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4-2
Test Results and Reliability Measures
Screening Tests
All of the Humphrey Matrix visual field FDT screening tests are supra-threshold tests meaning
that they test at specific age-corrected contrast values determined by the normative database
probability levels. Select the probability levels to use for screening for general clinical use to
maximize sensitivity (-5 uses the 5% probability level) or for population based screening to
maximize specificity (-1 uses the 1% probability level). The screening test results consist of
probability plots of the tested locations for each eye and overall reliability measures along
with patient and test information. The test locations indicate the different probability levels
with different patterns, increasing in darkness with decreasing probability level. See
Tests
on page 6-8.
The N-30-5 (or N-30-1) FDT screening test is essentially the same 19-point rapid screening
test performed on the FDT Visual Field Instrument, except that moving the fixation target is
not required with the Humphrey Matrix. The same normative database is used for the N-30
tests in the FDT and Humphrey Matrix Visual Field Instruments so the tests are comparable
between the two instruments. Each test location is assigned one of four probability levels,
depending on the test selected. Each visual field location is tested until the patient
responds, or until all three probability levels are tested. The initial probability level is tested
twice if needed, followed by once at each of the other levels to complete the N-30
screening. As a result, the screening test time will increase for patients with eye disease.
The 24-2-5 (or 24-2-1) FDT screening test is a screening version of the 24-2 full threshold
test. Each test location is assigned one of two probability levels, depending on the test
selected. Each visual field location is tested at a single probability level (pass/fail). Each
visual field location is tested until the patient responds or the location is tested twice at the
initial probability level to complete the 24-2 screening.
Threshold Tests
All the Humphrey Matrix visual field threshold tests are full threshold tests meaning that
they provide quantitative measures of the visual function at each location tested. The
threshold test results consist of a raw threshold plot (dB values), a gray scale plot (pattern
shading), total and pattern deviation plots (dB values), total and pattern deviation
probability plots (pattern shading), MD and PSD global indices (numeric with probability
values), overall reliability measures, along with patient and test information for each eye
tested. The probability plots indicate one of five possible probability levels with different
patterns, increasing in darkness with decreasing probability level. See
Sample Tests
on page 6-8.
The N-30-F FDT full threshold test is essentially the same 19-point full threshold test
performed on the FDT Visual Field Instrument, except that moving the fixation target is not
required and the threshold algorithm has been optimized to reduce test time with the
Humphrey Matrix. The same normative database is used for the N-30 tests in the FDT and
Humphrey Matrix Visual Field Instruments so the tests are comparable between the two
instruments.
Humphrey Matrix User Manual
Sample
Figure 4-1
and
2660021138935 Rev. F 2015-11
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