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David P Crabb - One of the best experts on this subject based on the ideXlab platform.
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glaucoma home monitoring using a tablet based Visual Field Test eyecatcher an assessment of accuracy and adherence over six months
American Journal of Ophthalmology, 2020Co-Authors: Pete R Jones, Peter Campbell, Tamsin Callaghan, Lee Jones, Daniel S Asfaw, David F Edgar, David P CrabbAbstract:Abstract Purpose To assess accuracy and adherence of Visual Field (VF) home-monitoring in a pilot sample of glaucoma patients. Design Prospective longitudinal feasibility and reliability study. Methods Twenty adults (median 71 years) with an established diagnosis of glaucoma were issued a tablet-perimeter (Eyecatcher), and were asked to perform one VF home-assessment per eye, per month, for 6 months (12 Tests total). Before and after home-monitoring, two VF assessments were performed in-clinic using Standard Automated Perimetry (SAP; 4 Tests total, per eye). Results All 20 participants could perform monthly home-monitoring, though one participant stopped after 4 months (Adherence: 98%). There was good concordance between VFs measured at home and in the clinic (r = 0.94, P Conclusions Home-monitoring of VFs is viable for some patients, and may provide clinically useful data.
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glaucoma home monitoring using a tablet based Visual Field Test eyecatcher an assessment of accuracy and adherence over six months
medRxiv, 2020Co-Authors: Pete R Jones, Peter Campbell, Tamsin Callaghan, Lee Jones, Daniel S Asfaw, David F Edgar, David P CrabbAbstract:Purpose: To assess accuracy and adherence of Visual Field (VF) home-monitoring in a pilot sample of glaucoma patients. Design: Prospective longitudinal observation. Methods: Twenty adults (median 71 years) with an established diagnosis of glaucoma were issued a tablet-perimeter (Eyecatcher), and were asked to perform one VF home-assessment per eye, per month, for 6 months (12 Tests total). Before and after home-monitoring, two VF assessments were performed in-clinic using Standard Automated Perimetry (SAP; 4 Tests total, per eye). Results: All 20 participants could perform monthly home-monitoring, though one participant stopped after 4 months (Adherence: 98%). There was good concordance between VFs measured at home and in the clinic (r = 0.94, P < 0.001). In 21 of 236 Tests (9%) Mean Deviation deviated by more than {+/-}3 dB from the median. Many of these anomalous Tests could be identified by applying machine learning techniques to recordings from the tablets' front-facing camera (Area Under the ROC Curve = 0.78). Adding home-monitoring data to 2 SAP Tests made 6 months apart reduced measurement error (between-Test measurement variability) in 97% of eyes, with mean absolute error more than halving in 90% of eyes. Median Test duration was 4.5 mins (Quartiles: 3.9 - 5.2 mins). Substantial variations in ambient illumination had no observable effect on VF measurements (r = 0.07, P = 0.320). Conclusions: Home-monitoring of VFs is viable for some patients, and may provide clinically useful data.
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Exploring Early Glaucoma and the Visual Field Test: Classification and Clustering Using Bayesian Networks
IEEE Journal of Biomedical and Health Informatics, 2014Co-Authors: Stefano Ceccon, David P Crabb, David F. Garway-heath, Allan TuckerAbstract:Bayesian networks (BNs) are probabilistic models used for classification and clustering in several Fields. Their ability to deal with unobserved variables and to integrate data and expert knowledge make them an appropriate technique for modeling eye functionality measurements in glaucoma. In this study, a set of BNs is used to simultaneously perform classification of early glaucoma and cluster data into different stages of disease. A novel learning algorithm that combines clustering and quasi-greedy search is also proposed. The classification performances of the models are evaluated on an independent dataset, while the clusters are compared to K-means, previous publications, and direct knowledge. The use of clustering and structure learning enabled the exploration of the Visual Field patterns of the disease while obtaining good results both on pre- (50% sensitivity at 90% specificity) and post- (85% sensitivity at 90% specificity) diagnosis data. Clusters obtained were insightful and in conformity with consolidated knowledge in the Field.
