The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Robert N. Weinreb - One of the best experts on this subject based on the ideXlab platform.
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Bar graph of the distribution of eyes with visible localized retinal nerve fiber layer (RNFL) defects on optic disc Stereophotography by clock-hour.
2016Co-Authors: Chunwei Zhang, Robert N. Weinreb, Christopher A. Girkin, Felipe A. Medeiros, Andrew J Tatham, Jeffrey M Liebmann, Ricardo Y. Abe, Na’ama Hammel, Akram Belghith, Linda M. ZangwillAbstract:Bar graph of the distribution of eyes with visible localized retinal nerve fiber layer (RNFL) defects on optic disc Stereophotography by clock-hour.
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estimated retinal ganglion cell counts in glaucomatous eyes with localized retinal nerve fiber layer defects
American Journal of Ophthalmology, 2013Co-Authors: Andrew J Tatham, Linda M. Zangwill, Robert N. Weinreb, Christopher A. Girkin, Jeffrey M Liebmann, Felipe A. MedeirosAbstract:Purpose To estimate retinal ganglion cell (RGC) losses associated with visible glaucomatous localized retinal nerve fiber layer (RNFL) defects. Design Observational cross-sectional study. Methods A multicenter study of 198 normal eyes (138 subjects) and 66 glaucomatous eyes (55 subjects) recruited from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. All eyes underwent standard automated perimetry (SAP), spectral-domain optical coherence tomography, and fundus Stereophotography within 6 months. Glaucomatous eyes were included if localized RNFL defects were detected by masked grading of stereophotographs. The number of RGCs in each sector of a structure-function map was estimated using a previously published model combining RGC estimates from SAP and spectral-domain optical coherence tomography. The estimated percentage loss of RGCs (combined structure-function index) was calculated. Results In glaucomatous eyes, there were 136 sectors with visible RNFL defects and 524 sectors without visible RNFL defects. The most common sectors with visible RNFL defects were inferior and inferotemporal sectors, followed by superior and supertemporal sectors. Eyes with visible RNFL defects had a mean estimated RGC count of 657 172 cells versus 968 883 cells in healthy eyes ( P P P Conclusions Although visible localized RNFL defects often are considered an early sign of glaucoma, this study indicates that they are likely to be associated with large neuronal losses.
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Determinants of agreement between the confocal scanning laser tomograph and standardized assessment of glaucomatous progression
Ophthalmology, 2010Co-Authors: Gianmarco Vizzeri, Pamela A. Sample, Robert N. Weinreb, Christopher Bowd, Madhusudhanan Balasubramanian, Felipe A. Medeiros, Linda M. ZangwillAbstract:Purpose To estimate the agreement of confocal scanning laser tomograph (CSLT), topographic change analysis (TCA) with assessment of stereophotographs, and standard automated perimetry (SAP) for detecting glaucomatous progression and to identify factors associated with agreement between methods. Design Observational cohort study. Participants We included 246 eyes of 167 glaucoma patients, glaucoma suspects, and ocular hypertensives. Methods We included CSLT series (n ≥4 tests; mean follow-up, 4 years), stereophotographs, and SAP results in the analysis. The number of progressors by guided progression analysis (GPA, "likely progression"), progressors by masked stereophotographs assessment and progressors by TCA as determined for 3 parameters related to the number of progressed superpixels within the disc margin was determined. Agreement between progression by each TCA parameter, stereophotographs and GPA was assessed using the Kappa test. Analysis of variance with post hoc analysis was applied to identify baseline factors including image quality (standard deviation of the mean topography), disc size and disease severity (pattern standard deviation [PSD] and cup area) associated with agreement/nonagreement between methods. Main Outcome Measures Agreement in assessing glaucomatous progression between the methods including factors associated with agreement/nonagreement between methods. Results Agreement between progression by TCA and progression by stereophotographs and/or GPA was generally poor regardless of the TCA parameter and specificity cutoffs applied. For the parameters with the strongest agreement, cluster size in disc (CSIZE disc ) and cluster area in disc (CAREA disc ), kappa values were 0.16 (63.9%, agreement on 134 nonprogressing eyes and 23 progressing eyes) and 0.15 (64.1%, agreement on 135 nonprogressing eyes and 22 progressing eyes) at 99% cutoff. Most of the factors evaluated were not significantly associated with agreement/nonagreement between methods (all P >0.07). However, SAP PSD was greater in the progressors by Stereophotography only group compared with the progressors by TCA only group (5.8±4.7 and 2.6±2.2, respectively [ P = 0.003] for CSIZE disc at 95% specificity and 5.4±4.6 and 2.5±2.3, respectively [ P = 0.002] for CAREA disc at 99% specificity). Conclusions Agreement for detection of longitudinal changes between TCA, Stereophotography, and SAP GPA is poor. Progressors by Stereophotography only tended to have more advanced disease at baseline than progressors by TCA only. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
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agreement for detecting glaucoma progression with the gdx guided progression analysis automated perimetry and optic disc photography
