Local Electroretinogram Research Articles

Using Micro-Electrode-Array Recordings and Retinal Disease Models to Elucidate Visual Functions: Simultaneous Recording of Local Electroretinograms and Ganglion Cell Action Potentials Reveals the Origin of Retinal Oscillatory Potentials.

The electroretinogram (ERG) is an essential diagnostic tool for visual function, both in clinical and research settings. Here, we establish an advanced in vitro approach to assess cell-type-specific ERG signal components. Retinal explant cultures, maintained under entirely controlled conditions, were derived from wild-type mice and rd10 rod- and cpfl1 cone-degeneration mouse models. Local micro-ERG (µERG) and simultaneous ganglion cell (GC) recordings were obtained from the retinal explants using multi-electrode arrays. Band-pass filtering was employed to distinguish photoreceptor, bipolar cell, amacrine cell (AC), and GC responses. Scotopic and photopic stimulation discriminated between rod and cone responses in wild-type and mutant retina. The 25 kHz sampling rate allowed the visualization of oscillatory potentials (OPs) in extraordinary detail, revealing temporal correlations between OPs and GC responses. Pharmacological isolation of different retinal circuits found that OPs are generated by inner retinal AC electrical synapses. Importantly, this AC activity helped synchronise GC activity. Our µERG protocol simultaneously records the light-dependent activities of the first-, second-, and third-order neurons within the native neuronal circuitry, providing unprecedented insights into retinal physiology and pathophysiology. This method now also enables complete in vitro retinal function testing of therapeutic interventions, providing critical guidance for later in vivo investigations.

O-EV003. Role of multifocal electroretinogram in assessment of early retinal dysfunction in hypertensive patients

Introduction . Hypertensive retinopathy is the second most common cause of retinopathy following diabetes, probably caused by retinal ischemia as a consequence of atherosclerotic irreversible changes of systemic hypertension. Non-uniform functional retinal abnormalities are difficult to detect by full-field ERG and needs the disease to reach advanced changes to be affected. mfERG offers an objective noninvasive and reliable method to measure retinal function. It allows simultaneous recording of local ERG responses from different parts of the retina. Also previous studies suggested that the abnormalities in retinal electrophysiological studies usually precede fundus signs of retinopathy as mfERG is affected early by the neurodegenerative process. our aim in this study was to investigate localized retinal dysfunction in hypertensive patients using multifocal electroretinogram (mfERG) and to assess its sensitivity as an early predictor for the development of retinopathy in hypertensive patients. Methods . Ninety-eight eyes were included in this case-control study. Twenty-eight eyes of healthy subjects served as a control group (group I). Seventy eyes belonged to patients with systemic hypertension assigned into two groups; group II including 39 eyes of hypertensive patients with normal fundus and group III including 31 eyes of patients with signs of hypertensive retinopathy. All participants were subjected to complete ophthalmic and electrophysiological examination using mfERG. N1 and P1 wave amplitudes and implicit times from the central hexagon and four concentric rings across the visual field were analyzed. Results . mfERG amplitudes were significantly reduced in hypertensive group with retinopathy than in controls. N1 amplitude was significantly reduced in the most eccentric ring in eyes of hypertensive patients with normal fundus. Conclusion . mfERG is a sensitive objective tool for assessment of retinal dysfunction in hypertensive patients. mfERG amplitude is a promising predictor for early development of retinopathy in systemic hypertension.

Pattern‐stimulation in the complex management of patients with operated retinal detachment

