Chancellery Research - Research Publications

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    Ocular and Systemic Factors Affecting Laser Speckle Flowgraphy Measurements in the Optic Nerve Head
    Turpin, A ; McKendrick, AM (ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2021-01-01)
    PURPOSE: To investigate the ocular and systemic factors related to glaucoma and to be adjusted for interindividual comparison of ocular blood flow measurement results by laser speckle flowgraphy (LSFG) obtained from the optic nerve head (ONH) in normal Japanese individuals. METHODS: A multicenter, prospective cross-sectional study was conducted. The ONH tissue-area and vessel-area mean blur rate (MT and MV) were evaluated using LSFG and ONH structural parameters using planimetric methods. Multivariate linear mixed-effects modeled regression analysis was used to identify the contributing factors to the MT and MV. The explanatory variables were age; gender; smoking history; body mass index; mean arterial pressure (MAP); heart rate; intraocular pressure; axial length (AL); disc, rim, cup, and β-peripapillary atrophy (β-PPA) areas; and central retinal artery and vein equivalents. RESULTS: In total, 195 eyes of 126 healthy individuals with an average age of 48.1 years were included. Multivariate analysis showed that MAP and disc area had a negative (P < 0.001) correlation, whereas β-PPA area had a positive correlation with MT (P = 0.010). Age and AL had a negative correlation (P = 0.001 and P = 0.011, respectively), whereas cup area had a positive correlation (P = 0.012) with MV. CONCLUSIONS: Interindividual comparison of MT or MV must be adjusted for both systemic factors (blood pressure or age) and local ocular factors (AL and disc, cup, or β-PPA area). TRANSLATIONAL RELEVANCE: Our results provided reference data on the LSFG measurement and are important in comparing ocular blood flow between individuals using LSFG.
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    Do Additional Testing Locations Improve the Detection of Macular Perimetric Defects in Glaucoma?
    Montesano, G ; McKendrick, AM ; Turpin, A ; Brusini, P ; Oddone, F ; Fogagnolo, P ; Perdicchi, A ; Johnson, CA ; Lanzetta, P ; Rossetti, LM ; Garway-Heath, DF ; Crabb, DP (ELSEVIER SCIENCE INC, 2021-11-18)
    PURPOSE: To evaluate the ability of additional central testing locations to improve detection of macular visual field (VF) defects in glaucoma. DESIGN: Prospective cross-sectional study. PARTICIPANTS: Four hundred forty healthy people and 499 patients with glaucomatous optic neuropathy (GON) were tested with a fundus tracked perimeter (CMP; CenterVue) using a 24-2 grid with 12 additional macular locations (24-2+). METHODS: Glaucomatous optic neuropathy was identified based on expert evaluation of optic nerve head photographs and OCT scans, independently of the VF. We defined macular defects as locations with measurements outside the 5% and 2% normative limits on total deviation (TD) and pattern deviation (PD) maps within the VF central 10°. Classification was based on the total number of affected macular locations (overall detection) or the largest number of affected macular locations connected in a contiguous cluster (cluster detection). Criteria based on the number of locations and cluster size were used to obtain equivalent specificity between the 24-2 grid and the 24-2+ grids, calculated using false detections in the healthy cohort. Partial areas under the receiver operating characteristic curve (pAUCs) were also compared at specificities of 95% or more. MAIN OUTCOME MEASURES: Matched specificity comparison of the ability to detect glaucomatous macular defects between the 24-2 and 24-2+ grids. RESULTS: At matched specificity, cluster detection identified more macular defects with the 24-2+ grid compared with the 24-2 grid. For example, the mean increase in percentage of detection was 8% (95% confidence interval [CI], 5%-11%) and 10% (95% CI, 7%-13%) for 5% TD and PD maps, respectively, and 5% (95% CI, 2%-7%) and 6% (95% CI, 4%-8%) for the 2% TD and PD maps, respectively. Good agreement was found between the 2 grids. The improvement measured by pAUCs was also significant but generally small. The percentage of eyes with macular defects ranged from about 30% to 50%. Test time for the 24-2+ grid was longer (21% increase) for both cohorts. Between 74% and 98% of defects missed by the 24-2 grid had at least 1 location with sensitivity of < 20 dB. CONCLUSIONS: Visual field examinations with additional macular locations can improve the detection of macular defects in GON modestly without loss of specificity when appropriate criteria are selected.