Ophthalmology, 2010Co-Authors: Linda M. Zangwill, Pamela A. Sample, Robert N. Weinreb, Gianmarco Vizzeri, Christopher Bowd, Felipe A. Medeiros, Luciana M Alencar, Remo SusannaAbstract:Purpose To evaluate the ability of the GDx Variable Corneal Compensation (VCC) Guided Progression Analysis (GPA) software for detecting glaucomatous progression. Design Observational cohort study. Participants The study included 453 eyes from 252 individuals followed for an average of 46±14 months as part of the Diagnostic Innovations in Glaucoma Study. At baseline, 29% of the eyes were classified as glaucomatous, 67% of the eyes were classified as suspects, and 5% of the eyes were classified as healthy. Methods Images were obtained annually with the GDx VCC and analyzed for progression using the Fast Mode of the GDx GPA software. Progression using conventional methods was determined by the GPA software for standard automated achromatic perimetry (SAP) and by masked assessment of optic disc stereophotographs by expert graders. Main Outcome Measures Sensitivity, specificity, and likelihood ratios (LRs) for detection of glaucoma progression using the GDx GPA were calculated with SAP and optic disc stereophotographs used as reference standards. Agreement among the different methods was reported using the AC 1 coefficient. Results Thirty-four of the 431 glaucoma and glaucoma suspect eyes (8%) showed progression by SAP or optic disc stereophotographs. The GDx GPA detected 17 of these eyes for a sensitivity of 50%. Fourteen eyes showed progression only by the GDx GPA with a specificity of 96%. Positive and negative LRs were 12.5 and 0.5, respectively. None of the healthy eyes showed progression by the GDx GPA, with a specificity of 100% in this group. Inter-method agreement (AC 1 coefficient and 95% confidence intervals) for non-progressing and progressing eyes was 0.96 (0.94–0.97) and 0.44 (0.28–0.61), respectively. Conclusions The GDx GPA detected glaucoma progression in a significant number of cases showing progression by conventional methods, with high specificity and high positive LRs. Estimates of the accuracy for detecting progression suggest that the GDx GPA could be used to complement clinical evaluation in the detection of longitudinal change in glaucoma. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
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the relationship between intraocular pressure and progressive retinal nerve fiber layer loss in glaucoma
Ophthalmology, 2009Co-Authors: Felipe A. Medeiros, Linda M. Zangwill, Pamela A. Sample, Luciana M Alencar, Robert N. WeinrebAbstract:Purpose To evaluate the relationship between intraocular pressure (IOP) and progressive retinal nerve fiber layer (RNFL) loss, as measured by scanning laser polarimetry with enhanced corneal compensation (GDx ECC), in a cohort of glaucoma patients and individuals suspected of having the disease followed over time. Design Observational cohort study. Participants The study included 344 eyes of 204 patients recruited from the Diagnostic Innovations in Glaucoma Study (DIGS). There were 98 eyes (28%) with a diagnosis of glaucoma and 246 (72%) were considered glaucoma suspects at baseline. Methods Images were obtained annually with the GDx ECC scanning laser polarimeter, along with stereophotographs and SAP. The study included a total of 1211 GDx ECC visits with an average of 3.5 visits per eye. Progression was determined by the Guided Progression Analysis software for SAP and by masked assessment of stereophotographs performed by expert graders. Main Outcome Measures Random coefficient models were used to evaluate the relationship between IOP and RNFL thickness measurements over time in progressors and nonprogressors. Models were adjusted for baseline diagnosis and central corneal thickness. Results For all 344 eyes, the overall rate of change for the GDx ECC average thickness at an average IOP of 17 mmHg was −0.25 μm per year ( P = 0.002). Each 1-mmHg higher IOP was associated with an additional loss of 0.05 μm per year of RNFL ( P = 0.001). Twenty-nine eyes (8%) showed progression on SAP and/or optic disc stereophotographs. These eyes had a significantly higher rate of RNFL change (−0.95μm/year) than nonprogressors (−0.17 μm/year; P = 0.001). For progressors, each 1-mmHg higher IOP was associated with an additional loss of 0.13 μm per year of RNFL. Conclusions Higher levels of IOP during follow-up were significantly related to higher rates of progressive RNFL loss detected by the GDx ECC. These findings suggest that the GDx ECC may be helpful in monitoring progression and estimating rates of change in patients with glaucoma or suspected of having the disease. Also, they may contribute to a better understanding of the relationship between IOP and structural deterioration in glaucoma. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
Linda M. Zangwill - One of the best experts on this subject based on the ideXlab platform.
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Bar graph of the distribution of eyes with visible localized retinal nerve fiber layer (RNFL) defects on optic disc Stereophotography by clock-hour.
2016Co-Authors: Chunwei Zhang, Robert N. Weinreb, Christopher A. Girkin, Felipe A. Medeiros, Andrew J Tatham, Jeffrey M Liebmann, Ricardo Y. Abe, Na’ama Hammel, Akram Belghith, Linda M. ZangwillAbstract:Bar graph of the distribution of eyes with visible localized retinal nerve fiber layer (RNFL) defects on optic disc Stereophotography by clock-hour.
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estimated retinal ganglion cell counts in glaucomatous eyes with localized retinal nerve fiber layer defects
American Journal of Ophthalmology, 2013Co-Authors: Andrew J Tatham, Linda M. Zangwill, Robert N. Weinreb, Christopher A. Girkin, Jeffrey M Liebmann, Felipe A. MedeirosAbstract:Purpose To estimate retinal ganglion cell (RGC) losses associated with visible glaucomatous localized retinal nerve fiber layer (RNFL) defects. Design Observational cross-sectional study. Methods A multicenter study of 198 normal eyes (138 subjects) and 66 glaucomatous eyes (55 subjects) recruited from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. All eyes underwent standard automated perimetry (SAP), spectral-domain optical coherence tomography, and fundus Stereophotography within 6 months. Glaucomatous eyes were included if localized RNFL defects were detected by masked grading of stereophotographs. The number of RGCs in each sector of a structure-function map was estimated using a previously published model combining RGC estimates from SAP and spectral-domain optical coherence tomography. The estimated percentage loss of RGCs (combined structure-function index) was calculated. Results In glaucomatous eyes, there were 136 sectors with visible RNFL defects and 524 sectors without visible RNFL defects. The most common sectors with visible RNFL defects were inferior and inferotemporal sectors, followed by superior and supertemporal sectors. Eyes with visible RNFL defects had a mean estimated RGC count of 657 172 cells versus 968 883 cells in healthy eyes ( P P P Conclusions Although visible localized RNFL defects often are considered an early sign of glaucoma, this study indicates that they are likely to be associated with large neuronal losses.
