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USER MANUAL RETEVET™ PORTABLE ERG
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The signal processing for the non-fl icker tests uses the followings steps. A zero-phase 0.3 Hz high-pass fi lter reduces electrode
drift and offset while preserving waveform timing. Measurements from multiple fl ashes are combined to improve the signal
to noise ratio using a trimmed mean to reduce the effect of outliers after removing outlier replicates whose amplitudes
exceed 1 mV. The resulting waveform is then processed using wavelet-based denoising (Ahmadi and Rodrigo 2013) where
wavelets are attenuated based on the signal to noise power between the post-stimulus (signal) and pre-stimulus (noise)
portions of the waveform. Oscillatory potential analysis does not use the wavelet denoising
Ecvo-Based ERG Protocols for Veterinary Use
The RETevet™ device has a series of protocols based on the guidelines for testing dogs (Ekesten et al. 2013). These protocols
all use the acronym ECVO, which stands for European College of Veterinary Ophthalmologists, which were the original basis
for the guidelines.
The protocol ECVO 5-step can be used to assess the functioning of the rod and cone pathways in the retina. Rod function is
assessed with a series of dim fl ashes after a period dark-adaptation (20 minutes is recommended). Next, cone function is
tested after 10 minutes of light adaption. Waiting or examination room ambient light is close to 30 cd/m² which is likely
suffi cient or the built-in 30 cd/m² can be used per each eye. This protocol is recommended for anesthetized or sedated
animals, as the test duration is fairly long.
ECVO 5-step
Description Eye
Flash Luminance Energy
(0.33, 0.33 white)
Background Luminance
(0.33, 0.33 white)
# Flashes
Dark-adaptation timer Both Off Off
Dark-adapted 0.01 Right 0.01 cd·s/m² @ 0.2 Hz Off 4
Dark-adapted 3.0 Right 3 cd·s/m² @ 1 / 15 Hz Off 4
Dark-adapted 10.0 Right 10 cd·s/m² @ 0.05 Hz Off 1
Dark-adapted 0.01 Left 0.01 cd·s/m² @ 0.2 Hz Off 4
Dark-adapted 3.0 Left 3 cd·s/m² @ 1 / 15 Hz Off 4
Dark-adapted 10.0 Left 10 cd·s/m² @ 0.05 Hz Off 1
Light adaptation timer Right Off 30 cd/m²
Light adapted 3.0 Right 3 cd·s/m² @ 2 Hz 30 cd/m² 20
Light adapted 3.0 fl icker Right 3 cd·s/m² @ 28.3 Hz 30 cd/m² 141 – 424
Light adaptation timer Left Off 30 cd/m²
Light adapted 3.0 Left 3 cd·s/m² @ 2 Hz 30 cd/m² 20
Light adapted 3.0 fl icker Left 3 cd·s/m² @ 28.3 Hz 30 cd/m² 141 – 424
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