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PubMed2001

Multifocal electroretinography in multifocal choroiditis and the multiple evanescent white dot syndrome.

PURPOSE: To study and compare the findings on multifocal electroretinography (MERG) between multifocal choroiditis (MFC) and the multiple evanescent white dot syndrome (MEWDS). SUBJECT AND METHODS: Patients were recruited prospectively from the Department of Ophthalmology & Visual Sciences at the University of Iowa Hospitals & Clinics. They were evaluated using Goldmann visual fields (GVF) and MERG. Patients were diagnosed as having either MFC or MEWDS based on their clinical findings before MERG testing. RESULTS: Nineteen patients (23 eyes) were included in the study. Eleven patients were diagnosed with MFC and eight patients with MEWDS. Fourteen eyes with MFC and seven eyes with MEWDS were tested with MERG during the acute phase of their respective conditions. Fourteen patients (8 MFC and 6 MEWDS) were followed serially with MERG. Patients with MEWDS demonstrated focal depression corresponding to GVF defects with subsequent near total recovery of the MERG to baseline. Patients with MFC typically demonstrated diffuse loss of function over the entire test field. Focal scotomata, in addition to the diffuse depression, could be identified in 7 of 14 patients. Patients with MFC demonstrated only partial or no recovery of MERG following acute episodes, which was significantly different from the course followed by patients with MEWDS (P < 0.001, Fisher's exact test). CONCLUSION: Multifocal electroretinography differentiates MFC from MEWDS. Patients with MFC have permanent damage to the retina with diffuse depression of MERG. Patients with MEWDS, however, typically demonstrate greater focal loss initially on MERG followed by nearly full recovery of first order retinal function.

Acute Disease↗

PubMed1998

Multifocal electroretinography in patients with Stargardt's macular dystrophy.

AIMS: To describe the topography of multifocal electroretinograms (ERGs) and to explore its diagnostic value in patients with Stargardt's macular dystrophy (SMD). METHODS: 51 patients with SMD were examined by means of the m-sequence technique to characterise the topography of electroretinographic responses in the central visual field. The results were compared with data from 30 normal volunteers. RESULTS: In 49 of 51 patients with SMD, macular electroretinographic activity was markedly diminished or non-detectable. Towards more peripheral areas, ERG responses of the SMD patients approached those of normals. Implicit times were not markedly delayed at any eccentricity. CONCLUSION: In contrast with Ganzfeld electroretinography, multifocal electroretinography is useful to detect foveal dysfunction in SMD. Areas of dysfunction were found to be usually larger than expected from psychophysical measurements and morphological alteration. In early stages of the disease it was possible to detect foveal dysfunction, even in patients lacking morphological fundus changes and with good visual acuity.

Adolescent↗

PubMed1977

Psychophysical applications of human electroretinography.

Rapid developments in human electroretinography during recent decades have greatly increased its value for investigating psychophysical problems. This review of the current status of electroretinography considers the response waveform, recording techniques, and data analysis. Several examples of electroretinal data that have psychophysical significance are presented.

Electroretinography↗

PubMed1976

Clinical electroretinography by the skin electrode and signal averaged method.

Conventional electroretinography requires the application of a ring or contact electrode to the anaesthetized cornea. A simplified method for routine clinical electroretinography is described. Skin electrodes are used, signals are appropriately filtered, amplified, passed to a signal averager and displayed on an oscilloscope. Sixteen sweeps are employed and a wave form similar in appearance and frequency content to that obtained by the corneal electrode method, is obtained. Values for the light and dark adapted eye in normal subjects (pupils undilated), are provided and the findings in the stages of retinitis pigmentosa and in other disease states, are noted.

Adolescent↗

PubMed1991

[Clinical electroretinography in the dog. Part 1].

In the first of three parts of this investigation the clinical importance and the principal indications for electroretinography are presented. The histology and ultrastructure of the retina with special emphasis on the photoreceptors and the second order neurons are discussed. A section is devoted to the history of electroretinography in man and animals. The components of the ERG and their origin are discussed.

Animals↗

PubMed1993

Multimodality evoked potentials and electroretinography in a test battery for an early diagnosis of brain death.

A test battery conformed by multimodality evoked potentials (MEP) and electroretinography (ERG) was applied to 30 brain-dead patients. Three patterns of brainstem auditory evoked potentials (BAEPs) were observed: (1) No identifiable waves (73.34%); (2) an isolated bilateral wave I (16.66%) and (3) an isolated unilateral wave I (10%) (Fig. 1,2,3). Waves II, III, IV, and V were not observed in any of the cases. Whenever wave I was recorded, it was always significantly delayed. For short latency evoked potentials (SSEPs) a characteristic pattern was found: absence of cortical N20 and later responses in scalp-cephalic records and preservation of the so-called subcortical components in the rest of the derivations. For visual evoked potentials (VEPs) and electroretinography (ERG) the same pattern was found in all cases: when a cephalic reference was used for both, VEPs and the ERG, waves a and b of the ERG were recognized in all cases. The visual evoked responses consisted of waves with less amplitude but very similar in latency and morphology to the ERG. When a non-cephalic channel was chosen for the ERG and VEPs, the ERG waves showed no changes either in morphology or in latency, while the VEP lead showed no response. It is discussed that the consideration of MEP and ERG in a battery test to evaluate brain-dead patients increase diagnostic reliability, which is fundamental for an early diagnosis of brain death.