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Determinants of agreement between the confocal scanning laser tomograph and standardized assessment of glaucomatous progression
Ophthalmology, 2010Co-Authors: Gianmarco Vizzeri, Pamela A. Sample, Robert N. Weinreb, Christopher Bowd, Madhusudhanan Balasubramanian, Felipe A. Medeiros, Linda M. ZangwillAbstract:Purpose To estimate the agreement of confocal scanning laser tomograph (CSLT), topographic change analysis (TCA) with assessment of stereophotographs, and standard automated perimetry (SAP) for detecting glaucomatous progression and to identify factors associated with agreement between methods. Design Observational cohort study. Participants We included 246 eyes of 167 glaucoma patients, glaucoma suspects, and ocular hypertensives. Methods We included CSLT series (n ≥4 tests; mean follow-up, 4 years), stereophotographs, and SAP results in the analysis. The number of progressors by guided progression analysis (GPA, "likely progression"), progressors by masked stereophotographs assessment and progressors by TCA as determined for 3 parameters related to the number of progressed superpixels within the disc margin was determined. Agreement between progression by each TCA parameter, stereophotographs and GPA was assessed using the Kappa test. Analysis of variance with post hoc analysis was applied to identify baseline factors including image quality (standard deviation of the mean topography), disc size and disease severity (pattern standard deviation [PSD] and cup area) associated with agreement/nonagreement between methods. Main Outcome Measures Agreement in assessing glaucomatous progression between the methods including factors associated with agreement/nonagreement between methods. Results Agreement between progression by TCA and progression by stereophotographs and/or GPA was generally poor regardless of the TCA parameter and specificity cutoffs applied. For the parameters with the strongest agreement, cluster size in disc (CSIZE disc ) and cluster area in disc (CAREA disc ), kappa values were 0.16 (63.9%, agreement on 134 nonprogressing eyes and 23 progressing eyes) and 0.15 (64.1%, agreement on 135 nonprogressing eyes and 22 progressing eyes) at 99% cutoff. Most of the factors evaluated were not significantly associated with agreement/nonagreement between methods (all P >0.07). However, SAP PSD was greater in the progressors by Stereophotography only group compared with the progressors by TCA only group (5.8±4.7 and 2.6±2.2, respectively [ P = 0.003] for CSIZE disc at 95% specificity and 5.4±4.6 and 2.5±2.3, respectively [ P = 0.002] for CAREA disc at 99% specificity). Conclusions Agreement for detection of longitudinal changes between TCA, Stereophotography, and SAP GPA is poor. Progressors by Stereophotography only tended to have more advanced disease at baseline than progressors by TCA only. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
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agreement for detecting glaucoma progression with the gdx guided progression analysis automated perimetry and optic disc photography
Ophthalmology, 2010Co-Authors: Linda M. Zangwill, Pamela A. Sample, Robert N. Weinreb, Gianmarco Vizzeri, Christopher Bowd, Felipe A. Medeiros, Luciana M Alencar, Remo SusannaAbstract:Purpose To evaluate the ability of the GDx Variable Corneal Compensation (VCC) Guided Progression Analysis (GPA) software for detecting glaucomatous progression. Design Observational cohort study. Participants The study included 453 eyes from 252 individuals followed for an average of 46±14 months as part of the Diagnostic Innovations in Glaucoma Study. At baseline, 29% of the eyes were classified as glaucomatous, 67% of the eyes were classified as suspects, and 5% of the eyes were classified as healthy. Methods Images were obtained annually with the GDx VCC and analyzed for progression using the Fast Mode of the GDx GPA software. Progression using conventional methods was determined by the GPA software for standard automated achromatic perimetry (SAP) and by masked assessment of optic disc stereophotographs by expert graders. Main Outcome Measures Sensitivity, specificity, and likelihood ratios (LRs) for detection of glaucoma progression using the GDx GPA were calculated with SAP and optic disc stereophotographs used as reference standards. Agreement among the different methods was reported using the AC 1 coefficient. Results Thirty-four of the 431 glaucoma and glaucoma suspect eyes (8%) showed progression by SAP or optic disc stereophotographs. The GDx GPA detected 17 of these eyes for a sensitivity of 50%. Fourteen eyes showed progression only by the GDx GPA with a specificity of 96%. Positive and negative LRs were 12.5 and 0.5, respectively. None of the healthy eyes showed progression by the GDx GPA, with a specificity of 100% in this group. Inter-method agreement (AC 1 coefficient and 95% confidence intervals) for non-progressing and progressing eyes was 0.96 (0.94–0.97) and 0.44 (0.28–0.61), respectively. Conclusions The GDx GPA detected glaucoma progression in a significant number of cases showing progression by conventional methods, with high specificity and high positive LRs. Estimates of the accuracy for detecting progression suggest that the GDx GPA could be used to complement clinical evaluation in the detection of longitudinal change in glaucoma. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
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the relationship between intraocular pressure and progressive retinal nerve fiber layer loss in glaucoma
Ophthalmology, 2009Co-Authors: Felipe A. Medeiros, Linda M. Zangwill, Pamela A. Sample, Luciana M Alencar, Robert N. WeinrebAbstract:Purpose To evaluate the relationship between intraocular pressure (IOP) and progressive retinal nerve fiber layer (RNFL) loss, as measured by scanning laser polarimetry with enhanced corneal compensation (GDx ECC), in a cohort of glaucoma patients and individuals suspected of having the disease followed over time. Design Observational cohort study. Participants The study included 344 eyes of 204 patients recruited from the Diagnostic Innovations in Glaucoma Study (DIGS). There were 98 eyes (28%) with a diagnosis of glaucoma and 246 (72%) were considered glaucoma suspects at baseline. Methods Images were obtained annually with the GDx ECC scanning laser polarimeter, along with stereophotographs and SAP. The study included a total of 1211 GDx ECC visits with an average of 3.5 visits per eye. Progression was determined by the Guided Progression Analysis software for SAP and by masked assessment of stereophotographs performed by expert graders. Main Outcome Measures Random coefficient models were used to evaluate the relationship between IOP and RNFL thickness measurements over time in progressors and nonprogressors. Models were adjusted for baseline diagnosis and central corneal thickness. Results For all 344 eyes, the overall rate of change for the GDx ECC average thickness at an average IOP of 17 mmHg was −0.25 μm per year ( P = 0.002). Each 1-mmHg higher IOP was associated with an additional loss of 0.05 μm per year of RNFL ( P = 0.001). Twenty-nine eyes (8%) showed progression on SAP and/or optic disc stereophotographs. These eyes had a significantly higher rate of RNFL change (−0.95μm/year) than nonprogressors (−0.17 μm/year; P = 0.001). For progressors, each 1-mmHg higher IOP was associated with an additional loss of 0.13 μm per year of RNFL. Conclusions Higher levels of IOP during follow-up were significantly related to higher rates of progressive RNFL loss detected by the GDx ECC. These findings suggest that the GDx ECC may be helpful in monitoring progression and estimating rates of change in patients with glaucoma or suspected of having the disease. Also, they may contribute to a better understanding of the relationship between IOP and structural deterioration in glaucoma. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
Pamela A. Sample - One of the best experts on this subject based on the ideXlab platform.