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    Subjective measurement of the Stiles-Crawford effect with different field sizes
    Nilagiri, VK ; Suheimat, M ; Lambert, AJ ; Turpin, A ; Vohnsen, B ; Atchison, DA (OPTICAL SOC AMER, 2021-08-01)
    The Stiles-Crawford effect of the first kind (SCE) is the phenomenon in which light entering the eye near the center of the pupil appears brighter than light entering near the edge. Previous investigations have found an increase in the directionality (steepness) of the effect as the testing location moves from the center of the visual field to parafoveal positions, but the effect of central field size has not been considered. The influence of field size on the SCE was investigated using a uniaxial Maxwellian system in which stimulus presentation was controlled by an active-matrix liquid crystal display. SCE directionality increased as field size increased from 0.5° to 4.7° diameter, although this was noted in four mild myopes and not in two emmetropes. The change with field size was supported by a geometric optics absorption model.
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    ConTEXT Explorer: a web-based text analysis tool for exploring and visualizing concepts across time
    Yang, Z ; Mikolajczak, G ; Turpin, A (The Open Journal, 2021-12-09)
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    Increased Depth, Reduced Extent, and Sharpened Edges of Visual Field Defects Measured by Compass Fundus Perimeter Compared to Humphrey Field Analyzer
    Liu, P ; Nguyen, BN ; Turpin, A ; McKendrick, AM (ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2021-10-01)
    PURPOSE: The purpose of this study was to compare visual field results of the COMPASS fundus perimeter (CMP) and the Humphrey Field Analyzer (HFA) in the same eyes; to compare structure-function concordance between circumpapillary retinal nerve fiber layer (Cp-RNFL) profiles and the two perimetry results; and to evaluate whether differences between the two results reflect postulated advantages of real-time eye movement compensation during perimetry. METHODS: We retrospectively analyzed 24-2 visual field data measured with CMP and HFA together with Cp-RNFL optical coherence tomography (OCT) scan data from 95 eyes of 65 people with glaucoma. We defined visual field locations with total deviation (TD) less than -5 dB as defective. The CMP and HFA fields were compared on measures of: spatial extent (number of defective locations); depth (TD values); and sharpness of scotomata edges (maximum TD difference between defective locations and their neighbors). Structure-function concordance between Cp-RNFL profile and respective visual field was also compared. RESULTS: Compared to the HFA, scotomata measured by CMP were of reduced spatial extent (mean difference = -3.14 locations, p < 0.001), greater depth (median TD of CMP = -17 dB versus HFA = -13 dB, p = 0.029) and steeper edges (median of maximum TD difference of CMP = 10.6 dB versus HFA = 6 dB, p < 0.001). Structure-function concordance between Cp-RNFL profile and either visual field were comparable despite the reduced scotoma spatial extent measured by CMP. CONCLUSIONS: Glaucomatous visual fields measured by CMP displayed characteristics consistent with expected effects of using real-time eye movement compensation technology compared to the widely used HFA. TRANSLATIONAL RELEVANCE: Glaucomatous visual field defects measured by the CMP are more localized, deeper, and steeper than those of the HFA.
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    Visual Field Progression in Glaucoma: Comparison Between PoPLR and ANSWERS
    Marin-Franch, I ; Artes, PH ; Turpin, A ; Racette, L (ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2021-12-01)
    PURPOSE: It has been suggested that the detection of visual field progression can be improved by modeling statistical properties of the data such as the increasing retest variability and the spatial correlation among visual field locations. We compared a method that models those properties, Analysis with Non-Stationary Weibull Error Regression and Spatial Enhancement (ANSWERS), against a simpler one that does not, Permutation of Pointwise Linear Regression (PoPLR). METHODS: Visual field series from three independent longitudinal studies in patients with glaucoma were used to compare the positive rate of PoPLR and ANSWERS. To estimate the false-positive rate, the same visual field series were randomly re-ordered in time. The first dataset consisted of series of 7 visual fields from 101 eyes, the second consisted of series of 9 visual fields from 150 eyes, and the third consisted of series of more than 9 visual fields (17.5 on average) from 139 eyes. RESULTS: For a statistical significance of 0.05, the false-positive rates for ANSWERS were about 3 times greater than expected at 15%, 17%, and 16%, respectively, whereas for PoPLR they were 7%, 3%, and 6%. After equating the specificities at 0.05 for both models, positive rates for ANSWERS were 16%, 25%, and 38%, whereas for PoPLR they were 12%, 33%, and 49%, or about 5% greater on average (95% confidence interval = -1% to 11%). CONCLUSIONS: Despite being simpler and less computationally demanding, PoPLR was at least as sensitive to deterioration as ANSWERS once the specificities were equated. TRANSLATIONAL RELEVANCE: Close control of false-positive rates is key when visual fields of patients are analyzed for change in both clinical practice and clinical trials.
