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Michael Wall, K. D. Zamba, Paul H Artes; The Effective Dynamic Ranges for Visual Field Progression with Standard Automated Perimetry with Stimulus Sizes III and V. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2860.
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© ARVO (1962-2015); The Authors (2016-present)
It has been suggested that threshold estimates below about 20 dB (32 cd/m; Weber contrast 3.2) have little effect on the ability to detect visual field progression in glaucoma with Goldmann size III (diameter, 0.43°). Our goals were to confirm these findings in a different dataset, and with different techniques of progression analysis, and to investigate if similar effects are observed with stimulus size V (diameter, 1.7°) which has lower retest variability than size III.
In the Iowa Variability in Perimetry (VIP) Study, 120 glaucoma subjects and 60 normals were tested every six months for 4 years. Progression was determined with three complementary techniques: pointwise linear regression (PLR), Permutation of PLR (PoPLR), and linear regression of the Mean Deviation (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.
Our analyses confirmed previous observations that threshold estimates below 15-25 dB contribute much less to visual field progression than estimates above this range with PoPLR (Figure) or PLR. These findings were broadly similar with stimulus sizes III and V. At high-specificity criteria, tests with stimulus size V revealed relatively more progression than those with stimulus size III.
Censoring of threshold values <15-25 dB has relatively little impact on the rates of visual field progression in glaucoma patients with mild to moderate visual field damage. Size V testing performs at least as well as size III for longitudinal glaucoma progression analysis.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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