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Determinants of agreement between the confocal scanning laser tomograph and standardized assessment of glaucomatous progression
Ophthalmology, 2010Co-Authors: Gianmarco Vizzeri, Pamela A. Sample, Robert N. Weinreb, Christopher Bowd, Madhusudhanan Balasubramanian, Felipe A. Medeiros, Linda M. ZangwillAbstract:Purpose To estimate the agreement of confocal scanning laser tomograph (CSLT), topographic change analysis (TCA) with assessment of stereophotographs, and standard automated perimetry (SAP) for detecting glaucomatous progression and to identify factors associated with agreement between methods. Design Observational cohort study. Participants We included 246 eyes of 167 glaucoma patients, glaucoma suspects, and ocular hypertensives. Methods We included CSLT series (n ≥4 tests; mean follow-up, 4 years), stereophotographs, and SAP results in the analysis. The number of progressors by guided progression analysis (GPA, "likely progression"), progressors by masked stereophotographs assessment and progressors by TCA as determined for 3 parameters related to the number of progressed superpixels within the disc margin was determined. Agreement between progression by each TCA parameter, stereophotographs and GPA was assessed using the Kappa test. Analysis of variance with post hoc analysis was applied to identify baseline factors including image quality (standard deviation of the mean topography), disc size and disease severity (pattern standard deviation [PSD] and cup area) associated with agreement/nonagreement between methods. Main Outcome Measures Agreement in assessing glaucomatous progression between the methods including factors associated with agreement/nonagreement between methods. Results Agreement between progression by TCA and progression by stereophotographs and/or GPA was generally poor regardless of the TCA parameter and specificity cutoffs applied. For the parameters with the strongest agreement, cluster size in disc (CSIZE disc ) and cluster area in disc (CAREA disc ), kappa values were 0.16 (63.9%, agreement on 134 nonprogressing eyes and 23 progressing eyes) and 0.15 (64.1%, agreement on 135 nonprogressing eyes and 22 progressing eyes) at 99% cutoff. Most of the factors evaluated were not significantly associated with agreement/nonagreement between methods (all P >0.07). However, SAP PSD was greater in the progressors by Stereophotography only group compared with the progressors by TCA only group (5.8±4.7 and 2.6±2.2, respectively [ P = 0.003] for CSIZE disc at 95% specificity and 5.4±4.6 and 2.5±2.3, respectively [ P = 0.002] for CAREA disc at 99% specificity). Conclusions Agreement for detection of longitudinal changes between TCA, Stereophotography, and SAP GPA is poor. Progressors by Stereophotography only tended to have more advanced disease at baseline than progressors by TCA only. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
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agreement for detecting glaucoma progression with the gdx guided progression analysis automated perimetry and optic disc photography
Ophthalmology, 2010Co-Authors: Linda M. Zangwill, Pamela A. Sample, Robert N. Weinreb, Gianmarco Vizzeri, Christopher Bowd, Felipe A. Medeiros, Luciana M Alencar, Remo SusannaAbstract:Purpose To evaluate the ability of the GDx Variable Corneal Compensation (VCC) Guided Progression Analysis (GPA) software for detecting glaucomatous progression. Design Observational cohort study. Participants The study included 453 eyes from 252 individuals followed for an average of 46±14 months as part of the Diagnostic Innovations in Glaucoma Study. At baseline, 29% of the eyes were classified as glaucomatous, 67% of the eyes were classified as suspects, and 5% of the eyes were classified as healthy. Methods Images were obtained annually with the GDx VCC and analyzed for progression using the Fast Mode of the GDx GPA software. Progression using conventional methods was determined by the GPA software for standard automated achromatic perimetry (SAP) and by masked assessment of optic disc stereophotographs by expert graders. Main Outcome Measures Sensitivity, specificity, and likelihood ratios (LRs) for detection of glaucoma progression using the GDx GPA were calculated with SAP and optic disc stereophotographs used as reference standards. Agreement among the different methods was reported using the AC 1 coefficient. Results Thirty-four of the 431 glaucoma and glaucoma suspect eyes (8%) showed progression by SAP or optic disc stereophotographs. The GDx GPA detected 17 of these eyes for a sensitivity of 50%. Fourteen eyes showed progression only by the GDx GPA with a specificity of 96%. Positive and negative LRs were 12.5 and 0.5, respectively. None of the healthy eyes showed progression by the GDx GPA, with a specificity of 100% in this group. Inter-method agreement (AC 1 coefficient and 95% confidence intervals) for non-progressing and progressing eyes was 0.96 (0.94–0.97) and 0.44 (0.28–0.61), respectively. Conclusions The GDx GPA detected glaucoma progression in a significant number of cases showing progression by conventional methods, with high specificity and high positive LRs. Estimates of the accuracy for detecting progression suggest that the GDx GPA could be used to complement clinical evaluation in the detection of longitudinal change in glaucoma. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
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the relationship between intraocular pressure and progressive retinal nerve fiber layer loss in glaucoma
