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37 Vis ua l field tes ts
E l e k t r o n E y e T e c h n o l o g y 2 0 1 8
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ZATA Thr es ho ld tes t
ZATA (Zippy Adaptive Threshold Algorithm) is a new threshold program that is faster and more
accurate than earlier threshold tests (Full Threshold, Fast Threshold). Shorter test times are
important in perimetry, as patients find it hard to maintain their attention much beyond three
minutes and loss of attention is associated with increased variability.
When possible the ZATA program uses the data from a previous visual field test to seed
starting values. When no prior data is available it starts from age-dependent normal values.
Starting from prior threshold estimates not only makes the test faster but also improves the
accuracy of the threshold estimates.
The ZATA test can use either the 30-2, 24-2 or 10-2 pattern of test stimuli.
Z A T A F ast an d Z A T A Stan dard. ZATA Fast differs from ZATA Standard in that it has looser
terminating criteria. The terminating criteria dictate how accurate the threshold estimate must
be before the program stops testing each location. Looser terminating criteria mean that the
ZATA Fast test will be quicker than ZATA Standard, although the accuracy of each threshold
estimate will be reduced by a small amount. ZATA Fast is appropriate for patients where less
accurate estimates are acceptable. i.e. those with no established loss.
The ZATA program presents one stimulus at a time and the patient responds to each seen
presentation by pressing a
response button.
At the end of the test the results can be viewed in a variety of different ways.
The standard printout includes, threshold values (numeric and gray scale), defect values
(age and pattern related), probability values (age and pattern related) along with a series of
global indices (MD, PSD, Hemifield), test details and patient demographics.
T o get m ore h elp on a test sc reen item c lic k over th e item in th e im age below .
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