract:To determine the reproducibility of optic disc photograph grading obtained by a hand-held fundus camera and to determine the diagnostic value of these photographs in detecting patients with glaucoma in a community-based glaucoma-detection program.Patients underwent slit-lamp examination by an ophthalmologist who graded each patient's optic discs using 2 methods: cup-to-disc ratio (CDR) and disc damage Likelihood Scale (DDLS). After a comprehensive glaucoma evaluation, patients were diagnosed as having "glaucoma," "glaucoma suspect," or "no glaucoma." Nonmydriatic, monoscopic optic disc photographs were then taken with a portable digital imaging device. On a different day, the same examiner and a second observer graded the disc photographs in a masked manner and determined a diagnostic impression based only on the disc photographs.Of the 1649 patients examined, 119 subjects were randomly selected according to 3 groups of diagnoses: "glaucoma" (n=36), "glaucoma suspect" (n=50), and "no glaucoma" (n=33). For CDR, the intraobserver agreement was 0.71 and the interobserver agreement was 0.69. For disc DDLS, the intraobserver agreement was 0.65 and the interobserver agreement was 0.67. The area under the receiver-operating characteristic distinguishing between normal and glaucoma was 0.88 and 0.86 for CDR and disc DDLS, respectively.Nonmydriatic, monoscopic disc photographs obtained by a hand-held camera had only moderate disc grading reproducibility. This could be due to a reduced quality of images, making interpretation more challenging, due to taking photographs through small pupils by a hand-held camera and the high percentage of patients with significant cataracts.
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Disc-damage Likelihood Scale (DDLS) as a Clinical Indicator of the Presence of a Relative Afferent Pupillary Defect (RAPD).
Journal of Glaucoma, 2016Co-Authors: Alice Y. Zhang, Lan Lu, Nont Rutnin, Bruno Faria, Huseyin Guzel, Liang Liang, Patricia Martinez, Mike Tawfik, George L SpaethAbstract:PURPOSE:To evaluate clinical parameters and their relationship to the presence of a relative afferent pupillary defect (RAPD). MATERIALS AND METHODS:Retrospective chart review of 672 consecutive patients who presented to the Glaucoma Service at Wills Eye Hospital from January 1 through May 29, 2012. Swinging flashlight method (SFM) was used to test for RAPDs. Records of visual acuity, intraocular pressure (IOP), disc-damage Likelihood Scale (DDLS), cup/disc (C/D) ratio, visual field mean deviation (MD), optical coherence tomography (OCT), and Heidelberg retinal tomography (HRT) asymmetries were examined. We measured the prevalence of RAPDs as clinical asymmetries increase, calculated cut-off points for clinical asymmetries that optimized sensitivity and specificity in detecting RAPDs, and determined values of clinical asymmetries above which a RAPD always exists. RESULTS:Upon exclusion, we studied 409 patients, 175 (42.8%) with RAPDs and 234 (57.2%) without. Age, visual acuity, IOP, DDLS, C/D ratio, MD, retina nerve fiber layer thickness by OCT, HRT C/D, and HRT rim area asymmetries all correlated with RAPD status (OCT and HRT parameters did not include enough patients for multivariable analysis or cut-off determination). Multivariable analysis indicated that IOP, DDLS, and MD asymmetries were significantly correlated with RAPD status (P-value
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Relationships Between Measures of the Ability to Perform Vision-Related Activities, Vision-Related Quality of Life, and Clinical Findings in Patients With Glaucoma
JAMA Ophthalmology, 2015Co-Authors: Feyzahan Ekici, Patricia Martinez, Sheryl S. Wizov, Michael Waisbourd, Natasha V Nayak, Sarah E. Hegarty, Lisa A Hark, George L SpaethAbstract:Importance To our knowledge, few studies have combined an objective measure of vision-related performance (VRP) and subjective measures of vision-related quality of life (VRQoL) with clinically related visual parameters, particularly in a large, prospective, cohort study setting. Objective To examine the relationships between clinical visual assessments and both a VRP and 2 self-reported VRQoL measurements. Design, Setting, and Participants Patients (N = 161) with moderate-stage glaucoma recruited from the Glaucoma Service at Wills Eye Hospital, Philadelphia, Pennsylvania, were enrolled from May 2012 to May 2014 in an ongoing prospective, 4-year longitudinal observational study. This report includes cross-sectional results from the baseline visit. Patients received a complete ocular