Ophthalmology, 2009Co-Authors: Felipe A. Medeiros, Linda M. Zangwill, Pamela A. Sample, Luciana M Alencar, Robert N. WeinrebAbstract:Purpose To evaluate the relationship between intraocular pressure (IOP) and progressive retinal nerve fiber layer (RNFL) loss, as measured by scanning laser polarimetry with enhanced corneal compensation (GDx ECC), in a cohort of glaucoma patients and individuals suspected of having the disease followed over time. Design Observational cohort study. Participants The study included 344 eyes of 204 patients recruited from the Diagnostic Innovations in Glaucoma Study (DIGS). There were 98 eyes (28%) with a diagnosis of glaucoma and 246 (72%) were considered glaucoma suspects at baseline. Methods Images were obtained annually with the GDx ECC scanning laser polarimeter, along with stereophotographs and SAP. The study included a total of 1211 GDx ECC visits with an average of 3.5 visits per eye. Progression was determined by the Guided Progression Analysis software for SAP and by masked assessment of stereophotographs performed by expert graders. Main Outcome Measures Random coefficient models were used to evaluate the relationship between IOP and RNFL thickness measurements over time in progressors and nonprogressors. Models were adjusted for baseline diagnosis and central corneal thickness. Results For all 344 eyes, the overall rate of change for the GDx ECC average thickness at an average IOP of 17 mmHg was −0.25 μm per year ( P = 0.002). Each 1-mmHg higher IOP was associated with an additional loss of 0.05 μm per year of RNFL ( P = 0.001). Twenty-nine eyes (8%) showed progression on SAP and/or optic disc stereophotographs. These eyes had a significantly higher rate of RNFL change (−0.95μm/year) than nonprogressors (−0.17 μm/year; P = 0.001). For progressors, each 1-mmHg higher IOP was associated with an additional loss of 0.13 μm per year of RNFL. Conclusions Higher levels of IOP during follow-up were significantly related to higher rates of progressive RNFL loss detected by the GDx ECC. These findings suggest that the GDx ECC may be helpful in monitoring progression and estimating rates of change in patients with glaucoma or suspected of having the disease. Also, they may contribute to a better understanding of the relationship between IOP and structural deterioration in glaucoma. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
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retinal nerve fiber layer thickness measurements with scanning laser polarimetry predict glaucomatous visual field loss
American Journal of Ophthalmology, 2004Co-Authors: Kourosh Mohammadi, Pamela A. Sample, Robert N. Weinreb, Christopher Bowd, Felipe A. Medeiros, Linda M. ZangwillAbstract:Purpose To assess whether baseline retinal nerve fiber layer (RNFL) measurements obtained with a scanning laser polarimeter, the GDx Nerve Fiber Analyzer, (Laser Diagnostic Technologies Inc., San Diego, California) are predictive of development of repeatable glaucomatous visual field damage in glaucoma suspect eyes. Design Cohort study. Methods Participants were recruited from the UCSD longitudinal Diagnostic Innovations in Glaucoma Study (DIGS). One eye from each of 160 glaucoma suspects with normal standard automated perimetry (SAP) visual fields at baseline was studied. Study eyes were divided into convert and nonconvert groups based on the development of three consecutive glaucomatous visual fields during follow-up. SLP parameters, IOP, vertical cup disk ratio, stereophotograph assessment as glaucoma or normal, corneal thickness, and visual field indices were included in univariate and multivariate Cox proportional hazards models to determine which SLP RNFL and ocular parameters were predictive of visual field conversion. Results Sixteen (10%) eyes developed repeatable visual field damage (converts) and 144 (90%) did not (nonconverts). Mean (95%CI) follow-up time until visual field conversion for convert eyes was 2.7 (1.7, 3.6) years. Mean total follow-up of nonconvert eyes was 3.8 (3.5, 4.1) years. Four out of thirteen examined baseline SLP parameters and baseline SAP Mean Deviation (MD), SAP Pattern Standard Deviation (PSD), and glaucomatous stereophotograph assessment were significant univariate predictors of visual field conversion. In multivariate models adjusted for age, IOP and CCT, SLP parameters inferior ratio, ellipse modulation, and UCSD linear discriminant function (LDF) were significant predictors of visual field conversion. When SAP PSD and stereophotograph assessment were also included in the multivariate model inferior ratio and UCSD LDF remained independently predictive of visual field loss. Conclusions Thinner baseline SLP RNFL measurements were independent predictors of visual field damage. In addition to thinner SLP RNFL measurements, higher baseline SAP PSD, and baseline glaucomatous stereophotograph assessment each contributed to an increased risk of the development of abnormal visual fields in glaucoma suspect patients. SLP RNFL measurements were independently predictive of future visual loss even when age, IOP, CCT, vertical cup disk ratio, and SAP PSD were included in the model.
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Short-wavelength automated perimetry and standard perimetry in the detection of progressive optic disc cupping.
Archives of Ophthalmology, 2000Co-Authors: Christopher A. Girkin, Linda M. Zangwill, Pamela A. Sample, Alireza Emdadi, Eytan Z. Blumenthal, Alexander C Lee, Robert N. WeinrebAbstract:Objective To compare progression in short-wavelength automated perimetry (SWAP) and white-on-white (standard) perimetry in eyes with progressive glaucomatous changes of the optic disc detected by serial stereophotographs. Methods Forty-seven glaucoma patients with at least 2 disc stereophotographs more than 2 years apart, along with standard perimetry and SWAP examinations within 6 months of each disc photo of the same eye, were included in the study. The mean follow-up time was 4.1 years (range, 2.0-8.9 years). Baseline and follow-up stereophotographs were then graded and compared for the presence of progression. Progression in standard perimetry and SWAP, using the Advanced Glaucoma Intervention Study scoring system and a clinical scoring system, was compared between eyes with progressive change on stereophotographs and those without. Results Twenty-two of 47 eyes showed progressive change by stereophotographs. There was a statistically significant difference in the mean change in Advanced Glaucoma Intervention Study scores for both standard perimetry ( P P P = .04). Conclusions Short-wavelength automated perimetry identified more patients than standard perimetry as having progressive glaucomatous changes of the optic disc. Compared with standard perimetry, SWAP may improve the detection of progressive glaucoma.
Felipe A. Medeiros - One of the best experts on this subject based on the ideXlab platform.
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Bar graph of the distribution of eyes with visible localized retinal nerve fiber layer (RNFL) defects on optic disc Stereophotography by clock-hour.
2016Co-Authors: Chunwei Zhang, Robert N. Weinreb, Christopher A. Girkin, Felipe A. Medeiros, Andrew J Tatham, Jeffrey M Liebmann, Ricardo Y. Abe, Na’ama Hammel, Akram Belghith, Linda M. ZangwillAbstract:Bar graph of the distribution of eyes with visible localized retinal nerve fiber layer (RNFL) defects on optic disc Stereophotography by clock-hour.
