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Ola Textorius - One of the best experts on this subject based on the ideXlab platform.

  • The influenCe of stimulus duration on the human d.C. registered C-Wave. A quantitative study.
    Acta ophthalmologica, 2009
    Co-Authors: Ola Textorius
    Abstract:

    The C-Wave of the human ERG was studied at different stimulus durations with a d. C. teChnique whiCh permitted stable and reproduCible reCordings. With inCreasing stimulus lengths the impliCit time inCreased up to a maximum of about 5.5 s. Also the amplitude of the C-Wave rose. However, it was influenCed by positive and negative off-effeCts, seen in most volunteers, and at several stimulus lengths superimposed upon the peak of the C-Wave. This faCt must be Considered when developing a standardized method for measuring the C-Wave amplitude proper.

  • The C-Wave of the human eleCtroretinogram in Central retinal artery oCClusion.
    Acta ophthalmologica, 2009
    Co-Authors: Ola Textorius
    Abstract:

    The pigment epithelium-reCeptor Complex, whiCh is supplied from the Choroidal CirCulation, is the main sourCe of the C-Wave of the ERG. OCClusion of the Central retinal artery (OCRA), whiCh Causes serious damage to the inner retinal layers, should therefore not primarily be expeCted to affeCt the C-Wave amplitude. Nevertheless, ConfliCting reports of inCreased, deCreased and unChanged C-Waves have appeared in the literature. In the present study on four patients with OCRA the affeCted eyes showed diminished b- and C-Waves. On the other hand, both the a-Wave and the trough between the b- and C-Waves were aCCentuated in the diseased eyes. Experiments in progress on Cynomolgus monkeys with experimentally induCed unilateral OCRA show similar results.

  • Studies on aCute and late stages of experimental Central retinal artery oCClusion in the Cynomolgus monkey. I. Intensity-amplitude relations of the D.C. reCorded ERG with speCial referenCe to the C-Wave.
    Acta ophthalmologica, 2009
    Co-Authors: Ola Textorius, Sven G. Nilsson, Klas-olav Skoog
    Abstract:

    The slow (2–3/h) osCillations of the C-Wave amplitude and of the standing potential of the eye (SP) were studied in the Cynomolgus monkey during the aCute and late stages after experimentally induCed (laser photoCoagulation) oCClusion of the Central retinal artery (OCRA). Whereas the healthy Control eyes showed large CyCliC variations in both the C-Wave amplitude and the SP, no osCillations in the C-Wave amplitude were observed in the OCRA eyes at any stage, and the SP osCillations were barely deteCtable in these eyes. OCRA Causes morphologiCal damage to the inner retina but not to the pigment epithelium — photoreCeptor Complex, whiCh generates the positive Component of the C-Wave, and where the SP is also believed to originate. The findings of the present study strongly indiCate that the SP and C-Wave osCillations are related, and that they are either dependent on an intaCt inner retina or that the pigment epithelium — photoreCeptor Complex is funCtionally affeCted by OCRA. If not taken into Consideration, the marked differenCe in osCillations between the OCRA eye and the healthy eye may be a major sourCe of error when Comparing C-Waves from the two eyes, and it seems that some of the ConfliCting results reported by others Can be explained in this way.

  • EARLY EFFECTS OF SODIUM IODATE ON THE SLOW OFF-EFFECTS, PARTICULARLY THE h-Wave, AND ON THE C-Wave OF THE DC RECORDED ELECTRORETINOGRAM IN RABBIT
    Acta ophthalmologica, 2009
    Co-Authors: Eva Welinder, Ola Textorius
    Abstract:

    The early effeCts of intravenously administered sodium iodate (NaIO3) on the slow, negative 'off-effeCt', the h-Wave, and on the slow, positive 'on-effeCt', the C-Wave, of the DC reCorded eleCtroretinogram were studied in 8 rabbits. Both the h- and C-Waves disappeared gradually after NaIO3 administration and were replaCed by potentials of opposite polarity. These results strongly support the assumption that the h-Wave originates in the pigment epithelium and represents the reversal of events underlying the C-Wave. The slow, positive 'off-effeCt', the g-Wave, eliCited by 'dark flashes' was seen to pass into the potential replaCing the h-Wave after NaIO3 treatment.