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    Principles of Melbourne Connect
    Gruba, P ; Turpin, A ( 2021)
    Melbourne Connect is a new initiative partnership between The University of Melbourne and industry groups. It is the centrepiece of a new innovation ecosystem connected to the university. In this paper we outlined the motivation and methods used to define a set of underlying principles for the operation of the innovation ecosystem.
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    Developing a workforce to support research reliant on data and compute
    Turpin, A ; Gruba, P ; Pozanenko, A ; Stupnikov, S ; Thalheim, B ; Mendez, E ; Kiselyova, N (CEUR, 2021-01-01)
    We describe the construction, operation and evaluation of the Melbourne Data Analytics Platform; a group of academics whose mission is to support research requiring non-trivial data analysis or compute at the University of Melbourne.
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    Improving Personalized Structure to Function Mapping From Optic Nerve Head to Visual Field.
    Turpin, A ; McKendrick, AM (Association for Research in Vision and Ophthalmology, 2021-01-08)
    Purpose: Maps are required to relate visual field locations to optic nerve head regions. We compare individualized structure-to-function mapping (CUSTOM-MAP) to a population-derived mapping schema (POP-MAP). Methods: Maps were compared for 118 eyes with glaucomatous field loss, circumpapillary retinal nerve fiber layer (cpRNFL) thickness measured using spectral domain optical coherence tomography (OCT), and two landmarks: the optic nerve head (ONH) position relative to the fovea and the temporal raphe angle. Locations with visual field damage (total deviation < -6 dB) were mapped to 30° ONH sectors centered on the angle given by each mapping schema. The concordance between damaged function and damaged structure was determined per location for various cpRNFL damage probability levels, with the number of concordant locations divided by the total number of damaged field locations providing a concordance ratio per eye. Results: For the strictest concordance criteria (minimum cpRNFL thickness < 1% of normal), CUSTOM-MAP had higher mean concordance ratio than POP-MAP (60.5% c.f. 57.0% paired Wilcoxon, P = 0.005), with CUSTOM-MAP having a higher ratio in 43 eyes and POP-MAP having a higher ratio in 21 eyes. For all cpRNFL probability levels <20% of normal, more locations concorded for CUSTOM-MAP than POP-MAP. Inspection of the spatial patterns of differences revealed that CUSTOM-MAP often performed better in the arcuate regions, whereas POP-MAP had benefits inferior to the macula. Conclusions: Anatomic parameters required for individualized structure-function mapping are readily measured with OCT and can provide improved concordance for some eyes. Translational Relevance: Personalizing structure-function mapping may improve concordance between these measures. We provide a web-based tool for creating customized maps.
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    Effects of Criterion Bias on Perimetric Sensitivity and Response Variability in Glaucoma
    Rubinstein, NJ ; Turpin, A ; Denniss, J ; McKendrick, AM (ASSOC RESEARCH VISION OPHTHALMOLOGY INC, 2021-01-01)
    PURPOSE: The purpose of this study was to isolate and quantify the effects of observer response criterion on perimetric sensitivity, response variability, and maximum response probability. METHODS: Twelve people with glaucoma were tested at three locations in the visual field (age = 47-77 years, mean deviation = -0.61 to -14.54 dB, test location Humphrey field analyzer [HFA] sensitivities = 1 to 30 dB). Frequency of seeing (FoS) curves were measured using a method of constant stimuli with two response paradigms: a "yes-no" paradigm similar to static automated perimetry and a criterion-free two interval forced choice (2IFC) paradigm. Comparison measures of sensitivity, maximum response probability, and response variability were derived from the fitted FoS curves. RESULTS: Sensitivity differences between the tasks varied widely (range = -11.3 dB to 21.6 dB) and did not correlate with visual field sensitivity nor whether the visual field location was in an area of steep sensitivity gradient within the visual field. Due to the wide variation in differences between the methods, there was no significant difference in mean sensitivity between the 2IFC task relative to the yes-no task, but a trend for higher sensitivity (mean = 1.9 dB, SD = 6.0 dB, P = 0.11). Response variability and maximum response probability did not differ between the tasks (P > 0.99 and 0.95, respectively). CONCLUSIONS: Perimetric sensitivity estimates are demonstrably altered by observer response criterion but the effect varies widely and unpredictably, even within a single test. Response bias should be considered a factor in perimetric test variability and when comparing sensitivities to nonperimetric data. TRANSLATIONAL RELEVANCE: The effect of response criterion on perimetric response variability varies widely and unpredictably, even within a single test.