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a survey of attitudes of glaucoma subspecialists in england and wales to Visual Field Test intervals in relation to nice guidelines
BMJ Open, 2013Co-Authors: Rizwan Malik, Richard A Russell, Helen Baker, David P CrabbAbstract:Objectives To establish the attitudes of glaucoma specialists to the frequency of Visual Field (VF) Testing in the UK, using the NICE recommendations as a standard for ideal practice. Design Interview and postal survey. Setting UK and Eire Glaucoma Society national meeting 2011 in Manchester, UK, with a second round of surveys administered by post. Participants All consultant glaucoma specialists in England and Wales were invited to complete the survey. Primary and secondary outcome measures (1) Compliance of assigned follow-up VF intervals with NICE guidelines for three hypothetical patient scenarios, with satisfactory treated intraocular pressure and (a) no evidence of VF progression; (b) evidence of VF progression and (c) uncertainty about VF progression, and respondents were asked to provide typical follow-up intervals representative of their practice; (2) attitudes to research recommendations for six VF in the first 2 years for newly diagnosed patients with glaucoma. Results 70 glaucoma specialists completed the survey. For each of the clinical scenarios a, b and c, 14 (20%), 33 (47%) and 28 (40%) responses, respectively, fell outside the follow-up interval recommended by NICE. Nearly half of the specialists (46%) agreed that 6 VF Tests in the first 2 years was ideal practice, while 16 (28%) said this was practice ‘not possible’, with many giving resources within the NHS setting as a limiting factor. Conclusions The results from this survey suggest that there is a large variation in attitudes to follow-up intervals for patients with glaucoma in the UK, with assigned intervals for VF Testing which are, in many cases, inconsistent with the guidelines from NICE.
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a novel distribution of Visual Field Test points to improve the correlation between structure function measurements
Investigative Ophthalmology & Visual Science, 2012Co-Authors: R Asaoka, David P Crabb, David F Garwayheath, Richard A Russell, Rizwan MalikAbstract:PURPOSE: To create a new Visual Field (VF) Test grid centered at the optic disc (disc-centered Field [DCF]) and to infer the combination of VF Test points (structure-function Field [SFF]), taken from the DCF and the conventional fovea-centered 24-2 grid (24-2) of standard automated perimetry, which yields the strongest sectorial correlation between structure-function measurements of retinal nerve fiber layer (RNFL) thickness and VF sensitivity. METHODS: In 50 eyes with ocular hypertension or open angle glaucoma, the DCF and 24-2 VF were measured with a humphrey Field analyzer II (Full Threshold strategy) and RNFL thickness was measured with Stratus optical coherence tomography. Test points from the DCF and 24-2 VF Were combined and divided into 12 sectors according to the spatial distribution of the RNFL. A novel VF for structure-function studies was established using the following criteria: each sector must contain at least one or two Test points (depending on the sector's location), and the combination of Test points which yields the strongest structure-function correlation is selected. RESULTS: The SFF consisted of 40 Test points. The structure-function correlation for the SFF was compared with the standard 24-2 VF; a multiple-comparison Test for dependent groups was carried out using a percentile bootstrap method, which indicated that the sector correlation coefficients in the SFF were significantly higher than those in the 24-2 VF. CONCLUSIONS: The SFF, with fewer Test locations, has a stronger structure-function correlation than the 24-2 VF. This improved correlation may help clinicians to better interpret functional measurements in relation to structural measurements.
Wolfgang Fink - One of the best experts on this subject based on the ideXlab platform.
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Portable system to monitor astronaut ocular health and the development of the VIIP Syndrome
2014 IEEE Aerospace Conference, 2014Co-Authors: Wolfgang Fink, David C. Hilmers, Mark A. TarbellAbstract:We propose to utilize a previously developed, deployed, and clinically Tested comprehensive Visual Field Test and diagnosis system to investigate the relationship between intracranial pressure (ICP) and intraocular pressure (IOP) elevations that occur during long-term space travel and Visual Field loss. Recent data describing this phenomenon, now called the Visual Impairment/Intracranial Pressure (VIIP) Syndrome raise concerns that it could impact the Visual health of astronauts both during long-duration space travel, potentially causing an impact to the mission, and after flight, causing significant morbidity. A non-invasive, easily-deployable, user-friendly Visual Field Test system can provide early detection of changes in vision in flight as well as a screening and research tool to help develop countermeasures to prevent/alleviate this problem and to identify at-risk astronauts.