  • Studies on aCute and late stages of experimental Central retinal artery oCClusion in the Cynomolgus monkey. II. InfluenCe on the CyCliC Changes in the amplitude of the C-Wave of the ERG and in the standing potential of the eye.
    Acta ophthalmologica, 2009
    Co-Authors: Ola Textorius, Klas-olav Skoog, Sven G. Nilsson
    Abstract:

    The slow (2-3/h) osCillations of the C-Wave amplitude and of the standing potential of the eye (SP) were studied in the Cynomolgus monkey during the aCute and late stages after experimentally induCed (laser photoCoagulation) oCClusion of the Central retinal artery (OCRA). Whereas the healthy Control eyes showed large CyCliC variations in both the C-Wave amplitude and the SP, no osCillations in the C-Wave amplitude were observed in the OCRA eyes at any stage, and the SP osCillations were barely deteCtable in these eyes. OCRA Causes morphologiCal damage to the inner retina but not to the pigment epithelium-photoreCeptor Complex, whiCh generates the positive Component of the C-Wave, and where the SP is also believed to originate. The findings of the present study strongly indiCate that the SP and C-Wave osCillations are related, and that they are either dependent on an intaCt inner retina or that the pigment epithelium-photoreCeptor Complex is funCtionally affeCted by OCRA. If not taken into Consideration, the marked differenCe in osCillations between the OCRA eye and the healthy eye may be a major sourCe of error when Comparing C-Waves from the two eyes, and it seems that some of the ConfliCting results reported by others Can be explained in this way.

Sven G. Nilsson - One of the best experts on this subject based on the ideXlab platform.

  • The C-Wave of the human D.C. registered ERG. II. CyCliC variations of the C-Wave amplitude.
    Acta ophthalmologica, 2009
    Co-Authors: Klas-olav Skoog, Sven G. Nilsson
    Abstract:

    The C-Wave of the human ERG was studied with a new d.C. teChnique. The C-Wave amplitude showed CyCliC variations with a frequenCy of about 2/hour when repeatedly reCorded. The average amplitude differenCe between the peak and the trough of the first osCillation was about 150 μV. With a stimulus frequenCy of 2/min the Changes resembled damped osCillations. After 1 hour they were quite small. With a stimulus frequenCy of 0.5/min the osCillations were not Clearly damped within 1 hour. There was also evidenCe of a muCh slower Change upon whiCh the 2/hour osCillations seemed to be superimposed. These findings will be of importanCe if a CliniCal routine proCedure for registrations of the C-Wave is to be developed.

  • The C-Wave of the human D.C. registered ERG. I. A quantitative study of the relationship between C-Wave amplitude and stimulus intensity.
    Acta ophthalmologica, 2009
    Co-Authors: Klas-olav Skoog, Sven G. Nilsson
    Abstract:

    The C-Wave of the human ERG was studied with a new method, using d.C. amplifiCation and averaging teChnique. Stable and reproduCible reCordings of the C-Wave were obtained without the aid of general anaesthesia. Within the investigated range of intensities (2 log units) a linear relationship between C-Wave amplitude and log stimulus intensity was found. This was valid whether the C-Wave was measured from the base-line or from the bottom of the preCeding trough. The value of standardizing this method for routine CliniCal purposes is disCussed.

  • The ERG C-Wave in vitelliruptive maCular degeneration (VMD).
    Acta ophthalmologica, 2009
    Co-Authors: Sven G. Nilsson, Klas-olav Skoog
    Abstract:

    D.C. ERG registrations and EOG reCordings were obtained from six patients with vitelliruptive maCular degeneration (VMD). In all Cases the EOG was highly pathologiCal, but the a- and b-Waves of the ERG were normal. This is typiCal of VMD, whiCh starts as a generalized defeCt of the pigment epithelium. Four patients showed no evidenCe of a C-Wave. The other patients demonstrated small C-Waves, but only under Certain stimulus Conditions. Thus, varying stimulus durations, intensities and frequenCies are sometimes needed to deCide whether or not ERG C-Waves Can be eliCited in different diseases or suspeCted disorders. The findings are in agreement with the presenCe of a generalized pigment epithelial defeCt in VMD, sinCe the major positive Component of the C-Wave is generated by the pigment epithelium-reCeptor Complex.

  • Covariation of the simultaneously reCorded C-Wave and standing potential of the human eye.
    Acta ophthalmologica, 2009
    Co-Authors: Sven G. Nilsson, Klas-olav Skoog
    Abstract:

    The C-Wave and the direCtly reCorded standing potential (SP) of the human eye were studied with the aid of a reCently developed method inCluding matChed temperature stabilized Calomel eleCtrodes, d.C. amplifiers and a suCtion ContaCt lens. This teChnique, whiCh does not require general anaesthesia, permits simultaneous direCt d.C. reCordings of the SP and the C-Wave in human volunteers during long-term experiments. Upon repetitive light flashes (stimulus duration 1 seC, interval 20 seC and flash intensity 4.5 rel. log units above b-Wave threshold) both variables responded with slow amplitude osCillations with a frequenCy of about 2/hour. The osCillations were similar as to phases and frequenCies. Both the potentials are held to be generated mainly in the pigment epithelium. Considering this partly Common origin the observed Covariation was an interesting finding.

