LKC TECHNOLOGIES RETeval - Reference Intervals and Data Interpretation; Understanding Reference Intervals

Reference Intervals
RET eval Device User Manual 67
Reference Intervals
LKC has gathered reference values (CLSI 2008, Davis and Hamilton 2021) in order to establish
corresponding reference intervals. Reference intervals are sometimes referred to as “normal
data” or “normative data”.
If reference data is available for a test and reference data reporting is on (see next section), age-
matched reference data will automatically be displayed by the RET eval device. Please ensure
both the birthdate and the system date on the RET eval device are correct for accurate age-
matching of the reference interval information. ERG results also depend on the electrode type
used. LKC’s reference data was gathered using Sensor Strips and thus will only be shown in that
electrode type is selected. Please ensure the correct electrode type is selected during the test.
Reference intervals can be used to compare an individual patient’s measurements with those
acquired in a normal population. All RET eval reference intervals (except OPs) are one-tailed,
meaning that abnormally slow or small waveforms are colored yellow or red while fast or large
waveforms, even if they are atypically fast or large, are colored green to better match what is
known about how ERG waveforms are affected by disease. For timing, measurements from the
95
th
percentile to the 97.5
th
percentile are colored yellow and above the 97.5
th
are colored red.
For amplitudes (and pupil area ratios), measurements from the 5
th
percentile to the 2.5
th
percentile are colored yellow and measurements smaller than the 2.5
th
percentile are colored
red. Green coloring (or the absence of color on the device UI) is used for the remaining 95% of
the range. If a measurement is smaller than all the reference values, it has a percentile of 0%; if
larger than all the reference values, 100%. The PDF report will also include the reference
distribution percentile for each measurement.
In addition to the color coding and percentile reporting described above, the RET eval device also
displays a rectangular box enclosing the middle 95% of values for most cursor measurements (2-
Reference data
version.
Results faster
than all the
reference
sample have a
percentile of 0%.
Atypically slow
times and small
amplitudes are
suggestive of
disease
“Green” indicates
typical results
for normally-
sighted subjects.
“Yellow” indicates
marginally
atypical for a
subject with
normal vision.
ERGs change with electrode type. LKC reference data is
only for Sensor Strips. If another electrode type is selected,
no reference data will be displayed.