Combining perimetric suprathreshold and threshold procedures to reduce measurement variability in areas of visual field loss

McKendrick, A and Turpin, A 2005, 'Combining perimetric suprathreshold and threshold procedures to reduce measurement variability in areas of visual field loss', Optometry and vision science, vol. 82, no. 1, pp. 43-51.


Document type: Journal Article
Collection: Journal Articles

Title Combining perimetric suprathreshold and threshold procedures to reduce measurement variability in areas of visual field loss
Author(s) McKendrick, A
Turpin, A
Year 2005
Journal name Optometry and vision science
Volume number 82
Issue number 1
Start page 43
End page 51
Total pages 9
Publisher American academy of optometry
Abstract Purpose. Several current perimetric test strategies use information from neighboring test locations to seed the procedure. When this initial estimate is close to the true threshold, the algorithms terminate quickly with low error. However, when neighboring thresholds are dissimilar, seeding procedures in this manner results in poor accuracy and repeatability. This study aims to develop a test procedure that avoids assumptions based on neighboring locations yet terminates with an acceptable number of presentations. We explore the utility of a combined screening and threshold approach. Methods. Our approach [estimation minimizing uncertainty (EMU)] first applies suprathreshold screening and then in those locations that fail the screening, a ZEST procedure commencing with a uniform probability density function (pdf). EMU was compared with full threshold (FT) using computer simulation. Input to the simulation was empirical standard automated perimetry data (FT) from 265 normal subjects and 163 observers with glaucomatous visual field loss. Test performance was assessed using four patient error models designed to represent patients who respond with no errors, typical false-positive errors, typical false-negative errors, and extremely unreliable patients. Results. When patients made typical false-positive errors, EMU required about 20% fewer presentations than FT averaged across the visual field. EMU required a greater number of presentations than FT when false-negative errors were made. The percentage of locations misclassified as either normal (defined as the thresholds greater than the lower 95% confidence limit of age-corrected norms) or abnormal by EMU was lower than for FT.
Subject Clinical Sciences not elsewhere classified
ISSN 1040-5488
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