AbstractIntroductionThe problem of increasing visual function after surgical treatment of retinal detachment retains its relevance. Existing methods do not take into account the possibilities of the retinal‐cortex system stimulation.ObjectiveEvaluation of the functional effect of pattern‐stimulation in the complex management of retinal detachment operated patients.Patients and methodsForty patients with an extrascleral retinal procedure. The median of age is 53.6 [23; 75] years. Patients in group 1a (10 eyes with macula‐on before surgery) and 1b group (with macula‐off before surgery) underwent a course of drug therapy (peptides, meldonium, antioxidants), patients of group 2a (10 eyes macula‐on before surgery) and 2b Groups (macula‐off before surgery) – a similar course of drug treatment combined with a pattern‐stimulation course. All groups are comparable in age, sex, visual acuity, data of electrophysiological studies – macular electroretinogram (ERG), visual evoked cortical potentials (VECP). According to the results of optical coherent tomography carried out before the start of treatment, there were no gross organic changes in the area of the macula in patients. Starting treatment 6 months after surgery. Evaluation of the treatment effectiveness after 3 months after its completion.ResultsIncreased visual acuity after treatment in group Ia occurred at 0.05, in group Ib by 0.03, in group IIa by 0.17, in group IIb by 0.21. The amplitude of wave‐a of macular ERG increased by 4.07 mV in group Ia, by 5.4 mV in group Ib, by 2.9 mV in group IIa, by 8.17 mV in group IIb; changes in wave amplitude‐in different directions: in group Ia, an increase of 3.5 mV, in group Ib a decrease of 0.4 mV, in group IIa and IIb an increase of 5.19 mV and 10.86 mV, respectively. VECP N 75 latency decreased by group Ia by 1.46 ms, by group 19.2 ms by group IIa, by 14.94 ms by group IIb, and increased by 1.1 ms by group Ib; P100 decrease in groups: Ia by 0.93 ms, IIa by 14.39 ms, IIb by 14.94 ms, increase in group Ib by 1.2 ms; the amplitude of the N75‐P100 VECP wave increased in all groups: Ia by 1.3 mV, Ib by 1.55 mV, IIa by 3.48 mV, IIb by 10.58 mV. An increase in visual acuity on the background of drug treatment correlated with an improvement in the amplitude characteristics of the local ERG (r = 0.47), using pattern stimulation with an increase in the amplitude characteristics of the VECP (r = 0.46).ConclusionUsing the stimulation pattern in complex management of the retinal detachment operated patients helps to improve the amplitude indices of local ERG and VECP by more than three times, reducing VECP latency values, increasing visual acuity 4 times in comparison with the routine drug therapy results in patients 1a and 1b groups. The results obtained indicate the feasibility of using the method of pattern‐stimulation in patients with operated retinal detachment to enhance the functional effect of surgical treatment.

Three-Dimensional Model of Electroretinogram Field Potentials in the Rat Eye.

The information derived from the electroretinogram (ERG), especially with regard to local areas of retinal dysfunction or therapeutic rescue, can be enhanced by an increased understanding of the relationship between local retinal current sources and local ERG potentials measured at the cornea. A critical step in this direction is the development of a robust bioelectric field model of the ERG. A finite-element model was created to simulate ERG potentials at the cornea resulting from physiologically relevant transretinal currents. A magnetic resonance image of a rat eye was segmented to define all major ocular structures, tissues were assigned conductivity values from the literature. The model was optimized to multi-electrode ERG (meERG) data recorded in healthy rat eyes, and validated with meERG data from eyes with experimental lesions in peripheral retina. Following optimization, the simulated distribution of corneal potentials was in good agreement with measured values; residual error was comparable to the average difference of individual eyes from the measured mean. The model predicted the corneal potential distribution for eight eyes with experimental lesions with similar accuracy, and a measure of pre- to post-lesion changes in corneal potential distribution was well correlated with the location of the lesion. An eye model with high anatomical accuracy was successfully validated against a robust dataset. This model can now be used for optimization of ERG electrode design, and to support functional mapping of the retina from meERG data via solving the inverse bioelectric source problem.