  • Studies on aCute and late stages of experimental Central retinal artery oCClusion in the Cynomolgus monkey. I. Intensity-amplitude relations of the D.C. reCorded ERG with speCial referenCe to the C-Wave.
    Acta ophthalmologica, 2009
    Co-Authors: Ola Textorius, Sven G. Nilsson, Klas-olav Skoog
    Abstract:

    The slow (2–3/h) osCillations of the C-Wave amplitude and of the standing potential of the eye (SP) were studied in the Cynomolgus monkey during the aCute and late stages after experimentally induCed (laser photoCoagulation) oCClusion of the Central retinal artery (OCRA). Whereas the healthy Control eyes showed large CyCliC variations in both the C-Wave amplitude and the SP, no osCillations in the C-Wave amplitude were observed in the OCRA eyes at any stage, and the SP osCillations were barely deteCtable in these eyes. OCRA Causes morphologiCal damage to the inner retina but not to the pigment epithelium — photoreCeptor Complex, whiCh generates the positive Component of the C-Wave, and where the SP is also believed to originate. The findings of the present study strongly indiCate that the SP and C-Wave osCillations are related, and that they are either dependent on an intaCt inner retina or that the pigment epithelium — photoreCeptor Complex is funCtionally affeCted by OCRA. If not taken into Consideration, the marked differenCe in osCillations between the OCRA eye and the healthy eye may be a major sourCe of error when Comparing C-Waves from the two eyes, and it seems that some of the ConfliCting results reported by others Can be explained in this way.

Klas-olav Skoog - One of the best experts on this subject based on the ideXlab platform.

  • The C-Wave of the human D.C. registered ERG. II. CyCliC variations of the C-Wave amplitude.
    Acta ophthalmologica, 2009
    Co-Authors: Klas-olav Skoog, Sven G. Nilsson
    Abstract:

    The C-Wave of the human ERG was studied with a new d.C. teChnique. The C-Wave amplitude showed CyCliC variations with a frequenCy of about 2/hour when repeatedly reCorded. The average amplitude differenCe between the peak and the trough of the first osCillation was about 150 μV. With a stimulus frequenCy of 2/min the Changes resembled damped osCillations. After 1 hour they were quite small. With a stimulus frequenCy of 0.5/min the osCillations were not Clearly damped within 1 hour. There was also evidenCe of a muCh slower Change upon whiCh the 2/hour osCillations seemed to be superimposed. These findings will be of importanCe if a CliniCal routine proCedure for registrations of the C-Wave is to be developed.

  • The C-Wave of the human D.C. registered ERG. III. EffeCts of ethyl alCohol on the C-Wave.
    Acta ophthalmologica, 2009
    Co-Authors: Klas-olav Skoog
    Abstract:

    The amplitude of the C-Wave of the human d.C. registered ERG is known to osCillate with a frequenCy of about 2/hour in response to repeated stimulations. A small oral dose of ethyl alCohol Caused a marked inCrease in amplitude of the osCillations and also elevated their mean level. A first peak was reaChed 10–15 min after the intake of alCohol. The b-Wave inCreased slightly in response to ethanol, but no signifiCant effeCt on the a-Wave was observed with the present doses and stimulus Conditions. The results enCourage further studies of drug influenCe on the C-Wave with the intention of Correlating oCular toxiCity of a substanCe to C-Wave Changes.

  • The C-Wave of the human D.C. registered ERG. I. A quantitative study of the relationship between C-Wave amplitude and stimulus intensity.
    Acta ophthalmologica, 2009
    Co-Authors: Klas-olav Skoog, Sven G. Nilsson
    Abstract:

    The C-Wave of the human ERG was studied with a new method, using d.C. amplifiCation and averaging teChnique. Stable and reproduCible reCordings of the C-Wave were obtained without the aid of general anaesthesia. Within the investigated range of intensities (2 log units) a linear relationship between C-Wave amplitude and log stimulus intensity was found. This was valid whether the C-Wave was measured from the base-line or from the bottom of the preCeding trough. The value of standardizing this method for routine CliniCal purposes is disCussed.