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Comprehensive Visual Field Test & diagnosis system in support of astronaut health and performance
2013 IEEE Aerospace Conference, 2013Co-Authors: Wolfgang Fink, Jonathan B. Clark, Garrett E. Reisman, Mark A. TarbellAbstract:Long duration spaceflight, permanent human presence on the Moon, and future human missions to Mars will require autonomous medical care to address both expected and unexpected risks. An integrated non-invasive Visual Field Test & diagnosis system is presented for the identification, characterization, and automated classification of Visual Field defects caused by the spaceflight environment. This system will support the onboard medical provider and astronauts on space missions with an innovative, non-invasive, accurate, sensitive, and fast Visual Field Test. It includes a database for examination data, and a software package for automated Visual Field analysis and diagnosis. The system will be used to detect and diagnose conditions affecting the Visual Field, while in space and on Earth, permitting the timely application of therapeutic countermeasures before astronaut health or performance are impaired. State-of-the-art perimetry devices are bulky, thereby precluding application in a spaceflight setting. In contrast, the Visual Field Test & diagnosis system requires only a touchscreen-equipped computer or touchpad device, which may already be in use for other purposes (i.e., no additional payload), and custom software. The system has application in routine astronaut assessment (Clinical Status Exam), pre-, in-, and post-flight monitoring, and astronaut selection. It is deployable in operational space environments, such as aboard the International Space Station or during future missions to or permanent presence on the Moon and Mars.
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comprehensive Visual Field Test diagnosis system in support of astronaut health and performance
IEEE Aerospace Conference, 2013Co-Authors: Wolfgang Fink, Jonathan B. Clark, Garrett E. Reisman, Mark A. TarbellAbstract:Long duration spaceflight, permanent human presence on the Moon, and future human missions to Mars will require autonomous medical care to address both expected and unexpected risks. An integrated non-invasive Visual Field Test & diagnosis system is presented for the identification, characterization, and automated classification of Visual Field defects caused by the spaceflight environment. This system will support the onboard medical provider and astronauts on space missions with an innovative, non-invasive, accurate, sensitive, and fast Visual Field Test. It includes a database for examination data, and a software package for automated Visual Field analysis and diagnosis. The system will be used to detect and diagnose conditions affecting the Visual Field, while in space and on Earth, permitting the timely application of therapeutic countermeasures before astronaut health or performance are impaired. State-of-the-art perimetry devices are bulky, thereby precluding application in a spaceflight setting. In contrast, the Visual Field Test & diagnosis system requires only a touchscreen-equipped computer or touchpad device, which may already be in use for other purposes (i.e., no additional payload), and custom software. The system has application in routine astronaut assessment (Clinical Status Exam), pre-, in-, and post-flight monitoring, and astronaut selection. It is deployable in operational space environments, such as aboard the International Space Station or during future missions to or permanent presence on the Moon and Mars.