A novel high electrode count spike recording array using an 81,920 pixel transimpedance amplifier-based imaging chip

Microelectrode recording arrays of 60–100 electrodes are commonly used to record neuronal biopotentials, and these have aided our understanding of brain function, development and pathology. However, higher density microelectrode recording arrays of larger area are needed to study neuronal function over broader brain regions such as in cerebral cortex or hippocampal slices. Here, we present a novel design of a high electrode count picocurrent imaging array (PIA), based on an 81,920 pixel Indigo ISC9809 readout integrated circuit camera chip. While originally developed for interfacing to infrared photodetector arrays, we have adapted the chip for neuron recording by bonding it to microwire glass resulting in an array with an inter-electrode pixel spacing of 30μm. In a high density electrode array, the ability to selectively record neural regions at high speed and with good signal to noise ratio are both functionally important. A critical feature of our PIA is that each pixel contains a dedicated low noise transimpedance amplifier (∼0.32pA rms) which allows recording high signal to noise ratio biocurrents comparable to single electrode voltage amplifier recordings. Using selective sampling of 256 pixel subarray regions, we recorded the extracellular biocurrents of rabbit retinal ganglion cell spikes at sampling rates up to 7.2kHz. Full array local electroretinogram currents could also be recorded at frame rates up to 100Hz. A PIA with a full complement of 4 readout circuits would span 1cm and could acquire simultaneous data from selected regions of 1024 electrodes at sampling rates up to 9.3kHz.

ISCEV standard for clinical multifocal electroretinography (mfERG) (2011 edition)

The clinical multifocal electroretinogram (mfERG) is an electrophysiological test of local retinal function. With this technique, many local ERG responses are recorded quasi-simultaneously from the cone-driven retina under light-adapted conditions. This document, from the International Society for Clinical Electrophysiology of Vision (ISCEV: www.iscev.org ), replaces the ISCEV guidelines for the mfERG published in 2007. Standards for performance of the basic clinical mfERG test with a stimulus array of 61 or 103 hexagons, as well as for reporting the results, are specified.

Transcranial magnetotherapy for the correction of initial manifestations of diabetic retinopathy in children

This study included 45 children at the age from 5 to 17 years with type I diabetes mellitus complicated by diabetic retinopathy. All the patients showed retinal thickening at the macula and reduced amplitude of local electroretinogram suggesting compromised capillary circulation. The capillary blood flow was corrected by transcranial magnetotherapy with the use of an AMO-ATOS Ogolovie unit. The results of the treatment were evaluated from characteristics of laser Doppler flometry. A course of transcranial magnetotherapy comprising 10 daily seances resulted in a significant increase of microcirculation index, respiratory rhythm, and myogenic tone (by 1.64, 1.35, and 1.16 times respectively). In addition, morphometric and electrophysiological properties of the retina underwent positive changes. Transcranial exposure to the traveling magnetic field is recommended for the correction of intraocular microcirculation and prevention of diabetic macular oedema.

ISCEV guidelines for clinical multifocal electroretinography (2007 edition)

The clinical multifocal electroretinogram (mfERG) is an electrophysiological test of local retinal function. With this technique, many local ERG responses, typically 61 or 103, are recorded from the cone-driven retina under light-adapted conditions. This document specifies guidelines for performance of the test. It also provides detailed guidance on technical and practical issues, as well as on reporting test results. The main objective of the guidelines is to promote consistent quality of mfERG testing and reporting within and among centers. These 2007 guidelines, from the International Society for Clinical Electrophysiology of Vision (ISCEV: http://www.iscev.org), replace the ISCEV guidelines for the mfERG published in 2003.

Local and multifocal ERG in age‐related macular degeneratıon.