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estimated retinal ganglion cell counts in glaucomatous eyes with localized retinal nerve fiber layer defects
American Journal of Ophthalmology, 2013Co-Authors: Andrew J Tatham, Linda M. Zangwill, Robert N. Weinreb, Christopher A. Girkin, Jeffrey M Liebmann, Felipe A. MedeirosAbstract:Purpose To estimate retinal ganglion cell (RGC) losses associated with visible glaucomatous localized retinal nerve fiber layer (RNFL) defects. Design Observational cross-sectional study. Methods A multicenter study of 198 normal eyes (138 subjects) and 66 glaucomatous eyes (55 subjects) recruited from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. All eyes underwent standard automated perimetry (SAP), spectral-domain optical coherence tomography, and fundus Stereophotography within 6 months. Glaucomatous eyes were included if localized RNFL defects were detected by masked grading of stereophotographs. The number of RGCs in each sector of a structure-function map was estimated using a previously published model combining RGC estimates from SAP and spectral-domain optical coherence tomography. The estimated percentage loss of RGCs (combined structure-function index) was calculated. Results In glaucomatous eyes, there were 136 sectors with visible RNFL defects and 524 sectors without visible RNFL defects. The most common sectors with visible RNFL defects were inferior and inferotemporal sectors, followed by superior and supertemporal sectors. Eyes with visible RNFL defects had a mean estimated RGC count of 657 172 cells versus 968 883 cells in healthy eyes ( P P P Conclusions Although visible localized RNFL defects often are considered an early sign of glaucoma, this study indicates that they are likely to be associated with large neuronal losses.
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Determinants of agreement between the confocal scanning laser tomograph and standardized assessment of glaucomatous progression
Ophthalmology, 2010Co-Authors: Gianmarco Vizzeri, Pamela A. Sample, Robert N. Weinreb, Christopher Bowd, Madhusudhanan Balasubramanian, Felipe A. Medeiros, Linda M. ZangwillAbstract:Purpose To estimate the agreement of confocal scanning laser tomograph (CSLT), topographic change analysis (TCA) with assessment of stereophotographs, and standard automated perimetry (SAP) for detecting glaucomatous progression and to identify factors associated with agreement between methods. Design Observational cohort study. Participants We included 246 eyes of 167 glaucoma patients, glaucoma suspects, and ocular hypertensives. Methods We included CSLT series (n ≥4 tests; mean follow-up, 4 years), stereophotographs, and SAP results in the analysis. The number of progressors by guided progression analysis (GPA, "likely progression"), progressors by masked stereophotographs assessment and progressors by TCA as determined for 3 parameters related to the number of progressed superpixels within the disc margin was determined. Agreement between progression by each TCA parameter, stereophotographs and GPA was assessed using the Kappa test. Analysis of variance with post hoc analysis was applied to identify baseline factors including image quality (standard deviation of the mean topography), disc size and disease severity (pattern standard deviation [PSD] and cup area) associated with agreement/nonagreement between methods. Main Outcome Measures Agreement in assessing glaucomatous progression between the methods including factors associated with agreement/nonagreement between methods. Results Agreement between progression by TCA and progression by stereophotographs and/or GPA was generally poor regardless of the TCA parameter and specificity cutoffs applied. For the parameters with the strongest agreement, cluster size in disc (CSIZE disc ) and cluster area in disc (CAREA disc ), kappa values were 0.16 (63.9%, agreement on 134 nonprogressing eyes and 23 progressing eyes) and 0.15 (64.1%, agreement on 135 nonprogressing eyes and 22 progressing eyes) at 99% cutoff. Most of the factors evaluated were not significantly associated with agreement/nonagreement between methods (all P >0.07). However, SAP PSD was greater in the progressors by Stereophotography only group compared with the progressors by TCA only group (5.8±4.7 and 2.6±2.2, respectively [ P = 0.003] for CSIZE disc at 95% specificity and 5.4±4.6 and 2.5±2.3, respectively [ P = 0.002] for CAREA disc at 99% specificity). Conclusions Agreement for detection of longitudinal changes between TCA, Stereophotography, and SAP GPA is poor. Progressors by Stereophotography only tended to have more advanced disease at baseline than progressors by TCA only. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
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agreement for detecting glaucoma progression with the gdx guided progression analysis automated perimetry and optic disc photography
Ophthalmology, 2010Co-Authors: Linda M. Zangwill, Pamela A. Sample, Robert N. Weinreb, Gianmarco Vizzeri, Christopher Bowd, Felipe A. Medeiros, Luciana M Alencar, Remo SusannaAbstract:Purpose To evaluate the ability of the GDx Variable Corneal Compensation (VCC) Guided Progression Analysis (GPA) software for detecting glaucomatous progression. Design Observational cohort study. Participants The study included 453 eyes from 252 individuals followed for an average of 46±14 months as part of the Diagnostic Innovations in Glaucoma Study. At baseline, 29% of the eyes were classified as glaucomatous, 67% of the eyes were classified as suspects, and 5% of the eyes were classified as healthy. Methods Images were obtained annually with the GDx VCC and analyzed for progression using the Fast Mode of the GDx GPA software. Progression using conventional methods was determined by the GPA software for standard automated achromatic perimetry (SAP) and by masked assessment of optic disc stereophotographs by expert graders. Main Outcome Measures Sensitivity, specificity, and likelihood ratios (LRs) for detection of glaucoma progression using the GDx GPA were calculated with SAP and optic disc stereophotographs used as reference standards. Agreement