The influence of sampling errors on test-retest variability in Perimetry (2024)

Maddess, T. (2011). The influence of sampling errors on test-retest variability in Perimetry. Investigative Ophthalmology and Visual Science, 52(2), 1014-1022. https://doi.org/10.1167/iovs.10-6014

Maddess, Ted. / The influence of sampling errors on test-retest variability in Perimetry. In: Investigative Ophthalmology and Visual Science. 2011 ; Vol. 52, No. 2. pp. 1014-1022.

@article{4317e8c87a0f41eeac4ef18eb164cd1f,

title = "The influence of sampling errors on test-retest variability in Perimetry",

abstract = "PURPOSE. To determine whether visual fields measured by standard automated perimetry (SAP) can be distorted by higherspatial-frequency image components and, in particular, whether test-retest variability of SAP fields can be explained by the combination of small scale fixational drift, small stimulus size, and coarse spatial sampling of the visual fields. METHODS. Standard SAP test patterns have points 6° apart. The amplitude spectra of the perimeter's 10-2 fields (model 511 Humphrey Field Analyser [HFA]; Carl Zeiss Meditec, Inc., North Ryde, NSW, Australia) were assessed to see whether their finer grained sampling revealed spatial frequencies that could cause distortions of standard fields because of undersampling. Model visual fields were then constructed whose spectra were similar to the 10-2 fields, and test-retest variability was examined for Goldmann sizes III to VI stimuli and Gaussian fixational drift with standard deviations of 0.075° to 0.3°. RESULTS. The 10-2 fields showed significant spatial frequency content up to 0.25 cyc/deg, three times the highest frequency that a 30-2 or 24-2 sample grid can resolve. As reported for SAP, test-retest variability increased with scotoma depth, and increasing the stimulus size from III to VI caused a reduction in test-retest variability, as did reduced fixation jitter. CONCLUSIONS. With fixation drift half the size of that exhibited by good fixators, many of the features of SAP test-retest variability were reproduced. Reducing test-retest variability may therefore involve using large test stimuli that are blurry in appearance and that overlap somewhat when placed on the perimetric test grid. Overlap across the meridians should perhaps be avoided.",

author = "Ted Maddess",

year = "2011",

month = feb,

doi = "10.1167/iovs.10-6014",

language = "English",

volume = "52",

pages = "1014--1022",

journal = "Investigative Ophthalmology and Visual Science",

issn = "0146-0404",

publisher = "Association for Research in Vision and Ophthalmology Inc.",

number = "2",

}

Maddess, T 2011, 'The influence of sampling errors on test-retest variability in Perimetry', Investigative Ophthalmology and Visual Science, vol. 52, no. 2, pp. 1014-1022. https://doi.org/10.1167/iovs.10-6014

The influence of sampling errors on test-retest variability in Perimetry. / Maddess, Ted.
In: Investigative Ophthalmology and Visual Science, Vol. 52, No. 2, 02.2011, p. 1014-1022.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - The influence of sampling errors on test-retest variability in Perimetry

AU - Maddess, Ted

PY - 2011/2

Y1 - 2011/2

N2 - PURPOSE. To determine whether visual fields measured by standard automated perimetry (SAP) can be distorted by higherspatial-frequency image components and, in particular, whether test-retest variability of SAP fields can be explained by the combination of small scale fixational drift, small stimulus size, and coarse spatial sampling of the visual fields. METHODS. Standard SAP test patterns have points 6° apart. The amplitude spectra of the perimeter's 10-2 fields (model 511 Humphrey Field Analyser [HFA]; Carl Zeiss Meditec, Inc., North Ryde, NSW, Australia) were assessed to see whether their finer grained sampling revealed spatial frequencies that could cause distortions of standard fields because of undersampling. Model visual fields were then constructed whose spectra were similar to the 10-2 fields, and test-retest variability was examined for Goldmann sizes III to VI stimuli and Gaussian fixational drift with standard deviations of 0.075° to 0.3°. RESULTS. The 10-2 fields showed significant spatial frequency content up to 0.25 cyc/deg, three times the highest frequency that a 30-2 or 24-2 sample grid can resolve. As reported for SAP, test-retest variability increased with scotoma depth, and increasing the stimulus size from III to VI caused a reduction in test-retest variability, as did reduced fixation jitter. CONCLUSIONS. With fixation drift half the size of that exhibited by good fixators, many of the features of SAP test-retest variability were reproduced. Reducing test-retest variability may therefore involve using large test stimuli that are blurry in appearance and that overlap somewhat when placed on the perimetric test grid. Overlap across the meridians should perhaps be avoided.

AB - PURPOSE. To determine whether visual fields measured by standard automated perimetry (SAP) can be distorted by higherspatial-frequency image components and, in particular, whether test-retest variability of SAP fields can be explained by the combination of small scale fixational drift, small stimulus size, and coarse spatial sampling of the visual fields. METHODS. Standard SAP test patterns have points 6° apart. The amplitude spectra of the perimeter's 10-2 fields (model 511 Humphrey Field Analyser [HFA]; Carl Zeiss Meditec, Inc., North Ryde, NSW, Australia) were assessed to see whether their finer grained sampling revealed spatial frequencies that could cause distortions of standard fields because of undersampling. Model visual fields were then constructed whose spectra were similar to the 10-2 fields, and test-retest variability was examined for Goldmann sizes III to VI stimuli and Gaussian fixational drift with standard deviations of 0.075° to 0.3°. RESULTS. The 10-2 fields showed significant spatial frequency content up to 0.25 cyc/deg, three times the highest frequency that a 30-2 or 24-2 sample grid can resolve. As reported for SAP, test-retest variability increased with scotoma depth, and increasing the stimulus size from III to VI caused a reduction in test-retest variability, as did reduced fixation jitter. CONCLUSIONS. With fixation drift half the size of that exhibited by good fixators, many of the features of SAP test-retest variability were reproduced. Reducing test-retest variability may therefore involve using large test stimuli that are blurry in appearance and that overlap somewhat when placed on the perimetric test grid. Overlap across the meridians should perhaps be avoided.

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U2 - 10.1167/iovs.10-6014

DO - 10.1167/iovs.10-6014

M3 - Article

SN - 0146-0404

VL - 52

SP - 1014

EP - 1022

JO - Investigative Ophthalmology and Visual Science

JF - Investigative Ophthalmology and Visual Science

IS - 2

ER -

Maddess T. The influence of sampling errors on test-retest variability in Perimetry. Investigative Ophthalmology and Visual Science. 2011 Feb;52(2):1014-1022. doi: 10.1167/iovs.10-6014