examination, automated visual field (VF) test and Cirrus optical coherence tomographic scan. Contrast sensitivity was measured with the Pelli-Robson and the Spaeth-Richman Contrast Sensitivity (SPARCS) tests. Vision-related performance was assessed by the Compressed Assessment of Ability Related to Vision (CAARV) test. Vision-related QoL was assessed by the National Eye Institute Visual Function Questionnaire 25 (NEI-VFQ-25) and a modified Glaucoma Symptom Scale (MGSS). Main Outcomes and Measures Correlations between clinical measures and CAARV, NEI-VFQ-25, and MGSS scores. Results A total of 161 patients were enrolled in the study. The strongest correlation was found between SPARCS score in the better eye and total CAARV score ( r = 0.398; 95% CI, 0.235-0.537; P r = 0.353; 95% CI, 0.186-0.499; P = .001), VF mean deviation ( r = 0.366; 95% CI, 0.200-0.510; P r = −0.326, 95% CI = −0.476 to −0.157; P = .003) in the better eye. There were more statistically significant correlations between contrast sensitivity tests and VF mean deviation with VRQoL measurements than with other clinical measures (visual acuity, intraocular pressure, Disc Damage Likelihood Scale, and mean retinal nerve fiber layer thickness). The MGSS scores were lower (worse) in women compared with men ( P = .03 for binocular, P = .01 for better eye, and P = .05 for the worse eye). Structural measures (eg, Disc Damage Likelihood Scale, and retinal nerve fiber layer thickness) were generally not informative with respect to VRP or VRQoL. Conclusions and Relevance Contrast sensitivity tests and VF mean deviation were associated with both objective measures of the ability to act and subjective measurements of VRQoL. The strongest correlation was between SPARCS score (contrast sensitivity) in the better eye and total CAARV score. Therefore, measurement of contrast sensitivity should be considered when evaluating patients’ VRQoL. The results of this study were limited by the patient population and apply only within the bounds of the tested cohort.
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SPARCS: a new method of evaluating contrast sensitivity in patients with glaucoma
Acta Ophthalmologica, 2012Co-Authors: George L Spaeth, J RichmanAbstract:Purpose To evaluate a new contrast sensitivity instrument as a diagnostic test for glaucoma. Methods Glaucoma patients, glaucoma suspects, and controls were prospectively evaluated using the Spaeth-Richman Contrast Sensitivity (SPARCS) method. Testing was performed monocularly in a standardized testing environment. Contrast thresholds for the central, superonasal, superotemporal, inferonasal, and inferotemporal areas of vision were determined. The contrast sensitivity scores for each area of vision and the cumulative scores were then compared to subjects’ visual field and the amount of optic nerve damage, measured by the Disc Damage Likelihood Scale (DDLS) and the vertical cup to disc ratio. The results were analyzed with Spearman coefficients for continuous variables and the Kruskal-Wallis test for categorical variables. Results One hundred and eighteen patients with glaucoma, 18 glaucoma suspects, and 125 controls completed the study. The mean SPARCS scores were 63.0 for patients with glaucoma, 71.9 for glaucoma suspects, and 77.1 for controls (p < 0.01). SPARCS had strong correlations with patients’ visual field (r = 0.76, p < 0.01), DDLS (r = -0.73, p < 0.01), and vertical cup to disc (r = -0.64, p < 0.01). Conclusion SPARCS was able to discriminate well between patients with glaucoma, glaucoma suspects, and controls. SPARCS had strong relationships with the degree of visual field and optic nerve damage. SPARCS may become a standard technique to assess visual ability in glaucoma patients. Commercial interest
Toru Nakazawa - One of the best experts on this subject based on the ideXlab platform.
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estimation of the disc damage Likelihood Scale in primary open angle glaucoma the glaucoma stereo analysis study
Graefes Archive for Clinical and Experimental Ophthalmology, 2016Co-Authors: Yasushi Kitaoka, Masaki Tanito, Yu Yokoyama, Koji Nitta, Maki Katai, Kazuko Omodaka, Toru NakazawaAbstract:Purpose The Glaucoma Stereo Analysis Study (GSAS), a cross-sectional multicenter collaborative study, used a stereo fundus camera (nonmyd WX) to assess various morphological parameters of the optic nerve head (ONH) in glaucoma patients. We examined the associations between the Disc Damage Likelihood Scale (DDLS), a grading system for estimating glaucomatous ONH damage, and each parameter.