Abstract Purpose: To assess the macular ERG responses in different forms of AMD with OCT‐visualisation. Methods: 60 patients (120 eyes) wıth AMD, aged 57‐82, were examined. The groups were formed based on clinical examination, OCT and fluorescein angiography data. Local ERG (L‐ERG) to a red and green stımulus was recorded wıth MBN ERG system (Russıa). Multıfocal ERG was recorded wıth RETIscan system (Roland Consult, Germany). Results: In group 1 wıth hard drusen (18 eyes) ERG responses were in normal range. In group 2 with soft confluent drusen (18 eyes) a‐wave implicit tıme (IT) was prolonged (p=0,007);N1 of mfERG in normal range. b‐wave amplitude of L‐ERG to red stimulus was reduced (p=0,014), P1 of mf‐ERG reduced in fovea and parafovea (р<0,001). In a group 3а (31 eyes) wıth focal RPE atrophy,a‐wave IT of M‐ERG prolonged (p=0,002), P1 reduced in fovea (p=0,04). In a group 3b (16 eyes) with focal RPE atrophy and hyperpigmentation (VA 0,4‐0,1) a‐ and b‐wave reduced (p<0,001),P1 reduced in fovea and parafovea (р<0,05), N1 in foveal hexagone (p=0,04). In a group 4a with CNV with CMO foveal and parafoveal b‐wave amplitude reduced (p<0,05), P1 and N1 reduced (р<0,001). P1 in paramacular ring was reduced (р<0,05). In group 4b with RPE‐detachment a‐wave prolonged, a‐and b‐wave reduced, P1 and N1 reduced (р<0,001). Conclusions: The most sensitive indicators of macular dysfunction in AMD are the implicit time of a‐wave to a red stimulus local ERG and P1 response density of mf ERG in foveal hexagone. Normal amplitude and implicit time of N1 in soft drusen and early RPE‐atrophy in eyes with prolonged a‐wave of local ERG provides the evidence of smaller contibution of cones to N1 of FOK of mf ERG.

Spatiotemporal receptive field properties of epiretinally recorded spikes and local electroretinograms in cats

BackgroundReceptive fields of retinal neural signals of different origin can be determined from extracellular microelectrode recordings at the inner retinal surface. However, locations and types of neural processes generating the different signal components are difficult to separate and identify. We here report epiretinal receptive fields (RFs) from simultaneously recorded spikes and local electroretinograms (LERGs) using a semi-chronic multi-electrode in vivo recording technique in cats. Broadband recordings were filtered to yield LERG and multi unit as well as single unit spike signals. RFs were calculated from responses to multifocal pseudo-random spatiotemporal visual stimuli registered at the retinal surface by a 7-electrode array.ResultsLERGs exhibit spatially unimodal RFs always centered at the location of the electrode tip. Spike-RFs are either congruent with LERG-RFs (N = 26/61) or shifted distally (N = 35/61) but never proximally with respect to the optic disk. LERG-RFs appear at shorter latencies (11.9 ms ± 0.5 ms, N = 18) than those of spikes (18.6 ms ± 0.4 ms, N = 53). Furthermore, OFF-center spike-RFs precede and have shorter response rise times than ON-center spike-RFs. Our results indicate that displaced spike-RFs result from action potentials of ganglion cell axons passing the recording electrode en route to the optic disk while LERG-RFs are related to superimposed postsynaptic potentials of cells near the electrode tip.ConclusionBesides contributing to the understanding of retinal function we demonstrate the caveats that come with recordings from the retinal surface, i.e., the likelihood of recordings from mixed sets of retinal neurons. Implications for the design of an epiretinal visual implant are discussed.

Assessing Responses of the Macula in Patients with Macular Holes using a New System Measuring Localized Visual Acuity and the mfERG

To evaluate acuity and multifocal electroretinogram (mfERG) responses from the macula in affected and unaffected fellow eyes of patients with macular holes. We tested 10 eyes with macular hole and 10 fellow eyes from 11 patients. We measured local visual acuity thresholds at 27 discrete locations within 21 degrees diameter using the Functional Fundus Imaging System (FFIS), a psychophysical system that measures visual acuity as a function of visual field location, and local ERG responses within 45 degrees diameter using the mfERG. In the affected eyes, the mean FFIS visual acuity thresholds were significantly elevated within the central 21 degrees diameter area, compared to a group of control eyes. No significant differences were found between the acuities of the fellow eyes compared to those of the control group. The amplitudes of the first positive peak of the mfERG were reduced in the central 7.8 degrees in affected eyes. In the central 2 degrees , 4 out of 10 affected eyes showed non-measurable ERG signals. The remaining six eyes showed significantly reduced mean amplitudes, but not delayed implicit times, when compared to the control group. For the fellow eyes, the mean amplitudes of the mfERG and implicit times did not differ from the means of the control eyes. Both local psychophysical and electrophysiological testing demonstrated retinal dysfunction extending beyond the site of the macular holes in some patients (three of the patients had central mfERG amplitudes falling within the normal range).