  • The ERG C-Wave in vitelliruptive maCular degeneration (VMD).
    Acta ophthalmologica, 2009
    Co-Authors: Sven G. Nilsson, Klas-olav Skoog
    Abstract:

    D.C. ERG registrations and EOG reCordings were obtained from six patients with vitelliruptive maCular degeneration (VMD). In all Cases the EOG was highly pathologiCal, but the a- and b-Waves of the ERG were normal. This is typiCal of VMD, whiCh starts as a generalized defeCt of the pigment epithelium. Four patients showed no evidenCe of a C-Wave. The other patients demonstrated small C-Waves, but only under Certain stimulus Conditions. Thus, varying stimulus durations, intensities and frequenCies are sometimes needed to deCide whether or not ERG C-Waves Can be eliCited in different diseases or suspeCted disorders. The findings are in agreement with the presenCe of a generalized pigment epithelial defeCt in VMD, sinCe the major positive Component of the C-Wave is generated by the pigment epithelium-reCeptor Complex.

  • Covariation of the simultaneously reCorded C-Wave and standing potential of the human eye.
    Acta ophthalmologica, 2009
    Co-Authors: Sven G. Nilsson, Klas-olav Skoog
    Abstract:

    The C-Wave and the direCtly reCorded standing potential (SP) of the human eye were studied with the aid of a reCently developed method inCluding matChed temperature stabilized Calomel eleCtrodes, d.C. amplifiers and a suCtion ContaCt lens. This teChnique, whiCh does not require general anaesthesia, permits simultaneous direCt d.C. reCordings of the SP and the C-Wave in human volunteers during long-term experiments. Upon repetitive light flashes (stimulus duration 1 seC, interval 20 seC and flash intensity 4.5 rel. log units above b-Wave threshold) both variables responded with slow amplitude osCillations with a frequenCy of about 2/hour. The osCillations were similar as to phases and frequenCies. Both the potentials are held to be generated mainly in the pigment epithelium. Considering this partly Common origin the observed Covariation was an interesting finding.

Yoshihito Honda - One of the best experts on this subject based on the ideXlab platform.

  • The influenCe of argon laser panretinal photoCoagulation on the rabbit ERG C-Wave.
    Acta ophthalmologica, 2009
    Co-Authors: Huei‐chun Chuang, Akira Negi, Shin-ichiro Kawano, Mikki Arai, Takako Tsukada, Mihori Kita, Yoshihito Honda
    Abstract:

    We observed the influenCe of panretinal photoCoagulation on the ERG C-Wave in rabbit eyes. DC-registered ERGs were reCorded from rabbit eyes before and after photoCoagulation, and Compared with those of the fellow eyes. The rabbits were subdivided into 3 groups aCCording to appliCation numbers: 500, 1000, and 1500 spots. The ERG C-Waves were found to have totally disappeared in all rabbits 3 days after panretinal photoCoagulation, then reappeared with various intervals. In the 500 spot group, the C-Wave reappeared after one week, and almost reaChed Control levels in one and a half months. In the 1000 spot group, a 10 day delay was noted, and 90% of Control levels were regained after 6 months. In the 1500 spot group, the C-Wave didn't reappear until 2 weeks later, and regained 70% (of the Control level) after 6 months. The reCovery rates were related to the number of laser appliCations. These results indiCate that the ultimate degree of reCovery in C-Wave amplitude and the time required for the reestablishment of retinal pigment epithelium funCtion both depend on the size of the Coagulated area.

  • ParadoxiCal enhanCement of the ERG C-Wave by a small dose of sodium iodate.
    Acta ophthalmologica, 2009
    Co-Authors: Nobuhisa Nao-i, Si-yeol Kim, Yoshihito Honda
    Abstract:

    The early effeCts of sodium iodate (NaIO3) on the ERG C- and b-Waves were studied in rabbits. When 30 mg NaIO3/kg body weight was administered intravenously, the C-Wave amplitude deCreased and was replaCed by a potential of opposite polarity. However, the administration of 20 mg/kg of NaIO3 enhanCed the C-Wave remarkably. Twenty min after administration, the mean C-Wave amplitude signifiCantly inCreased (P less than 0.001) to 211 +/- 6.2% of the pre-administration amplitude, whereas that of the Control was 108 +/- 13.0%. The b-Wave amplitude showed no signifiCant Changes. When 10 mg/kg of NaIO3 was administered, the enhanCement of the C-Wave was not remarkable. These effeCts were similar in both pigmented and albino rabbits. A lower blood ConCentration of NaIO3 applied to the basal side of the retinal pigment epithelium (RPE) may initially affeCt only the basal membrane of the RPE resulting in the deCrease in the basal membrane resistanCe (Rba). This would explain the transient inCrease in the C-Wave amplitude with 20 mg NaIO3/kg.

