RETeval Complete Option
RET
eval
Device User Manual 49
560 cd/m² red light to attenuate the response from the L and M cones and a flash brightness of
1 cd·s/m² at 4.2 Hz. The resulting signal is very small, so a large amount of signal averaging is
required. The long protocol uses 500 averages (120 seconds) matching Yamamoto, Hayashi, and
Takeuchi (1999), while the short protocol uses 250 averages (60 seconds).
The S-cone processing is the same as the 2 Hz ISCEV flash response. The S-cone response occurs
a little after 40 ms. The b-wave cursor will usually not select that peak, rather it will select the
earlier LM-cone response.
On-off (long flash) protocols
On-off protocols (also known as long flash protocols) have an extended-length stimulus in order
to separate the on response from the off response in the ERG. Long flash protocols have been
used for example in patients with retinitis pigmentosa (Cideciyan and Jacobson 1993), congenital
stationary night blindness (Cideciyan and Jacobson 1993, Sustar et al. 2008), cone dystrophy
(Sieving 1994), and enhanced s-cone syndrome (Audo et al. 2008). To better see when the off
response should be, showing the stimulus as a function of time on the reports may be useful.
See Stimulus waveforms on page 11 for how to configure this option.
Two protocols (a short and long test duration) are provided that use a white light stimulus. The
stimulus is a 250 cd/m
2
white light, which has been shown to have a near maximal d-wave (Kondo
et al. 2000), with a 40 cd/m
2
white background to suppress the rod response. Thus, when the
stimulus is on, the luminance is 290 cd/m
2
; and when the stimulus is off, the luminance is
40 cd/m
2
. The on and off times of the stimulus are both about 144.9 ms, which maximizes the
amplitude of the d-wave (Sieving 1993, Sustar, Hawlina, and Brecelj 2006) while keeping the test
duration as short as possible. The short protocol uses 100 averages (taking 30 seconds) and the
long protocol uses 200 averages (taking 60 seconds).
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