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early detection of glaucoma by means of a novel 3d computer automated Visual Field Test
British Journal of Ophthalmology, 2007Co-Authors: Paul P Nazemi, Wolfgang Fink, Alfredo A Sadun, Brian A Francis, Don S MincklerAbstract:Purpose: A recently devised 3D computer-automated threshold Amsler grid Test was used to identify early and distinctive defects in people with suspected glaucoma. Further, the location, shape and depth of these Field defects were characterised. Finally, the Visual Fields were compared with those obtained by standard automated perimetry. Patients and methods: Glaucoma suspects were defined as those having elevated intraocular pressure (>21 mm Hg) or cup-to-disc ratio of >0.5. 33 patients and 66 eyes with risk factors for glaucoma were examined. 15 patients and 23 eyes with no risk factors were Tested as controls. The recently developed 3D computer-automated threshold Amsler grid Test was used. The Test exhibits a grid on a computer screen at a preselected greyscale and angular resolution, and allows patients to trace those areas on the grid that are missing in their Visual Field using a touch screen. The 5-minute Test required that the patients repeatedly outline scotomas on a touch screen with varied displays of contrast while maintaining their gaze on a central fixation marker. A 3D depiction of the Visual Field defects was then obtained that was further characterised by the location, shape and depth of the scotomas. The exam was repeated three times per eye. The results were compared to Humphrey Visual Field Tests (ie, achromatic standard or SITA standard 30-2 or 24-2). Results: In this pilot study 79% of the eyes Tested in the glaucoma-suspect group repeatedly demonstrated Visual Field loss with the 3D perimetry. The 3D depictions of Visual Field loss associated with these risk factors were all characteristic of or compatible with glaucoma. 71% of the eyes demonstrated arcuate defects or a nasal step. Constricted Visual Fields were shown in 29% of the eyes. No Visual Field changes were detected in the control group. Conclusions: The 3D computer-automated threshold Amsler grid Test may demonstrate Visual Field abnormalities characteristic of glaucoma in glaucoma suspects with normal achromatic Humphrey Visual Field Testing. This Test may be used as a screening tool for the early detection of glaucoma.
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scotomas of age related macular degeneration detected and characterized by means of a novel three dimensional computer automated Visual Field Test
Retina-the Journal of Retinal and Vitreous Diseases, 2005Co-Authors: Paul P Nazemi, Wolfgang Fink, Alfredo A SadunAbstract:Purpose:We used the recently devised three-dimensional computer-based threshold Amsler grid Test to acquire and identify typical patterns of Visual Field defects (scotomas) caused by age-related macular degeneration (AMD).Methods:Patients with AMD traced on a computer touch screen the borders of tho
David B. Henson - One of the best experts on this subject based on the ideXlab platform.
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diagnostic performance and repeatability of a novel game based Visual Field Test for children
Investigative Ophthalmology & Visual Science, 2018Co-Authors: David B. Henson, Cecilia Fenerty, Susmito Biswas, Tariq Aslam, Yanfang Wang, Emmanouil TsamisAbstract:Purpose: To demonstrate utility of a game-based Test ("Caspar's Castle") for the detection of Visual Field defects in children. Methods: A validity and reliability study was carried out at Manchester Royal Eye Hospital Pediatric Ophthalmology Outpatients Department. We recruited 108 children with no eye pathology (aged 4-12 years) and examined a single eye with the Caspar's Castle system using either normal thresholds or thresholds artificially adapted to recreate defects to assess diagnostic utility. Number of peripheral stimuli missed was used to determine sensitivity and specificity of artificial defect detection and to plot receiver-operator characteristic curves. A further 21 children (aged 4-16 years) with pathology were recruited and Caspar's Fields compared qualitatively with established Field Testing. A total of 106 of the Caspar's Castle examinations were able to be performed twice and repeatability was determined through coefficient of repeatability and Bland-Altman chart. Results: In diagnostic Testing using children with no eye pathology, 45 children completed a Test using normal thresholds and 43 with Tests using artificial defects. Area under receiver-operator characteristic curves for artificial defect detection was 0.895. Of the 21 children with pathology, seven had completed standard Humphreys Field Testing and Caspar's Castle Fields corresponded with each of these by expert opinion. Coefficient of repeatability for number of points missed across all cohorts of children (106 patients) was 6.9 (95% confidence interval: 6.16-8.07). Conclusions: The Caspar's Castle system of assessing Visual Fields using novel game-based strategies demonstrates encouraging levels of sensitivity, specificity, and reliability. It could help address current difficulties in perimetry in young children.
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normal threshold size of stimuli in children using a game based Visual Field Test
Ophthalmology and therapy, 2017Co-Authors: Yanfang Wang, David B. Henson, Cecilia Fenerty, Susmito Biswas, Siddharth Subramani, Tariq AslamAbstract:Introduction The aim of this study was to demonstrate and explore the ability of novel game-based perimetry to establish normal Visual Field thresholds in children.
