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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
6 .1 3 .1 Glau c om a Stagin g Sy stem : GSS II
It is often helpful when reviewing visual field data to have a means to scale the extent of loss.
The Henson 9000 uses the GSS II system developed by Paolo Brusini. It is based upon the Mean
Defect and Pattern Standard Deviation and plots these 2 global measures against each other.
The plot area is divided in to seven regions, Normal, Borderline and 5 stages of loss. Stage 1
being early loss while stage five is advanced loss.
Using both Mean Defect and Pattern Standard Deviation is better than using either index in
isolation. Pattern Standard Deviation is more sensitive than Mean Defect to early localised loss
while Mean Defect is more sensitive when defects become advanced.
The progression software plots each visual field result as a point on a GSS II chart and connects
the points together with a line. The first records point is coloured blue while the last one is
coloured red. Ideally you would like to see all the points clustered together indicating that there
has been very little change. Movement towards the lower right hand corner (towards stage five)
indicates progressive loss.
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