The multifocal electroretinogram.

The multifocal electroretinogram (mfERG) technique allows local ERG responses to be recorded simultaneously from many regions of the retina. As in the case of the full-field ERG, the ganglion cells contribute relatively little to the response, which originates largely from the outer retina. The mfERG is particularly valuable in cases in which the fundus appears normal, and it is difficult to distinguish between diseases of the outer retina and diseases of the ganglion cells and/or optic nerve. The mfERG can also help to differentiate among outer retinal diseases, to follow the progression of retinal diseases, and, with the addition of the mfVEP, to differentiate between organic and nonorganic causes of visual loss. However, because the difficulties encountered in recording and analyzing mfERG responses are greater than those involved in full-field ERG testing, mfERG testing is best left to centers with an electrophysiologist familiar with the mfERG test. Although this technique is relatively new and standards are still being developed, centers capable of recording reliable mfERG responses can be found in hundreds of locations around the world.

Effect of 2-amino-4-phosphonobutyrate on the OFF responses of frog retinal ganglion cells and local ERG after glycinergic blockade.

Perfusion with the ON channel blocker 2-amino-4-phosphonobutyrate (APB) of dark adapted frog eyecups not only abolished the ganglion cells' (GC) ON responses and the ERG b-wave, but markedly potentiated the OFF responses of ON-OFF and phasic OFF-GCs and the d-wave amplitude of simultaneously recorded local ERG. Glycinergic blockade by strychnine prevented this potentiating effect in 31 out of 69 GCs, but did not change it at all in the other cells. At the same time the d-wave potentiation was preserved during the glycinergic blockade in all eyecups. The results indicate that glycinergic transmission is involved in the inhibition exerted from ON upon OFF channel in some but not all frog retinal GCs.

Effects of atropine on refractive development, dopamine release, and slow retinal potentials in the chick.

Atropine has previously been found to suppress visually induced myopia both in animals and humans. The mechanism of its action is unclear. We have studied its retinal effects in an in vitro preparation, using the retina-pigment epithelium-choroid complex of the chick eye. In vivo, deprivation myopia was induced by translucent goggles. Atropine solution was injected into the vitreous at two-day intervals. Dopamine release from the retina following atropine injection in vivo and from the in vitro retina preparation was quantified by HPLC-EC. In vitro preparations of the isolated chick retina-pigment epithelium-choroid were superfused with atropine. Light-induced potentials (local ERG), slow standing potentials from the retinal pigment epithelium/neural retina, and extracellular potassium concentrations were recorded. In line with previous findings, intravitreal injections of atropine (25 microg, 250 microg) reduced deprivation myopia in a dose-dependent manner. Atropine increased the release of the neurotransmitter dopamine into the superfusate in vitro at 100-500 microM and into the vitreous in vivo at 250 microg. Before an increase was measured in the vitreous, the retinal dopamine content was elevated. In concentrations equivalent to the intravitreal concentration to suppress myopia in vivo (200-800 microM), atropine induced spreading depression (SD) in the in vitro preparation. In contrast, muscarinic agonists, acetylcholine and pilocarpine, did not induce SD. Atropine reduced the ERG b- and d-wave, led to damped oscillations of RPE potentials, and reversed the ERG c-wave. Atropine suppressed myopia only at doses at which severe nonspecific side effects were observed in the retina. Atropine seems to intrude massively into the vital functions of the retina as indicated by the occurrence of SD. We conclude that atropine, by inducing SD, boosts neurotransmitter release from cellular stores, which may cancel out a presumed retinal signal that controls eye growth and through this, myopia.

Clinical applications of multifocal electroretinography.