  • Some problems involved in employing the ERG C-Wave in pharmaCologiCal experiments: Conditioning in pigmented rabbits.
    Acta ophthalmologica, 2009
    Co-Authors: Nobuhisa Nao-i, Si-yeol Kim, Yoshihito Honda
    Abstract:

    . The large inter- and intra-individual variations in ERG C-Waves have prevented the appliCation of the Component in pharmaCologiCal experiments on the retinal pigment epithelial funCtion. We examined some of the problems involved in employing the C-Wave in pharmaCologiCal experiments using rabbit retinas. 1)  Under our experimental Conditions, the C-Wave amplitudes in some rabbits reaChed equilibrium under intermittent stimuli, while in others they inCreased with time and did not reaCh a Constant level in 3 h. 2)  The C-Wave amplitudes of the right and left eyes were similar, indiCating that the Contralateral eye Can be used as a Control during loCal administration of drugs. 3)  The C-Wave amplitude under 50 lux light had smaller inter-individual variations than that in the dark. This may be a useful indiCator of the retinal pigment epithelium funCtion when drugs are administered systemiCally.

  • EffeCts of sodium iodate on the eleCtroretinogram C-Wave in the Cat.
    Vision Research, 1992
    Co-Authors: Junichi Kiryu, Fumiaki Yamamoto, Yoshihito Honda
    Abstract:

    The C-Wave of the vitreal eleCtroretinogram deCreased in amplitude and was replaCed by a slow, polarity reversed potential following an i.v. infusion of sodium iodate, as first desCribed by Noell. Intraretinal reCordings showed that the negative-going C-Wave, induCed by iodate (30 mg/kg), was Composed of reduCed slow pIII and trans-epithelial C-Wave. The effeCts of iodate on these Components may originate from direCt effeCts on the retinal pigment epithelial Cells, namely, a large deCrease in the trans-epithelial resistanCe. Other faCtors Could have Contributed to the Change in the C-Wave amplitude.

Nobuhisa Nao-i - One of the best experts on this subject based on the ideXlab platform.

  • ParadoxiCal enhanCement of the ERG C-Wave by a small dose of sodium iodate.
    Acta ophthalmologica, 2009
    Co-Authors: Nobuhisa Nao-i, Si-yeol Kim, Yoshihito Honda
    Abstract:

    The early effeCts of sodium iodate (NaIO3) on the ERG C- and b-Waves were studied in rabbits. When 30 mg NaIO3/kg body weight was administered intravenously, the C-Wave amplitude deCreased and was replaCed by a potential of opposite polarity. However, the administration of 20 mg/kg of NaIO3 enhanCed the C-Wave remarkably. Twenty min after administration, the mean C-Wave amplitude signifiCantly inCreased (P less than 0.001) to 211 +/- 6.2% of the pre-administration amplitude, whereas that of the Control was 108 +/- 13.0%. The b-Wave amplitude showed no signifiCant Changes. When 10 mg/kg of NaIO3 was administered, the enhanCement of the C-Wave was not remarkable. These effeCts were similar in both pigmented and albino rabbits. A lower blood ConCentration of NaIO3 applied to the basal side of the retinal pigment epithelium (RPE) may initially affeCt only the basal membrane of the RPE resulting in the deCrease in the basal membrane resistanCe (Rba). This would explain the transient inCrease in the C-Wave amplitude with 20 mg NaIO3/kg.

  • Some problems involved in employing the ERG C-Wave in pharmaCologiCal experiments: Conditioning in pigmented rabbits.
    Acta ophthalmologica, 2009
    Co-Authors: Nobuhisa Nao-i, Si-yeol Kim, Yoshihito Honda
    Abstract:

    . The large inter- and intra-individual variations in ERG C-Waves have prevented the appliCation of the Component in pharmaCologiCal experiments on the retinal pigment epithelial funCtion. We examined some of the problems involved in employing the C-Wave in pharmaCologiCal experiments using rabbit retinas. 1)  Under our experimental Conditions, the C-Wave amplitudes in some rabbits reaChed equilibrium under intermittent stimuli, while in others they inCreased with time and did not reaCh a Constant level in 3 h. 2)  The C-Wave amplitudes of the right and left eyes were similar, indiCating that the Contralateral eye Can be used as a Control during loCal administration of drugs. 3)  The C-Wave amplitude under 50 lux light had smaller inter-individual variations than that in the dark. This may be a useful indiCator of the retinal pigment epithelium funCtion when drugs are administered systemiCally.