visualFields (version 0.6.2)

nvsapdefault: SUNY-IU normative reference values for static automated perimetry

Description

Normative reference values or (normative values or nv for short) for static automated perimetry (SAP) obtained from a combination of control subjects from SUNY and IU databases.

Usage

data( nvsapdefault )

Format

This normative-value object is defined by some tables, variables, and sub-structures, some of which are mandatory and some which are not. Importantly an age linear model must be included for test pattern (24-2) and presentation algorithm (e.g. SITA standard). Also important are the tables specifying the settings. Think of the normative-value object as a structure with several levels. The first level has three main substructures with settings:

pmapsettings

mandatory. Information about which percentiles are used for location-wise analysis in this nv and their corresponding color coding for display. This is a table with four columns. First column specifies the percentiles (in percent) for cutoffs and the other three columns are the corresponding RGB values (defined from 0 to 1) specifying the color code to use for values below that percentile

globalco

mandatory. Percentiles to be used for the analysis of globan indices such us mean deviation (MD), pattern standard deviation (PSD) or visual-field index (VFI)

nvname

mandatory. Name assigned to this normative-value object

From here age linear models, percentile values, etc are defined for combination of test patterns and presentation algorithms. It is important that the construction of the name for each of the normative-value for the particular test and presentation is in agreement with the values of tperimetry and talgorithm in vf. This is very important because it is the way visualFields can identify automatically which normative values are to be used with data for a particular visual field. For instance, for the test pattern 24-2 (p24d2) and the stimulus-presentation algorithm SITA standard (sitas), the substructure in the normative-values object must be called p24d2_sitas. This substructure itself is composed of other strutures and tables. These are

demographics

optional. It has stats about the controls subjects used for the calculation of the normative values

agelm

mandatory. A table with two columns, intercept and slope, specifying a linear model modeling the (linear) decrease at each location of the sensitivities in decibels (dB) per year. These were calculated with the ageLinearModel. See locations 26 and 35 have NAs. That is because these are the locations that correspond anatomically with the blind spot (see vfsettings) and are hence excluded from any analysis

sds

mandatory. A table with three columns with the standard deviations for threshold sensitivities, total-deviation values (TD), and pattern-deviation values (PD)

TDpercloc

mandatory. A table with as many columns as cutoff percentiles (rows) were defined in pmapsettings. Each column is the TD cutoff value for each percentile. It is used to get the probability map

PDpercloc

mandatory. A table with as many columns as cutoff percentiles (rows) were defined in pmapsettings. Each column is the PD cutoff value for each percentile. It is used to get the probability map

percglo

mandatory. A table with as many columns as cutoff percentiles (rows) were defined in globalco for global indices. Each row has a different statistical index. Most of them are not really used by convention. The statistical indices considered are mean and standard deviation of the threshold sensitivities (msens and ssens), mean and standard deviation of the TD values (mtdev and stdev), and mean and standard deviation of the PD values (mpdev and spdev). The two indices that are used by convention are mtdev and spdev, that is mean deviation (MD) and pattern standard deviation (PSD)

percvfi

mandatory. A table with as many columns as cutoff percentiles (rows) were defined in globalco for global indices. This table has data only for the VFI (mvfi) and the standard deviation of the VFI at each locaton (svfi)

nvtdrank

optional, but necessary to run bebie with the option diff = TRUE. A table with two columns, mean normal Bebie TD rank curve and the standard deviation at each ranked location.

perctdrank

optional, but necessary to run bebie with the option percentiles = TRUE. A table with as many columns as cutoff percentiles (rows) were defined in pmapsettings. Each column is the TD cutoff value for each percentile

perctdrankadj7

optional, but necessary to run bebie with the option diff = TRUE and percentiles = TRUE. Same as perctdrank but the difference from mean normal Bebie TD rank curve analysis

References

[1] ADD REFERENCE FOR 24-2

[2] H. J. Wyatt, M. W. Dul, and W. H. Swanson. Variability of visual field measurements is correlated with the gradient of visual sensitivity. Vision Research, 47, 2007.

[3] A. Shafi, W. H. Swanson, and M. W. Dul. Structure and Function in Patients with Glaucomatous Defects Near Fixation. Optometry and Vision Science, 88, 2011.