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Estimation of the Disc Damage Likelihood Scale in primary open-angle glaucoma: the Glaucoma Stereo Analysis Study
Graefe's Archive for Clinical and Experimental Ophthalmology, 2016Co-Authors: Yasushi Kitaoka, Masaki Tanito, Yu Yokoyama, Koji Nitta, Maki Katai, Kazuko Omodaka, Toru NakazawaAbstract:Purpose The Glaucoma Stereo Analysis Study (GSAS), a cross-sectional multicenter collaborative study, used a stereo fundus camera (nonmyd WX) to assess various morphological parameters of the optic nerve head (ONH) in glaucoma patients. We examined the associations between the Disc Damage Likelihood Scale (DDLS), a grading system for estimating glaucomatous ONH damage, and each parameter. Methods The study included 187 eyes of 187 patients with primary open-angle glaucoma or normal-tension glaucoma. ONH morphological parameters including the DDLS stage were calculated with prototype analysis software. Three independent graders classified each optic disc appearance into four different types: focal ischemic, myopic glaucomatous, senile sclerotic, and generalized enlargement. The correlations between the DDLS and patient characteristics or each ONH parameter were analyzed with Spearman’s rank correlation coefficient. Results The DDLS was correlated positively with baseline intraocular pressure and visual field pattern standard deviation, and negatively with visual field mean deviation. The DDLS was strongly correlated with vertical cup-to-disc ratio and horizontal cup-to-disc ratio positively, and with minimum rim-disc ratio negatively. The mean DDLS stage in the myopic glaucomatous type tended to be higher than the scores in other types. Conclusion The DDLS obtained through three-dimensional ONH analysis correlates well with the severity of glaucomatous ONH and visual field damage.
Lianwen Jin - One of the best experts on this subject based on the ideXlab platform.
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A Pointing Gesture Based Egocentric Interaction System: Dataset, Approach and Application
IEEE Computer Society Conference on Computer Vision and Pattern Recognition Workshops, 2016Co-Authors: Yichao Huang, Xiaorui Liu, Xin Zhang, Lianwen JinAbstract:With the heated trend of augmented reality (AR) and pop-ularity of smart head-mounted devices, the development of natural human device interaction is important, especially the hand gesture based interaction. This paper presents a solution for the point gesture based interaction in the ego-centric vision and its application. Firstly, a dataset named EgoFinger is established focusing on the pointing gesture for the egocentric vision. We discuss the dataset collec-tion detail and as well the comprehensive analysis of this dataset, including background and foreground color distri-bution, hand occurrence Likelihood, Scale and pointing an-gle distribution of hand and finger, and the manual labeling error analysis. The analysis shows that the dataset covers substantial data samples in various environments and dy-namic hand shapes. Furthermore, we propose a two-stage Faster R-CNN based hand detection and dual-target finger-tip detection framework. Comparing with state-of-art track-ing and detection algorithm, it performs the best in both hand and fingertip detection. With the large-Scale dataset, we achieve fingertip detection error at about 12.22 pixels in 640px × 480px video frame. Finally, using the fingertip detection result, we design and implement an input system for the egocentric vision, i.e., Ego-Air-Writing. By consid-ering the fingertip as a pen, the user with wearable glass can write character in the air and interact with system us-ing simple hand gestures.
Yichao Huang - One of the best experts on this subject based on the ideXlab platform.
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CVPR Workshops - A Pointing Gesture Based Egocentric Interaction System: Dataset, Approach and Application
2016 IEEE Conference on Computer Vision and Pattern Recognition Workshops (CVPRW), 2016Co-Authors: Yichao Huang, Xin ZhangAbstract:With the heated trend of augmented reality (AR) and popularity of smart head-mounted devices, the development of natural human device interaction is important, especially the hand gesture based interaction. This paper presents a solution for the point gesture based interaction in the egocentric vision and its application. Firstly, a dataset named EgoFinger is established focusing on the pointing gesture for the egocentric vision. We discuss the dataset collection detail and as well the comprehensive analysis of this dataset, including background and foreground color distribution, hand occurrence Likelihood, Scale and pointing angle distribution of hand and finger, and the manual labeling error analysis. The analysis shows that the dataset covers substantial data samples in various environments and dynamic hand shapes. Furthermore, we propose a two-stage Faster R-CNN based hand detection and dual-target fingertip detection framework. Comparing with state-of-art tracking and detection algorithm, it performs the best in both hand and fingertip detection. With the large-Scale dataset, we achieve fingertip detection error at about 12.22 pixels in 640px × 480px video frame. Finally, using the fingertip detection result, we design and implement an input system for the egocentric vision, i.e., Ego-Air-Writing. By considering the fingertip as a pen, the user with wearable glass can write character in the air and interact with system using simple hand gestures.
