Zeiss Humphrey FDT 710 User Manual page 34

Operation
3-14
Because the FDT Screening N-30-1 (or C-20-1) and N-30-5 (or C-20-5) programs utilize
different baseline normal contrast levels, they also differ in how they flag (shade) test
locations as being outside normal limits. With the N-30-1 (or C-20-1) test, points are
initially flagged when they reach the P<1% probability significance level (i.e. the sensitivity
level which is found less than 1% of the time in the normal population). With the N-30-5
(or C-20-5) test, points are initially flagged when they reach the P<5% probability
significance level (i.e. the sensitivity level which is found less than 5% of the time in the
normal population), and thus there is a greater chance that any point may be deemed
outside normal limits. Therefore, the N-30-5 (or C-20-5) test is slightly more sensitive,
readily identifying more extensive loss. Below is a clinical example that demonstrates this
difference with a comparison between the Screening N-30-1 and N-30-5 programs.
Humphrey FDT User Manual 2660021149532 Rev. B 2015-11