Figure - available via license: Creative Commons Attribution-NonCommercial 3.0 Unported
Content may be subject to copyright.
Influence of dark-adaptation time on the implicit times of the b-wave in conscious Miniature Schnauzer dogs. a, b, c : A different superscript on the error bars indicates a significant statistical difference (p < 0.05).
Source publication
The optimal dark adaptation time of electroretinograms (ERG's) performed on conscious dogs were determined using a commercially available ERG unit with a contact lens electrode and a built-in light source (LED-electrode). The ERG recordings were performed on nine healthy Miniature Schnauzer dogs. The bilateral ERG's at seven different dark adaptati...
Context in source publication
Context 1
... implicit times of the b-wave significantly increased up to 20 min. Beyond the 20 min of dark adaptation time, the mean b-wave implicit time was 48.60 ± 9.64 msec. However, there were no significant differences after 20 min dark adaptation, and the curve approached a plateau after 20 min of dark adaptation (Figs. 5 & 6). (1,10,20,30,40,50, and 60 min) at a white light intensity of 2.5 cd ․ s/m² in Miniature Schnauzer dogs. The light stimulus is given at the beginning of each recording. A) 1: 1 min of dark adaptation time; 2: 10 min of dark adaptation time; 3: 20 min of dark adaptation time B) 4: 30 min of dark adaptation time; 5: 40 min of dark ...Similar publications
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,...
Psychophysical and electroretinographic (ERG) studies indicate that patients with Stargardt disease exhibit abnormally slow rod dark adaptation after illumination that bleaches a substantial fraction of rhodopsin. However, relatively little information is available concerning rod recovery in this disease after weaker adapting (i.e., conditioning) l...
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.
Conclusions:
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.
... This difference was due to short and long dark adaptation times. As the dark adaptation time increases, the amplitude of ERG waves increases gradually (Yu et al., 2007). ...
Retinal ischemia/reperfusion (I/R) injury is a major cause of vision loss in many ocular diseases. Retinal I/R injury is common in diabetic retinopathy, which as a result of hyperglycemia damages the retina and can cause blindness if left untreated. Inflammation is a major contributing factor in the pathogenesis of I/R injury. α-Melanocyte-stimulating hormone (α-MSH) is an anti-inflammatory peptide hormone that has displayed protective effects against I/R-induced organ damages. Here, we aimed to investigate the protective role of α-MSH on I/R-induced diabetic retinal damage using hyperglycemic C57BL/6J Ins2Akita/+ mice. Experimental I/R injury was induced by blocking the right middle cerebral artery (MCA) for 2 h followed by 2 h or 22 h of reperfusion using the intraluminal method. Since ophthalmic artery originates proximal to the origin of the MCA, the filament also blocked blood supply to the retina. Upon treatment with α-MSH at 1 h after ischemia and 1 h after reperfusion, animals displayed significant improvement in amplitudes of b-wave and oscillatory potentials during electroretinography. α-MSH also prevented I/R-induced histological alterations and inhibited the development of retinal swelling. Loss of retinal ganglion cells as well as oxidative stress were significantly attenuated in the α-MSH-treated retinae. Level of interleukin 10 was significantly increased after α-MSH treatment. Moreover, gene expression of glutamate aspartate transporter 1, monocarboxylate transporter (MCT) 1 and MCT-2 were significantly higher after α-MSH administration. In conclusion, α-MSH mitigates the severity of I/R-induced retinal damage under hyperglycemic condition. These beneficial effects of α-MSH may have important therapeutic implications against retinal I/R injury under hyperglycemic condition.
... 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.
... The standard of normal value in human was established according to the recommendation of ISCEV, and the effect of age and gender on ERG response was studied (2,5,7,12). In veterinary medicine, although there were reports on ERG values in healthy dogs (6,8,9,11,16,17,19,22), the effects of diverse variables on ERG values including breed, age, gender, and other physical factors need to be further clarified. ...
The purpose of this study was to identify the effect of age and gender on the value of electroretinogram (ERG) in healthy dogs. The ERG responses of 68 eyes of 34 dogs (22 males, 12 females) were recorded following the diagnostic protocol for dogs recommended by International Society for Clinical Electrophysiology of Vision under general anesthesia using medetomidine and tiletamine-zolazepam combination. There were significant differences in the implicit time of a-wave of Hi-int R & C response among age groups (P < 0.05) and in the implicit time of a-wave of cone response between male and female (P < 0.05). The rest ERG responses seem to be not affected by age and gender of healthy dogs.
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.
