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The effective dynamic ranges for glaucomatous visual field progression with standard automated perimetry and stimulus sizes III and V
Journal article   Open access   Peer reviewed

The effective dynamic ranges for glaucomatous visual field progression with standard automated perimetry and stimulus sizes III and V

Michael Wall, Gideon K.D Zamba and Paul H Artes
Investigative Ophthalmology and Visual Science, Vol.59(1), pp.439-445
2018
DOI: 10.1167/iovs.17-22390
PMCID: PMC5777662
PMID: 29356822
url
https://doi.org/10.1167/iovs.17-22390View
Published (Version of record) Open Access

Abstract

Purpose: It has been shown that threshold estimates below approximately 20 dB have little effect on the ability to detect visual field progression in glaucoma. We aimed to compare stimulus size V to stimulus size III, in areas of visual damage, to confirm these findings by using (1) a different dataset, (2) different techniques of progression analysis, and (3) an analysis to evaluate the effect of censoring on mean deviation (MD).Methods: In the Iowa Variability in Perimetry Study, 120 glaucoma subjects were tested every 6 months for 4 years with size III SITA Standard and size V Full Threshold. Progression was determined with three complementary techniques: pointwise linear regression (PLR), permutation of PLR, and linear regression of the MD index. All analyses were repeated on "censored'' datasets in which threshold estimates below a given criterion value were set to equal the criterion value.Results: Our analyses confirmed previous observations that threshold estimates below 20 dB contribute much less to visual field progression than estimates above this range. These findings were broadly similar with stimulus sizes III and V.Conclusions: Censoring of threshold values < 20 dB has relatively little impact on the rates of visual field progression in patients with mild to moderate glaucoma. Size V, which has lower retest variability, performs at least as well as size III for longitudinal glaucoma progression analysis and appears to have a larger useful dynamic range owing to the upper sensitivity limit being higher.

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