Table of Contents
Advertisement
To the right of the total deviation plots are two additional plots, labeled Pattern Deviation.
These are similar to the total deviation plots, except that here the test results have been
adjusted for any changes in the height of the measured hill of vision caused, for example,
by cataracts or small pupils. Similarly, the software corrects for any patients who are
"supernormal", adjusting the expected hill of vision upward by the appropriate amount
and thereby making the analysis more sensitive to localized scotomas.
Thus, the numeric Pattern Deviation plot shows the deviation in decibels from the age
corrected normal values, adjusted for any shift in overall sensitivity. The pattern deviation
probability plot indicates the statistical significance of the result at each point. Again, the
darker the symbol the more significant the deviation from the normal threshold value.
Shaded Symbols
Statistical Significance
The patient achieved a threshold level in the range that 95% (P
subjects of the same age achieved for the test locations with this shading.
The probability is less than 5% (P<5%) that a normal subject of the same age
would perform at the threshold level that this patient achieved for the test locations
with this shading.
The probability is less than 2% (P<2%) that a normal subject of the same age
would perform at the threshold level that this patient achieved for the test locations
with this shading.
The probability is less than 1% (P<1%) that a normal subject of the same age
would perform at the threshold level that this patient achieved for the test locations
with this shading.
The probability is less than 0.5% (P<0.5%) that a normal subject of the same age
would perform at the threshold level that this patient achieved for the test locations
with this shading. This shading will also occur if the patient failed to respond at the
maximum contrast level of the instrument (0 dB is indicated).
Mean Deviation and Pattern Standard Deviation (MD & PSD) are global statistical indices
calculated from points over the entire visual field for the threshold tests. These indices
reduce the individual threshold scores to a single number to provide overall information
about the entire visual field. The magnitude of the MD & PSD values are directly correlated
to the Humphrey Field Analyzer indices.
Mean Deviation (MD) is the average elevation or depression of the patient's overall
field compared to the normal reference field. If the deviation is significantly outside
the population norms, a "p" value is given. For example, if p < 2%, this means that
fewer than 2% of the normal population shows an MD larger than that found in this
test. A significant MD may indicate that the patient has an overall depression, or that
Humphrey Matrix User Manual
Test Results and Reliability Measures
Table 4-2 Probability Level Classifications
5%) of normal
2660021138935 Rev. F 2015-11
4-5
Advertisement
Table of Contents