The multifocal ERG using the m-sequence stimulation technique allows the derivation of 61 - 241 local ERG signals in a central visual field of about 60 degree diameter in a short time between 4 and 16 min. A recording in a light adapted state offers local information comparable to cone responses in the full-field ERG. Retinal functional losses due to regional disorders in outer retinal layers can be described in detail with this technique. In maculopathies decreased or absent central ERGs are found surrounded by normal ERG. The extent of the central lesion can be estimated. In diseases of the outer retina the pattern of distribution of multifocal ERG activity is similar to the the pattern of the visual field defect. In addition to decreased ERG amplitudes a delay of implicit time may be an important sign of pathology, i.e. the pronounced delay of implicit times in the periphery in retinitis pigmentosa and the implicit time delays in regions associated with retinal edema like CRVO and cystoid macula edema in intermediate uveitis. No simple correlation of the first order kernel multifocal ERG and field defects could be found in disorders of the ganglion cell layer. The multifocal ERG is therefore useful in the differential diagnosis of retinal and optic nerve diseases.

Effects of Stimulus Blocking, Light Scattering, and Distortion on Multifocal Electroretinogram

Purpose: To investigate how the multifocal electroretinogram (ERG) is altered in conditions of blocking, light scattering, or distortion of the stimulus that are seen in ocular pathologies. Methods: A central 40°-diameter stimulus pattern consisting of 61 hexagons was presented on a cathode ray tube monitor at a rate of 75 Hz according to the pseudo-random binary M sequence by the Veris computer program. Localized responses corresponding to each hexagon and ERG topographies were displayed on the computer screen. Central scotoma was simulated by blocking the central area of the stimulus, visual field constriction by blocking the outer area of the stimulus, mild cataract by using acrylic filters that caused light scatter, and epiretinal membrane by using a wavy plastic plate that produced metamorphopsia. Results: The responses from the blocked area were nonrecordable whether blockage was central or peripheral; responses from the adjacent unblocked area had a larger amplitude when large areas of the stimulus were blocked. The light scatter that decreased vision from 20/20 to 20/70 did not significantly decrease response amplitudes. Responses from areas in which the stimulus pattern was distorted were minimally affected. Conclusions: The results show that the system records local ERGs from the macula and outside the macula. It can detect the area where the stimulus is blocked. Moderate light scattering and distortion do not cause loss of local ERG characteristics.

Electroretinogram of the parietal eye of lizards: photoreceptor, glial, and lens cell contributions.

Local electroretinograms (ERGs) were recorded in the parietal eye of Xantusia vigilis. The responses to monochromatic light under dark- and light-adapted conditions were studied. We found that two antagonistic chromatic mechanisms dominate the overall response. With the electrode tip in the lumen of the eye, light stimulation under dark-adapted conditions evoked responses of negative polarity with maximum sensitivity to green light. Intense green background illumination saturated the green-sensitive mechanism, and superposition of a blue stimulus then elicited responses of opposite polarity, driving the potentials back toward the dark resting level. The spectral sensitivities of the two chromatic mechanisms were determined using chromatic adaptation. The lower threshold, green-sensitive mechanism has a maximum sensitivity at 495 nm while the antagonistic mechanism, with its maximal spectral sensitivity at 430 nm, is at least 2 log units less sensitive. The polarity of the ERG recording inverts as the electrode traverses the photoreceptor layer, suggesting that the photoreceptors are the major source of the ERG. This result was confirmed with intracellular recordings from photoreceptors, glial, and lens cells. The glial and lens cells of the parietal eye respond to local changes in [K+]o. Intracellular recordings of the responses of these cells to light stimuli follow time courses similar to changes in extracellular potassium concentrations measured with K+ -specific electrodes. These results suggest that the glial and lens cell membranes are highly permeable to potassium and, therefore, the electrical responses of these cells are evoked by changes in [K+]o elicited by light stimulation of the photoreceptors. Nevertheless, the major component of the parietal eye ERG is the photoreceptor signal. A circuit model of the ERG sources is presented.