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A Pointing Gesture Based Egocentric Interaction System: Dataset, Approach and Application
IEEE Computer Society Conference on Computer Vision and Pattern Recognition Workshops, 2016Co-Authors: Yichao Huang, Xiaorui Liu, Xin Zhang, Lianwen JinAbstract:With the heated trend of augmented reality (AR) and pop-ularity of smart head-mounted devices, the development of natural human device interaction is important, especially the hand gesture based interaction. This paper presents a solution for the point gesture based interaction in the ego-centric vision and its application. Firstly, a dataset named EgoFinger is established focusing on the pointing gesture for the egocentric vision. We discuss the dataset collec-tion detail and as well the comprehensive analysis of this dataset, including background and foreground color distri-bution, hand occurrence Likelihood, Scale and pointing an-gle distribution of hand and finger, and the manual labeling error analysis. The analysis shows that the dataset covers substantial data samples in various environments and dy-namic hand shapes. Furthermore, we propose a two-stage Faster R-CNN based hand detection and dual-target finger-tip detection framework. Comparing with state-of-art track-ing and detection algorithm, it performs the best in both hand and fingertip detection. With the large-Scale dataset, we achieve fingertip detection error at about 12.22 pixels in 640px × 480px video frame. Finally, using the fingertip detection result, we design and implement an input system for the egocentric vision, i.e., Ego-Air-Writing. By consid-ering the fingertip as a pen, the user with wearable glass can write character in the air and interact with system us-ing simple hand gestures.
Gaetano Scarano - One of the best experts on this subject based on the ideXlab platform.
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fast maximum Likelihood Scale parameter estimation from histogram measurements
IEEE Signal Processing Letters, 2011Co-Authors: Stefania Colonnese, Stefano Rinauro, Gaetano ScaranoAbstract:In this letter, we address the problem of estimating a parameter acting as a Scale factor on the observations probability density function (pdf), i.e. a Scale parameter. Histogram based Maximum Likelihood (ML) estimation of a Scale parameter requires the evaluation of a discrete Scale correlation. We show how ML estimation can be implemented by means of a computationally efficient Discrete Fourier Transform based procedure, when geometric histogram sampling is adopted. As a case study, we analyze a gain estimator for general QAM constellations. Simulation results and theoretical performance analysis show that the presented ML estimator outperforms selected state of the art estimators, approaching the Cramer-Rao Lower Bound (CRLB) for a wide range of SNR.
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Fast Maximum Likelihood Scale Parameter Estimation From Histogram Measurements
IEEE Signal Processing Letters, 2011Co-Authors: Stefania Colonnese, Stefano Rinauro, Gaetano ScaranoAbstract:In this letter, we address the problem of estimating a parameter acting as a Scale factor on the observations probability density function (pdf), i.e. a Scale parameter. Histogram based Maximum Likelihood (ML) estimation of a Scale parameter requires the evaluation of a discrete Scale correlation. We show how ML estimation can be implemented by means of a computationally efficient Discrete Fourier Transform based procedure, when geometric histogram sampling is adopted. As a case study, we analyze a gain estimator for general QAM constellations. Simulation results and theoretical performance analysis show that the presented ML estimator outperforms selected state of the art estimators, approaching the Cramér-Rao Lower Bound (CRLB) for a wide range of SNR.
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EUSIPCO - Maximum Likelihood Scale parameter estimation: An application to gain estimation for QAM constellations
2010Co-Authors: Stefania Colonnese, Stefano Rinauro, Gaetano ScaranoAbstract:In this paper we address the problem of Scale parameter estimation, introducing a reduced complexity Maximum Likelihood (ML) estimation procedure. The estimator stems from the observation that, when the estimandum acts as a shift parameter on a multinomially distributed statistic, direct maximization of the Likelihood function can be conducted by an efficient DFT based procedure. A suitable exponential warping of the observation's domain is known to transform a Scale parameter problem into a shift estimation problem, thus allowing the afore mentioned reduced complexity ML estimation for shift parameter to be applied also in Scale parameter estimation problems. As a case study, we analyze a gain estimator for general QAM constellations. Simulation results and theoretical performance analysis show that the herein presented estimator outperforms selected state of the art high order moments estimator, approaching the Cramer-Rao Lower Bound (CRLB) for a wide range of SNR.
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Maximum Likelihood Scale parameter estimation: An application to gain estimation for QAM constellations
2010 18th European Signal Processing Conference, 2010Co-Authors: Stefania Colonnese, Stefano Rinauro, Gaetano ScaranoAbstract:In this paper we address the problem of Scale parameter estimation, introducing a reduced complexity Maximum Likelihood (ML) estimation procedure. The estimator stems from the observation that, when the estimandum acts as a shift parameter on a multinomially distributed statistic, direct maximization of the Likelihood function can be conducted by an efficient DFT based procedure. A suitable exponential warping of the observation's domain is known to transform a Scale parameter problem into a shift estimation problem, thus allowing the afore mentioned reduced complexity ML estimation for shift parameter to be applied also in Scale parameter estimation problems. As a case study, we analyze a gain estimator for general QAM constellations. Simulation results and theoretical performance analysis show that the herein presented estimator outperforms selected state of the art high order moments estimator, approaching the Cramér-Rao Lower Bound (CRLB) for a wide range of SNR.