among the different methods was reported using the AC 1 coefficient. Results Thirty-four of the 431 glaucoma and glaucoma suspect eyes (8%) showed progression by SAP or optic disc stereophotographs. The GDx GPA detected 17 of these eyes for a sensitivity of 50%. Fourteen eyes showed progression only by the GDx GPA with a specificity of 96%. Positive and negative LRs were 12.5 and 0.5, respectively. None of the healthy eyes showed progression by the GDx GPA, with a specificity of 100% in this group. Inter-method agreement (AC 1 coefficient and 95% confidence intervals) for non-progressing and progressing eyes was 0.96 (0.94–0.97) and 0.44 (0.28–0.61), respectively. Conclusions The GDx GPA detected glaucoma progression in a significant number of cases showing progression by conventional methods, with high specificity and high positive LRs. Estimates of the accuracy for detecting progression suggest that the GDx GPA could be used to complement clinical evaluation in the detection of longitudinal change in glaucoma. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
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the relationship between intraocular pressure and progressive retinal nerve fiber layer loss in glaucoma
Ophthalmology, 2009Co-Authors: Felipe A. Medeiros, Linda M. Zangwill, Pamela A. Sample, Luciana M Alencar, Robert N. WeinrebAbstract:Purpose To evaluate the relationship between intraocular pressure (IOP) and progressive retinal nerve fiber layer (RNFL) loss, as measured by scanning laser polarimetry with enhanced corneal compensation (GDx ECC), in a cohort of glaucoma patients and individuals suspected of having the disease followed over time. Design Observational cohort study. Participants The study included 344 eyes of 204 patients recruited from the Diagnostic Innovations in Glaucoma Study (DIGS). There were 98 eyes (28%) with a diagnosis of glaucoma and 246 (72%) were considered glaucoma suspects at baseline. Methods Images were obtained annually with the GDx ECC scanning laser polarimeter, along with stereophotographs and SAP. The study included a total of 1211 GDx ECC visits with an average of 3.5 visits per eye. Progression was determined by the Guided Progression Analysis software for SAP and by masked assessment of stereophotographs performed by expert graders. Main Outcome Measures Random coefficient models were used to evaluate the relationship between IOP and RNFL thickness measurements over time in progressors and nonprogressors. Models were adjusted for baseline diagnosis and central corneal thickness. Results For all 344 eyes, the overall rate of change for the GDx ECC average thickness at an average IOP of 17 mmHg was −0.25 μm per year ( P = 0.002). Each 1-mmHg higher IOP was associated with an additional loss of 0.05 μm per year of RNFL ( P = 0.001). Twenty-nine eyes (8%) showed progression on SAP and/or optic disc stereophotographs. These eyes had a significantly higher rate of RNFL change (−0.95μm/year) than nonprogressors (−0.17 μm/year; P = 0.001). For progressors, each 1-mmHg higher IOP was associated with an additional loss of 0.13 μm per year of RNFL. Conclusions Higher levels of IOP during follow-up were significantly related to higher rates of progressive RNFL loss detected by the GDx ECC. These findings suggest that the GDx ECC may be helpful in monitoring progression and estimating rates of change in patients with glaucoma or suspected of having the disease. Also, they may contribute to a better understanding of the relationship between IOP and structural deterioration in glaucoma. Financial Disclosure(s) Proprietary or commercial disclosure may be found after the references.
Christopher A. Girkin - One of the best experts on this subject based on the ideXlab platform.
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Bar graph of the distribution of eyes with visible localized retinal nerve fiber layer (RNFL) defects on optic disc Stereophotography by clock-hour.
2016Co-Authors: Chunwei Zhang, Robert N. Weinreb, Christopher A. Girkin, Felipe A. Medeiros, Andrew J Tatham, Jeffrey M Liebmann, Ricardo Y. Abe, Na’ama Hammel, Akram Belghith, Linda M. ZangwillAbstract:Bar graph of the distribution of eyes with visible localized retinal nerve fiber layer (RNFL) defects on optic disc Stereophotography by clock-hour.
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estimated retinal ganglion cell counts in glaucomatous eyes with localized retinal nerve fiber layer defects
American Journal of Ophthalmology, 2013Co-Authors: Andrew J Tatham, Linda M. Zangwill, Robert N. Weinreb, Christopher A. Girkin, Jeffrey M Liebmann, Felipe A. MedeirosAbstract:Purpose To estimate retinal ganglion cell (RGC) losses associated with visible glaucomatous localized retinal nerve fiber layer (RNFL) defects. Design Observational cross-sectional study. Methods A multicenter study of 198 normal eyes (138 subjects) and 66 glaucomatous eyes (55 subjects) recruited from the Diagnostic Innovations in Glaucoma Study and the African Descent and Glaucoma Evaluation Study. All eyes underwent standard automated perimetry (SAP), spectral-domain optical coherence tomography, and fundus Stereophotography within 6 months. Glaucomatous eyes were included if localized RNFL defects were detected by masked grading of stereophotographs. The number of RGCs in each sector of a structure-function map was estimated using a previously published model combining RGC estimates from SAP and spectral-domain optical coherence tomography. The estimated percentage loss of RGCs (combined structure-function index) was calculated. Results In glaucomatous eyes, there were 136 sectors with visible RNFL defects and 524 sectors without visible RNFL defects. The most common sectors with visible RNFL defects were inferior and inferotemporal sectors, followed by superior and supertemporal sectors. Eyes with visible RNFL defects had a mean estimated RGC count of 657 172 cells versus 968 883 cells in healthy eyes ( P P P Conclusions Although visible localized RNFL defects often are considered an early sign of glaucoma, this study indicates that they are likely to be associated with large neuronal losses.
