Fig 1 - uploaded by Shin Ae Park
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Representative waveforms of ERG recording in conscious Miniature Schnauzers. N: onset of the stimulus. a: trough of a-wave. b: peak of b-wave. 1: stimulus intensity 0.025 cd⋅s/m 2. 2: 0.079 cd⋅s/m 2. 3: 0.25 cd⋅s/m 2. 4: 0.79 cd⋅s/ m 2. 5: 2.5 cd⋅s/m 2. 6: 7.9 cd⋅s/m 2. Calibration; horizontal 25 ms, vertical 250 µV.
Source publication
The aim of this study was to determine the most effective light intensity for flash electroretinogram (ERG) examination in conscious dogs using ERG equipment with a contact lens electrode with a built-in LED light source. ERG was performed on the bilateral eyes of ten clinically healthy Miniature Schnauzers at 6 different intensities (0.025, 0.079,...
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Citations
... There is one ERG device which has a contact lens electrode with the light emitting diode (LED) incorporated into the eyepiece. This electrode, called Koijman electrode, has been widely evaluated and used in dogs [31][32][33][34], but not in horses. The Koijman electrode is very light and has the additional advantage of keeping a constant distance between the flash and the retinal surface. ...
Background:
In modern times, horses are utilized not only for labour and transportation purposes but also for recreational activities such as competition and pleasure riding. In these various pursuits, the role of vision plays a crucial role. Electroretinography is the most used test to diagnose diseases of the retinal outer segment. There is a wide variety of devices to perform the electroretinography differing one from each other in the corneal electrode and the light stimulation. The Koijman electrode has been tested in dogs but not in horses. The main purpose of this study was to compare electroretinography parameters from horses sedated with detomidine alone or in combination with butorphanol, during a standardized protocol using the Koijman electrode and RETI-port® system. Seven mares were allocated to the detomidine and detomidine plus butorphanol group in a randomised, controlled, crossover study. Friedman and Willcoxon-signed ranked tests were used to compare the electroretinogram parameters. A Student's t-test was used to compare differences in the number of artefacts to valid values ratio obtained under both sedation protocols.
Results:
Dark adaptation peaked after 16 min under scotopic conditions in both groups. No significant differences in electroretinogram parameters between groups were observed. During the mixed rod and cone response evaluation under scotopic conditions, all mares made a movement of the head resulting in a high number of artefacts. The detomidine plus butorphanol group showed a non-significant tendency to have fewer artefacts and a longer duration of sedation compared to the detomidine group.
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Detomidine alone or combined with butorphanol may be suitable to use Koijman electrode and the RETI-port® to perform a standardized long protocol in horses with some adaptations.
... We evaluated a simple, easy to build and inexpensive experimental setup that includes contact lens electrodes with a built-in white light-emitting diode (LED) light source for ERG recording in rats. This type of electrode has been used in humans (Suzuki et al 1998, Tsuruoka et al 2004, dogs (Kim et al 2008, Yu et al 2007, Sasaki et al 2006, Maehara et al 2005, quail (Endo et al 2008) and rabbits (Maia et al 2004). There are four reports in the literature that describe its use in rats, but with a different ERG setup (Goto et al 2002, Grozdanic et al 2003, Yoneda et al 2003, Yamashita et al 2009. ...
Electroretinography (ERG) is widely used in clinical work and research to assess the retinal function. We evaluated an easy to build ERG setup adapted for small animals comprising two contact lens electrodes with a built-in light-emitting diode and a custom-made amplification system. The system's sensitivity was tested by monitoring ERG in albino rat eyes subjected to mild ischemia. Flash ERG was recorded by two contact lens electrodes positioned on the rat's corneas and used alternately as test or reference. The a- and b-wave amplitudes, a-wave latency, b-wave implicit time and oscillatory potentials (OPs) were analyzed. Ischemia was achieved by elevating the intraocular pressure in the eye's anterior chamber. ERG was recorded on post-ischemia (PI) days -1, 1, 3 and 7. Morphological changes were analyzed on hematoxylin/eosin stained 5 µm sections of control 7d PI retinas. In control eyes, ERG exhibited a pattern similar to a standard recording. Retinas subjected to mild ischemia preserved ordered layered morphology, exhibiting approximately 30% loss of ganglion cells and no changes in gross morphology. By day 3 PI, ischemia caused an increase in the a-wave amplitude (from 34.9 ± 2.7 to 45.4 ± 4.3 µV), a decrease in the b-wave amplitude (from 248 ± 13 to 162 ± 8 µV), an increase in a-wave latency (from 11.1 ± 0.3 to 17.3 ± 1.4 ms) and b-wave implicit time (from 81.0 ± 1.6 to 90.0 ± 2.5 ms), and attenuation of OPs. The described setup proved sensitive and reliable for evaluating subtle changes in the retinal function in small animals.
... For this purpose the so called Ganzfeld (or 'full-field') stimulator was developed and now recommended for use in both humans and animals [22,25]. A contact lens electrode with a built-in LED together with a recording system, have been used in human and animal ERG studies during the past years [10,12,20]. These previous studies employed a similar type of light stimulator (a contact lens active electrode with built-in LEDs stimulator), which is the type used for the ERG equipment (RETIport, Roland Consult, Brandenburg, Germany) in the present study. ...
The purpose of the study was to compare two different electroretinography (ERG) instruments used on the same animal in a laboratory setting. Retinal function in both eyes of 12 healthy miniature schnauzers was evaluated under general anesthesia. Scotopic and photopic ERGs were recorded by the HMsERG and the RETIport using the Dog Standard Protocol recommended by the European College of Veterinary Ophthalmologists (ECVO). The waveforms of the ERGs obtained by the two ERG units were similar to those described in previous studies. The 90% reference ranges using the multiple of medians (MoM) showed that the changes in ERG parameters obtained by the HMsERG unit were very similar to those of the RETIport for most ERG responses, except for a few. The results demonstrate that the two ERG systems are comparable for evaluating retinal function in dogs. Further, the results also show that it is necessary to establish ERG system-specific limits of normality in each laboratory or clinic in order to obtain a correct diagnosis, for example by using a graphical representation of the 90% reference range.
Background
Nowadays in addition to work and transport, horses are also used for competition and pleasure riding purposes. For all these activities vision has a critical role. Electroretinography is the most used test to diagnose diseases of the retinal outer segment. There is a wide variety of devices to perform the electroretinography being the main differences in the corneal electrode and the light stimulation. The Koijman electrode has been tested in dogs but not in horses. The main purpose of this study was to compare electroretinography parameters from horses sedated with detomidine alone or in combination with butorphanol, during a standardized protocol using the Koijman electrode and RETI-port® system. Seven mares, were allocated to the detomidine (D) and detomidine-butorphanol (DB) group in a randomised, controlled, crossover study. Friedman's and Willcoxon-signed ranked tests were used to compare the electroretinogram (ERG) parameters. A Student t-test was used to compare differences in the number of artefacts and valid values obtained under both sedation protocols.
Results
Dark adaptation peaked at 16 minutes in both groups. No significant differences in ERG parameters between both groups were observed. During the mixed rod and cone response evaluation under scotopic conditions, most mares made a movement of the head resulting in a high number of artefacts. The DB group showed a non-significant tendency to have fewer artefacts and a longer duration of sedation compared to the D group.
Conclusions
The Koijman electrode and the RETI-port® can be used to perform a standardized long protocol in horses with some adaptations.