Effect of Glycinergic Blockade on Light Responses of Frog Retinal Ganglion Cells

The effect of glycinergic blockade by strychnine on light responses of ganglion cells (GC) was investigated in perfused dark adapted eyecups of frog ( Rana ridibunda). We found that 78% of successfully registered GCs were strychnine-sensitive, but the blocker's effect differed among various cells. In the half of the strychnine-sensitive ON-OFF GCs strychnine markedly potentiated in nearly equal degree their ON and OFF responses, but in a few cases potentiation of only the OFF responses was observed. In three cells, instead of potentiation, diminution of both the ON and OFF responses of ON-OFF GCs was obtained. In some cases the glycinergic blockade changed the apparent cell's type and among these cells it was interesting to observe an opposite effect of the glycinergic blockade on the ON and OFF responses. In contrast to the diverse effects on the ganglion cells' activity, strychnine had one and the same potentiating effect on the amplitude of both b- and d-wave of the local ERG. Our results indicate that the glycinergic interneurons are involved in different networks in the inner plexiform layer of frog retina.

The spatial distribution of ERG losses across the posterior pole of glaucomatous eyes in multifocal recordings.

Australian and New Zealand Journal of OphthalmologyVolume 24, Issue S2 p. 28-31 Free Access The spatial distribution of ERG losses across the posterior pole of glaucomatous eyes in multifocal recordings , Corresponding Author *The Eye and Vision Research Institute, Electrophysiology Department.Visiontest Australia, Suite 5, Level 5, 187 Macquarie Street, Sydney 2000, New South Wales.Search for more papers by this authorL. Buckland BSc, Corresponding Author L. Buckland BSc †Eye Clinic, Prince of Wales Hospital.Visiontest Australia, Suite 5, Level 5, 187 Macquarie Street, Sydney 2000, New South Wales.Search for more papers by this author , Corresponding Author *The Eye and Vision Research Institute, Electrophysiology Department.Visiontest Australia, Suite 5, Level 5, 187 Macquarie Street, Sydney 2000, New South Wales.Search for more papers by this authorL. Buckland BSc, Corresponding Author L. Buckland BSc †Eye Clinic, Prince of Wales Hospital.Visiontest Australia, Suite 5, Level 5, 187 Macquarie Street, Sydney 2000, New South Wales.Search for more papers by this author First published: May 1996 https://doi.org/10.1111/j.1442-9071.1996.tb00987.xCitations: 7AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References 1 Vaegan, Graham SL, Goldberg I., Millar TJ. Selective reduction of oscillatory potentials and patterr electroretinograms after retinal ganglion cell damage 05 disease in humans or by kainic acid toxicity in cat. Doc Ophthalmologica 1991; 77: 237– 53. 2 Vaegan, Graham SL, Goldberg I., Buckland L., Hollows FC Flash and pattern electroretinogram changes with optk atrophy and glaucoma. Exp Eye Res 1995; 60: 697– 706. 3 Yin ZQ, Vaegan, Millar TJ, Sarks J., Sarks SH. Choroida atrophy in chronic primary open angle glaucoma. [Abstrac 2714] Invest Ophthalmol Vis Sci 1994; 35(Suppl.): 1842. 4 Yin ZQ, Vaegan, Millar TJ, Sarks J., Sarks SH. The locui of choroidal blood vessel loss in chronic primary oper angle glaucoma. [Abstract 4446] Invest Ophthalmol Vi: Sci 1995; 36(Suppl.): S964. 5 Vaegan, Yin ZQ, Beaumont P. Delayed choroidal filling across the posterior pole of glaucomatous eyes shown by fluorescein angiography. [Abstract 4452] Inves Ophthalmol Vis Sci 1995; 36(Suppl.): S965. 6 Nork TM, Poulsen GL, Vaegan, Sarks SH. Photoreceptoi damage and loss in human eyes with primary open angl> glaucoma. [Abstract 1546] Invest Ophthalmol Vis Sc 1995; 36(Suppl.): S331. 7 Yin ZQ, Vaegan, Millar TJ, Beaumont P., Sarks J., Sarks SH. The locus of choroidal blood vessel loss in chronic primary open angle glaucoma. [Abstract 4446] Invest Ophthalmol Vis Sci 1995; 36(Suppl.): S964. 8 Sutter EE, Tran D. The field topography of ERG components in man | I. The photopic luminance response. Vision Res 1992; 32: 433– 46. 9 Sutter EE, Vaegan. Lateral interaction component and local luminance nonlinearities in the human pattern reversal ERG. Vision Res 1990; 30: 659– 71. 10 Vaegan, Sutter EE. Fundamental differences between the nonlinearities of pattern and focal electroretinograms. Doc Ophthalmologica 1990; 76: 13– 25. 11 Sutter EE, Bearse MA. Extraction of a ganglion cell component from the corneal response. Vision Science and its Applications. 1995 OSATechnical Digest Series, Vol 1. Optical Society of America, Washington DC. 1995; 310– 13. 12 Vaegan, Buckland L. Outer retinal changes in early glaucoma detected with the Sutter local luminance ERG field test. Proceedings of the 33rd ISCEV Symposium, Athens, Greece. 16–20 June 1995. 13 Hennessy MP, Vaegan. Amplitude scaling relationships of Burian-Allen, gold foil, and Dawson Trick and Iitzkow electrodes. Doc Ophthalmologica 1995; 89: 235– 48. 14 Vaegan, Buckland L. Relationship between means and variances of ERGs obtained with gold foil and DTL electrodes across the full range of recordable amplitudes. Proceedings of the 33rd ISCEV Symposium, Athens, Greece. 16–20 June 1995. 15 Holder GL. Pattern electroretinography in the evaluation of glaucoma and in optic nerve function. In JR Heckenlively, GB. Arden Principles and Practice Of Clinical Electrophysiology Of Vision. St Louis : Mosby Year Book, 1991; 549– 56. 16 James AC, Maddess T., Wine S., Goldberg I. A novel multiple region PERG for glaucoma. [Abstract 4317] Invest Ophthalmol Vis Sci 1994; 35(Suppl.): 2187. Citing Literature Volume24, IssueS2May 1996Pages 28-31 ReferencesRelatedInformation