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development of a pediatric Visual Field Test
Translational Vision Science & Technology, 2016Co-Authors: David B. Henson, Marco A Miranda, Cecilia Fenerty, Susmito Biswas, Tariq AslamAbstract:PURPOSE: We describe a pediatric Visual Field (VF) Test based on a computer game where software and hardware combine to provide an enjoyable Test experience. METHODS: The Test software consists of a platform-based computer game presented to the central VF. A storyline was created around the game as was a structure surrounding the computer monitor to enhance patients' experience. The patient is asked to help the central character collect magic coins (stimuli). To collect these coins a series of obstacles need to be overcome. The Test was presented on a Sony PVM-2541A monitor calibrated from a central midpoint with a Minolta CS-100 photometer placed at 50 cm. Measurements were performed at 15 locations on the screen and the contrast calculated. Retinal sensitivity was determined by modulating stimulus in size. To Test the feasibility of the novel approach 20 patients (4–16 years old) with no history of VF defects were recruited. RESULTS: For the 14 subjects completing the study, 31 ± 15 data points were collected on 1 eye of each patient. Mean background luminance and stimulus contrast were 9.9 ± 0.3 cd/m2 and 27.9 ± 0.1 dB, respectively. Sensitivity values obtained were similar to an adult population but variability was considerably higher – 8.3 ± 9.0 dB. CONCLUSIONS: Preliminary data show the feasibility of a game-based VF Test for pediatric use. Although the Test was well accepted by the target population, Test variability remained very high. TRANSLATIONAL RELEVANCE: Traditional VF Tests are not well tolerated by children. This study describes a child-friendly approach to Test Visual Fields in the targeted population.
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diagnostic performance of Visual Field Test using subsets of the 24 2 Test pattern for early glaucomatous Field loss
Investigative Ophthalmology & Visual Science, 2013Co-Authors: Yanfang Wang, David B. HensonAbstract:PURPOSE. To explore the diagnostic performance of threshold Visual Field Tests using subsets of the standard 24-2 Test pattern in detecting early/moderate glaucomatous Field loss. METHODS. Normal (Brusini stage 0, n ¼2344) and defective eyes (Brusini stage 2‐3, n ¼ 2222) from a database of Visual Field Tests (6696 eyes/3586 patients, SITA standard 24-2 algorithm) were selected and resampled using a bootstrap method. The positive predictive values (PPVs) of each Test location were calculated for the resampled datasets with a fail criteria of a single missed stimulus at a pattern deviation probability level of less than 0.01. Optimized Test patterns started with the most frequent location of the maximum PPV in datasets. Eyes missing the location were removed and the PPV values of residual sample recalculated. The process was repeated until all defective eyes were detected. Receiver operating characteristic (ROC) curves were established for the PPV-optimized and five randomized patterns. Characteristics of Visual Field defects detected with subsets of optimized Test pattern were established. RESULTS. With the PPV-optimized pattern, 95% of the Field defects were detected with 30 locations and all with 43 locations. Areas under the ROC curve were greaTest for the optimized pattern. With each increment in the number of Test locations, the Mean Deviation of additionally detected eyes became more positive while Pattern Standard Deviation became less positive (P < 0.001). CONCLUSIONS. Good diagnostic performance can be obtained with optimized subsets of the standard 24-2 Test pattern that can provide substantial savings in Test times. (Invest Ophthalmol Vis Sci. 2013;54:756‐761) DOI:10.1167/iovs.12-10468
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Monitoring vigilance during perimetry by using pupillography.