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discrimination between glaucomatous and nonglaucomatous eyes using quantitative imaging devices and subjective optic nerve head assessment
Investigative Ophthalmology & Visual Science, 2006Co-Authors: Julio Deleonortega, Stella N Arthur, Gerald Mcgwin, Aiyuan Xie, Blythe E Monheit, Christopher A. GirkinAbstract:In an effort to detect and document changes indicative of glaucoma at earlier stages, a variety of techniques have evolved to provide quantitative estimates of optic nerve head (ONH) topography, retinal nerve fiber layer (RNFL) thickness, and macular thickness. Several studies have demonstrated that in prior versions each of some of these techniques discriminate between glaucomatous and normal populations with a high degree of sensitivity and specificity.1–5 However, few studies have compared the diagnostic performance of these instruments in the same study population and in comparison to subjective assessment of the ONH.1,3 These prior studies used older versions of the instruments and demonstrated that objective optic nerve imaging modalities were equivalent to subjective assessment performed by masked expert stereophotograph graders. Since the earlier studies, significant modifications have occurred with each of these quantitative imaging techniques that have improved their ability to detect glaucomatous damage. With scanning laser polarimetry (GDx-VCC; Carl Zeiss Meditec, Inc., Dublin, CA), a conversion to variable corneal compensation that provides individualized adjustment of anterior segment birefringence has improved the sensitivity and specificity of this technique.6,7 The current generation of optical coherence tomography (StratusOCT; Carl Zeiss Meditec, Inc.) has increased scan rate and scan resolution and can also be used to obtain macular and ONH measurements.8 The most recent version of the confocal scanning laser ophthalmoscope (HRT II; Heidelberg Engineering, Heidelberg, Germany) has been modified significantly with automation of the examination procedure focused on optic disc topography, which has improved the reproducibility and efficacy of this instrument in the detection of glaucoma.2,4,9,10 A recent study by Medeiros et al.11 using the current version of these instruments has demonstrated that each performs with similar efficacy in the diagnosis of glaucoma. However, there was no comparison between these new versions of objective imaging methods with subjective ONH evaluation or objective evaluation of the optic nerve head with ONH analysis and macular thickness from StratusOCT. The purpose of this study was to compare the diagnostic ability of the confocal scanning laser ophthalmoscopy with the HRT II, scanning laser polarimetry with the GDX-VCC, and retinal nerve fiber layer thickness, ONH analysis and macular thickness measurements with the StratusOCT with subjective masked expert assessment of stereophotographs in the same study population.
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Short-wavelength automated perimetry and standard perimetry in the detection of progressive optic disc cupping.
Archives of Ophthalmology, 2000Co-Authors: Christopher A. Girkin, Linda M. Zangwill, Pamela A. Sample, Alireza Emdadi, Eytan Z. Blumenthal, Alexander C Lee, Robert N. WeinrebAbstract:Objective To compare progression in short-wavelength automated perimetry (SWAP) and white-on-white (standard) perimetry in eyes with progressive glaucomatous changes of the optic disc detected by serial stereophotographs. Methods Forty-seven glaucoma patients with at least 2 disc stereophotographs more than 2 years apart, along with standard perimetry and SWAP examinations within 6 months of each disc photo of the same eye, were included in the study. The mean follow-up time was 4.1 years (range, 2.0-8.9 years). Baseline and follow-up stereophotographs were then graded and compared for the presence of progression. Progression in standard perimetry and SWAP, using the Advanced Glaucoma Intervention Study scoring system and a clinical scoring system, was compared between eyes with progressive change on stereophotographs and those without. Results Twenty-two of 47 eyes showed progressive change by stereophotographs. There was a statistically significant difference in the mean change in Advanced Glaucoma Intervention Study scores for both standard perimetry ( P P P = .04). Conclusions Short-wavelength automated perimetry identified more patients than standard perimetry as having progressive glaucomatous changes of the optic disc. Compared with standard perimetry, SWAP may improve the detection of progressive glaucoma.
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visual function specific perimetry for indirect comparison of different ganglion cell populations in glaucoma
Investigative Ophthalmology & Visual Science, 2000Co-Authors: Pamela A. Sample, Christopher A. Girkin, Eytan Z. Blumenthal, Charles F Bosworth, Robert N. WeinrebAbstract:PURPOSE To compare short-wavelength automated perimetry, frequency-doubling technology perimetry, and motion-automated perimetry, each of which assesses different aspects of visual function, in eyes with glaucomatous optic neuropathy and ocular hypertension. METHODS One hundred thirty-six eyes from 136 subjects were evaluated with all three tests as well as with standard automated perimetry. Fields were not used in the classification of study groups to prevent bias, because the major purpose of the study was to evaluate each field type relative to the others. Seventy-one of the 136 eyes had glaucomatous optic neuropathy, 37 had ocular hypertension, and 28 served as age-matched normal control eyes. Glaucomatous optic neuropathy was defined by assessment of stereophotographs. Criteria were asymmetrical cupping, the presence of rim thinning, notching, excavation, or nerve fiber layer defect. Ocular hypertensive eyes had intraocular pressure of 23 mm Hg or more on at least two occasions and normal-appearing optic disc stereophotographs. Criteria for abnormality on each visual field test were selected to approximate a specificity of 90% in the normal eyes. Thresholds for each of the four tests were compared, to determine the percentage that were abnormal within each patient group and to assess the agreement among test results for abnormality, location, and extent of visual field deficit. RESULTS Each test identified a subset of the eyes with glaucomatous optic neuropathy as abnormal: 46% with standard perimetry, 61% with short-wavelength automated perimetry, 70% with frequency-doubling perimetry, and 52% with motion-automated perimetry. In the ocular hypertensive eyes, standard perimetry was abnormal in 5%, short wavelength in 22%, frequency doubling in 46%, and motion in 30%. Fifty-four percent (38/71) of eyes with glaucomatous optic neuropathy were normal on standard fields. However, 90% were identified by at least one of the specific visual function tests. Combining tests improved sensitivity with slight reductions in specificity. The agreement in at least one quadrant, when a defect was present with more than one test, was very high at 92% to 97%. More extensive deficits were shown by frequency-doubling perimetry followed by short-wavelength automated perimetry, then motion-automated perimetry, and last, standard perimetry. However, there were significant individual differences in which test of any given pairing was more extensively affected. Only 30% (11/37) of the ocular hypertensive eyes showed no deficits at all compared with 71% (20/28) of the control eyes (P < 0.001). CONCLUSIONS For detection of functional loss standard visual field testing is not optimum; a combination of two or more tests may improve detection of functional loss in these eyes; in an individual, the same retinal location is damaged, regardless of visual function under test; glaucomatous optic neuropathy identified on stereophotographs may precede currently measurable function loss in some eyes; conversely, function loss with specific tests may precede detection of abnormality by stereophotograph review; and short-wavelength automated perimetry, frequency-doubling perimetry, and motion-automated perimetry continue to show promise as early indicators of function loss in glaucoma.