Retinal Oxygen Tension and the Electroretinogram During Arterial Occlusion in the Cat

Purpose. Retinal oxygen tension (PO 2 ), photoreceptor oxygen consumption (QO 2 ), the local electroretinogram (LERG), and the vitreally recorded electroretinogram (ERG) were evaluated during retinal artery occlusion in the cat. The feasibility of supplying the retina with oxygen during occlusion by ventilation with 100% O 2 was evaluated. Methods. Double-barreled oxygen microelectrodes were used to measure intraretinal PO 2 and LERGs in anesthetized cats before, during, and after occlusion of a single retinal artery. Outer retinal (photoreceptor) QO 2 was determined from retinal PO 2 profiles. Results. During air breathing, occlusion obliterated the LERG b-wave and reduced the vitreal ERG by the amount expected from the area supplied by the occluded vessel. The PO 2 in the entire inner retina was zero, and photoreceptor QO 2 was decreased by approximately 25%. Inspiration of 100% O 2 restored the b-wave amplitude to approximately 50% of normal and increased the amount of O 2 reaching the inner retina. Hyperoxia could not guarantee nonzero PO 2 across the entire retina in either darkness or light, but it elevated the average PO 2 in the innermost 25% of the retina to more than 20 mm Hg. The b-wave amplitude must have been affected by some factor in addition to local hypoxia, because the amplitude was not correlated with inner retinal PO 2 during occlusion, and a normal PO 2 did not result in a normal LERG. Effects of 2 to 2.5 hours of occlusion were reversible if 100% O 2 inspiration was maintained during most of the occlusion. Conclusions. Ventilation with 100% O 2 during occlusion increased the PO 2 across most of the retina and partially restored the LERG b-wave, but the tissue near the vitreous was still sometimes anoxic. The illumination status seemed to make little difference. Inspiration of elevated O 2 might be beneficial in treating retinal vascular occlusive disease, although it alone cannot completely maintain retinal function