Investigative Ophthalmology & Visual Science, 2010Co-Authors: David B. Henson, Thomas EmuhAbstract:PURPOSE. To report and present data on a method for monitoring patient vigilance during a Visual Field Test by using pupillometry. METHODS. Pupil diameter was recorded at 60 Hz with an eye movement tracking system in 13 patients attending the glaucoma outpatient clinics at Manchester Royal Eye Hospital. The patients were instructed to fixate a central target and to press a response button when they saw a stimulus that was randomly presented 5 degrees to the left or right of fixation. A repetitive up/down bracketing strategy was used (1-dB steps, 2-second interstimulus intervals, 10-minute duration) at these two locations. Wavelet analysis was used to extract a denoised measure of the pupil diameter and the amplitude of any pupillary fatigue waves. The relationship between the probability of seeing a stimulus and these two components of the pupil response was investigated. RESULTS. Good pupil data were obtained from 12 patients. Most (8/12) showed gradual miosis and periods of pupillary fatigue waves during the recording session. Pupillary fatigue waves became more evident with Test duration, and the probability of seeing a stimulus was higher when the pupil was dilated (P < 0.001) and the amplitude of the papillary fatigue waves was low (P < 0.001). CONCLUSIONS. Pupil miosis and fatigue wave amplitude are related to vigilance in patients who take a perimetric-type Test. Pupillography can be used to investigate vigilance and how it contributes to perimetric variability.
Cynthia Owsley - One of the best experts on this subject based on the ideXlab platform.
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the driving Visual Field and a history of motor vehicle collision involvement in older drivers a population based examination
Investigative Ophthalmology & Visual Science, 2015Co-Authors: Carrie Huisingh, Gerald Mcgwin, Joanne M Wood, Cynthia OwsleyAbstract:PURPOSE: We designed a Visual Field Test focused on the Field utilized while driving to examine associations between Field impairment and motor vehicle collision involvement in 2,000 drivers ≥70 years old. METHODS: The "driving Visual Field Test" involved measuring light sensitivity for 20 targets in each eye, extending 15° superiorly, 30° inferiorly, 60° temporally and 30° nasally. The target locations were selected on the basis that they fell within the Field region utilized when viewing through the windshield of a vehicle or viewing the dashboard while driving. Monocular Fields were combined into a binocular Field based on the more sensitive point from each eye. Severe impairment in the overall Field or a region was defined as average sensitivity in the lowest quartile of sensitivity. At-fault collision involvement for five years prior to enrollment was obtained from state records. Poisson regression was used to calculate crude and adjusted rate ratios examining the association between Field impairment and at-fault collision involvement. RESULTS: Drivers with severe binocular Field impairment in the overall driving Visual Field had a 40% increased rate of at-fault collision involvement (RR 1.40, 95%CI 1.07-1.83). Impairment in the lower and left Fields was associated with elevated collision rates (RR 1.40 95%CI 1.07-1.82 and RR 1.49, 95%CI 1.15-1.92, respectively), whereas impairment in the upper and right Field regions was not. CONCLUSIONS: Results suggest that older drivers with severe impairment in the lower or left region of the driving Visual Field are more likely to have a history of at-fault collision involvement. Language: en
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the driving Visual Field and a history of motor vehicle collision involvement in older drivers a population based examination
Institute of Health and Biomedical Innovation, 2015Co-Authors: Carrie Huisingh, Gerald Mcgwin, Joanne M Wood, Cynthia OwsleyAbstract:Purpose We designed a Visual Field Test focused on the Field utilized while driving to examine associations between Field impairment and motor vehicle collision involvement in 2,000 drivers ≥70 years old. Methods The "driving Visual Field Test" involved measuring light sensitivity for 20 targets in each eye, extending 15° superiorly, 30° inferiorly, 60° temporally and 30° nasally. The target locations were selected on the basis that they fell within the Field region utilized when viewing through the windshield of a vehicle or viewing the dashboard while driving. Monocular Fields were combined into a binocular Field based on the more sensitive point from each eye. Severe impairment in the overall Field or a region was defined as average sensitivity in the lowest quartile of sensitivity. At-fault collision involvement for five years prior to enrollment was obtained from state records. Poisson regression was used to calculate crude and adjusted rate ratios examining the association between Field impairment and at-fault collision involvement. Results Drivers with severe binocular Field impairment in the overall driving Visual Field had a 40% increased rate of at-fault collision involvement (RR 1.40, 95%CI 1.07-1.83). Impairment in the lower and left Fields was associated with elevated collision rates (RR 1.40 95%CI 1.07-1.82 and RR 1.49, 95%CI 1.15-1.92, respectively), whereas impairment in the upper and right Field regions was not. Conclusions Results suggest that older drivers with severe impairment in the lower or left region of the driving Visual Field are more likely to have a history of at-fault collision involvement.
