elektron eye technology Henson 9000, Manual, Page: 29 / 155

29 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
3 .1 .3 .1 Sin gle Stim u lu s algorith m
The threshold sensitivity is measured at four test locations, one in each quadrant. The
locations are displaced 9 degrees from the vertical and horizontal meridians.
At each location a repetitive bracketing algorithm (1dB steps, six presentations) is
undertaken.
The average intensity of the last four presentations, at each of the four test locations, is
then taken as the threshold. To guard against the inclusion of data from locations
where the threshold is abnormally depressed, the algorithm excludes data from
locations where the average of the last four presentations is below the 95% confidence
limits of the expected age setting. If all test locations are excluded, the threshold is set
at 4dB below the age setting.
Ten demonstration presentations are made prior to the collection of data.
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