Visual evoked potentials (VEP) and electroretinography (ERG) are known as objective and quantitative methods to analyse the functionality of visual pathways. Separately used in the ophthalmologic clinic to evaluate retina (ERG) or central visual pathways (VEP), this study designs a combined protocol with both techniques recorded in one session, and also proposes a normal data base for beagle. Twelve beagle dogs were used to design a 90-minutes protocol by using a mydriatic drug, anaesthetic protocol and a proper electrode placement. Flash stimulation technique was selected, and monocular stimulations were recorded. A large number of parameters regarding light stimulation, recording, amplification, and signal averaging were also controlled. The sequence of testing was: VEP, ERG scotopic and ERG photopic. Dogs were dark-adapted for at least 20 minutes to record VEP and scotopic ERG, and evaluated in a darkened room. Photopic ERG was tested with a prior 10 minutes light-adaptation, in an illuminated room. Characteristic waveforms were obtained. Four peaks were present and named as: P1, N1, P2, and N2 for VEP recordings. However, in ERG recordings, typical a-wave and b-wave were registered, but c-wave was not present. The proposed electrodiagnostic combined protocol in this study allows the assessment of the visual pathway integrity from retina to visual cortex in dogs. This procedure allows to collect the information in the most simple, shorter and less stressful manner for the patient.
In this study, the electroretinography (ERG) results which are obtained from a total of 40 eyes in 20 Turkish shepherd dogs (TSDs) which meet the standards of ISCEV were evaluated. Accordingly, amplitute of the a-wave 1.298±0.208 microvolt, amplitute of the b-wave 7.670±0.846 microvolt, implicit time of the a-wave 70.268±11.840 milisecond, implicit time of the b-wave 97.072±12.696 milisecond were determined. There is no clinical, funduscopic or ERG evidence of a genetic retina disorder in TSDs. The funduscopic and ERG datas which obtained from 10 patient in different breed which have single-or double sidedblindness revealed that the results of our study can be used as a reference value in further studies about retina in TSDs.
Los potenciales evocados visuales (PEV) y la electrorretinografía (ERG) son dos métodos de análisis objetivo y cuantitativo de la funcionalidad de las vías visuales, que se realizan de forma independiente en la clínica oftalmológica para la evaluación de la retina o de las vías visuales centrales, respectivamente. El presente trabajo propone un protocolo clínico combinado de ambas técnicas en una única sesión, además de una base de datos normales para la raza beagle. Se emplearon 12 beagles para diseñar un protocolo de 90 minutos de duración que incluía el uso de midriáticos, protocolo anestésico y colocación apropiada de electrodos de registro. La técnica de estimulación luminosa seleccionada fueron flashes de luz blanca emitidos de modo monocular. Diversos parámetros de estimulación, registro, amplificación y filtrado fueron calibrados. La secuencia de estimulación fue: PEV, ERG escotópico y ERG fotópico. Las 2 primeras técnicas se realizaron en oscuridad con previa adaptación ocular de 20 minutos, mientras que la última se realizó con luminosidad ambiente y previa adaptación a la luz de 10 minutos. La gráfica de PEV mostró 4 picos (P1, N1, P2, N2), mientras que el ERG mostró las típicas ondas (a y b) sin presencia de onda-c. Este procedimiento permite recoger los registros de ambas pruebas electrodiagnósticas de la manera más simple y menos estresante para el paciente canino, y propone una base de datos normales actualizada para el beagle.
To determine the effects of a standardized intravenous dose of an alpha-2 agonist (Domitor, Orion Pharma, distributed by Pfizer Animal Health, Exton, PA) on the electroretinogram (ERG) response in normal dogs.
Twenty-five normal dogs were used to collect ERG responses including a- and b-wave implicit times (IT) and amplitudes (AMP) before and after administration of medetomidine. Dogs were dark adapted for 20 min and ERGs were obtained using the HMsERG (RetVetCorp Inc., Columbia, MO). The QuickRetCheck protocol (Narfström) was employed to provide the following flash intensities: 10 mcd s/m(2), 3 cd s/m(2), and 10 cd s/m(2). ERGs were repeated after 375 microg/m(2) of medetomidine intravenously. Statistical analysis of the difference between the responses before and after medetomidine at all flash intensities was performed using a mixed effects model for anova.
The P value for the effect of medetomidine on each of the ERG responses was < 0.01. The estimates of the effect of medetomidine were (+)1.35 ms, (-)23 microV, (+)3.16 ms, and (-)47 microV for the a-wave IT, a-wave AMP, b-wave IT, and the b-wave AMP, respectively.
Medetomidine significantly prolongs the implicit time and lowers the amplitude response of both the a- and b-waves in normal dogs at all flash intensities examined. Clinically, however, medetomidine only minimally affects the retinal responses and is a viable choice for use in dog ERGs.