David F Garwayheath - One of the best experts on this subject based on the ideXlab platform.
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a novel distribution of Visual Field Test points to improve the correlation between structure function measurements
Investigative Ophthalmology & Visual Science, 2012Co-Authors: R Asaoka, David P Crabb, David F Garwayheath, Richard A Russell, Rizwan MalikAbstract:PURPOSE: To create a new Visual Field (VF) Test grid centered at the optic disc (disc-centered Field [DCF]) and to infer the combination of VF Test points (structure-function Field [SFF]), taken from the DCF and the conventional fovea-centered 24-2 grid (24-2) of standard automated perimetry, which yields the strongest sectorial correlation between structure-function measurements of retinal nerve fiber layer (RNFL) thickness and VF sensitivity. METHODS: In 50 eyes with ocular hypertension or open angle glaucoma, the DCF and 24-2 VF were measured with a humphrey Field analyzer II (Full Threshold strategy) and RNFL thickness was measured with Stratus optical coherence tomography. Test points from the DCF and 24-2 VF Were combined and divided into 12 sectors according to the spatial distribution of the RNFL. A novel VF for structure-function studies was established using the following criteria: each sector must contain at least one or two Test points (depending on the sector's location), and the combination of Test points which yields the strongest structure-function correlation is selected. RESULTS: The SFF consisted of 40 Test points. The structure-function correlation for the SFF was compared with the standard 24-2 VF; a multiple-comparison Test for dependent groups was carried out using a percentile bootstrap method, which indicated that the sector correlation coefficients in the SFF were significantly higher than those in the 24-2 VF. CONCLUSIONS: The SFF, with fewer Test locations, has a stronger structure-function correlation than the 24-2 VF. This improved correlation may help clinicians to better interpret functional measurements in relation to structural measurements.
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mapping the Visual Field to the optic disc in normal tension glaucoma eyes
Ophthalmology, 2000Co-Authors: David F Garwayheath, Fred W. Fitzke, Darmalingum Poinoosawmy, Roger A HitchingsAbstract:PURPOSE: To establish the anatomical relationship between Visual Field Test points in the Humphrey 24-2 Test pattern and regions of the optic nerve head (ONH) DESIGN: Cross-sectional study. PARTICIPANTS: Glaucoma patients and suspects from the Normal Tension Glaucoma Clinic at MoorFields Eye Hospital. METHODS: Sixty-nine retinal nerve fiber layer (RNFL) photographs with well-defined RNFL defects and/or prominent bundles were digitized. An appropriately scaled Humphrey 24-2 Visual Field grid and an ONH reference circle, divided into 30 degrees sectors, were generated digitally. These were superimposed onto the RNFL images. The relationship of Visual Field Test points to the circumference of the ONH was estimated by noting the proximity of Test points to RNFL defects and/or prominent bundles. The position of the ONH in relation to the fovea was also noted. MAIN OUTCOME MEASURES: The sector at the ONH corresponding to each Visual Field Test point, the position of the ONH in relation to the fovea, and the effect of the latter on the former. RESULTS: A median 22 (range, 4-58), of a possible 69, ONH positions were assigned to each Visual Field Test point. The standard deviation of estimations was 7.2 degrees. The position of the ONH was 15.5 degrees (standard deviation 0.9 degrees ) nasal and 1.9 degrees (standard deviation 1.0 degrees ) above the fovea. The location of the ONH had a significant effect on the corresponding position at the ONH for 28 of 52 Visual Field Test points. CONCLUSIONS: A clinically useful map that relates Visual Field Test points to regions of the ONH has been produced. The map will aid clinical evaluation of glaucoma patients and suspects, as well as form the basis for investigations of the relationship between retinal light sensitivity and ONH structure.
