Dark adaptation time in canine electroretinography using a contact lens electrode with a built-in light source

Abstract

The purpose of this study was to evaluate the dark adaptation time in canine electroretinography (ERG) using a contact lens electrode with a built-in LED. Twelve eyes of six normal laboratory beagle dogs were used and exposed to steady room light at 500 lux for 30 min for light adaption. ERG was recorded at different time points during dark adaptation in sedated and light-adapted beagles. The stimulus intensity was 0.0096 cd/m2/sec. The b-wave amplitude increased significantly until 25 min of dark adaptation, whereas no significant changes in amplitudes were observed after 30 min. Dark adaptation for more than 25 min would be necessary for accurate ERG in canine ERG using a contact lens electrode with a built-in LED.

Electrophysiological Studies on The Dynamics of Luminance Adaptation in the Mouse Retina

“…In agreement with previous studies in rodents [26,29,33], canines [25] and humans [20], we demonstrated that the implicit times of the flash ERGs decreased during light adaptation as well as during dark adaption. As proposed above for their corresponding amplitudes, the sudden increase after background light onset and subsequent decrease in implicit times over both light/dark adaptation periods is probably also a general recovery after an instantaneous change in implicit time following the alteration in adaptation level.…”

“…Although there are studies that describe the changes in cone or rod ERGs after bleaching of the retina using paired flash stimuli [30,31,32], there are not many data about ERG responsivity changes during dark adaptation that are recorded with single flash ERGs or flicker ERGs. Li et al [33] found an increase in amplitude and a decrease in latency in rodents during dark adaptation, which is similar to the results in the study of Maehara et al [25] in canines.…”

“…In the present study, the effects of adaptation to high light levels and to dark backgrounds were studied in the same session and on an identical group of animals. In comparison to previous studies on either one or the other adaptation type showing a similarly gradual amplitude increase in the flash ERGs during light (rats: [29], mice: [26,35], humans: [20,21,24]) and during dark adaptation (rodents: [33] and canines: [25]), our study demonstrates this to be the result of an instantaneous amplitude decrease upon the increase of background luminance. However, the amplitude increased further after the background illumination was decreased.…”

“…Peachey et al [22,23] found the implicit time of the b-wave to decrease during light adaptation and the implicit time of the flicker ERG to decrease during both light and dark adaptation by about 3 ms. McAnany and Nolan [19] revealed that the implicit time of the ERG to sine-wave modulation also decreased slightly during light adaptation, even though the phase of the first harmonic remained constant. Similarly in canines, Maehara et al [25] found an increase in the b-wave amplitude and a decrease in the b-wave implicit time during dark adaptation. After around 30 min, both parameters reached a plateau and did not change while the animals were further dark adapted.…”

Normal Clinical Electroretinography Parameters of Healthy Pharaoh Hounddogs

“…The determination of normal ERG values is of great importance for clinical practice, considering that there are numerous intrinsic and extrinsic factors influencing the ERG recordings including the age and breeds of the animal (Itoh et al, 2010), the environment and body temperature (Mizota and Adachi-Usami, 2002), pupil diameter, intraocular pressure and eye movement (Marmor et al, 2009;Grozdanic et al, 2010;Nair et al, 2011), electrode type and position (Mentzer et al, 2005), stage of retinal dark adaptation (Maehara et al, 2015), anesthesia technique (Norman et al, 2008;Lin et al, 2009). All of that contribute to interfere with the values obtained from ERG recording; therefore, the investigations aiming to establish a normal range still continue.…”