Adolescent↗

PubMed1975

Visual fields and electroretinography following extensive photocoagulation.

Twenty-four patients with proliferative or preproliferative diabetic retinopathy underwent extensive argon laser photocoagulation in one eye. Detailed central and peripheral visual-field examinations and electroretinography were performed before treatment, and at intervals after treatment. Visual field changes were as follows: (1) eight patients had only mild to moderate constriction of all isopters, (2) 11 had discrete scotomata in addition, (3) two had prominent nerve-fiber-bundle defects, (4) three had severe constriction of all isopters, save (in two) that to the largest peripheral test object. Electroretinographic b-wave amplitudes were reduced an average of 40% to white test flashes. Blue test flashes showed an even larger reduction of the rod response. This suggests the receptors in approximately 40% of the retinal area are destroyed by such extensive photocoagulation, covering predominantly that part of the retina that has the highest concentration of rods.

Adult↗

PubMed1976

A Ganzfeld stimulator for electroretinography.

The design of a ganzfeld stimulator for electroretinography affects both clinical results and ease of operation. Several advantageous design differences from a recently described ganzfeld stimulator are (1) close proximity of the flash electrode to the surface of the sphere to increase the intensity and uniformity of the stimulus; (2) provision for interposing color filters in the background light; (3) use of a diffusing filter in the background light; and (4) placement of the stimulus flash anteriorly to avoid uneven illumination of the retina. Details of construction are proveded for two models and the specific advantages of each design are noted.

Electroretinography↗

PubMed1977

Noninvasive copper measurement in chalcosis: comparison with electroretinography and ophthalmoscopy.

The developement of chalcosis bulbi in rabbits' eyes is investigated by ophthalmoscopy, electroretinography, and diagnostic x-ray spectrometry (DXS), a new method for in vivo analysis and quantitation of metals. The DXS is shown to provide an effective method for the early detection of intraocular foreign bodies (IOFB) dissolution. The ophthalmoscopic changes observed in chalcosis are discussed in relation to dissolution of IOFB and electroretinographic findings.

Animals↗

PubMed1982

Electroretinography and retinitis pigmentosa. No discrimination between genetic subtypes.

Electroretinography (ERG) has been utilized to claim that the various hereditary subtypes of retinitis pigmentosa (RP) could be distinguished according to the temporal characteristics of the b wave. This study compares two different ERG techniques, one utilizing constant amplitude response and the other balanced photopic and scotopic stimuli, for the early diagnosis of RP. Both methods were found to be reliable objective tests for diagnosing RP. Neither test could differentiate between dominant, autosomal recessive, or X-linked RP.

Adolescent↗

PubMed1995

An updated standard for clinical electroretinography.

The value of the electroretinogram (ERG) in clinical practice depends in part on its consistency and the ability to compare results with other laboratories and the literature. These issues were addressed by the publication of the International Standard for Clinical Electroretinography in 1989. This Standard provided technical information and defined a core of basic test procedures and test responses (Figure) to ensure that ERGs performed worldwide would be equivalent for clinical and research purposes. Most major laboratories now subscribe to the tenets of the Standard, and it should be noted that the Standard does not limit laboratories from doing additional specialized tests (beyond the recommendations) for either clinical purposes or research. Since science and medicine are not static, the original Standard mandated revision every 4 years by the International Society for Clinical Electrophysiology of Vision. The first revision, titled "Standard for Clinical Electrophysiology (1994 Update)," has just been published, and it contains changes and new provisions that should be reviewed carefully by those who perform ERGs. The major changes and additions in the updated ERG Standard are as follows.

Adult↗

PubMed1988

Hereditary retinal degeneration in the Abyssinian cat: developmental studies using clinical electroretinography.

Electroretinography was performed in 10 Abyssinian cats, homozygous for a hereditary retinal degenerative disease but still with an ophthalmoscopically normal retina, and in 11 mixed-breed controls, all between the ages of 8 and 104 weeks. A significant reduction of maximum dark-adapted b-wave amplitude was found in affected kittens as young as 8-16 weeks when compared with controls, although there was no major difference in dark-adapted b-wave threshold or implicit time for the b-wave between affected and controls. For cats 33-104 weeks, similar results were obtained except for the b-wave threshold, which was elevated 2.5 log units in one of the affected cats. No significant difference in 30-Hz cone flicker responses were found between affected and controls at any age studied. In the time period 17-32 weeks affected Abyssinian kittens could not be differentiated from controls by means of the electroretinogram. The significant reduction in scotopic b-wave maximum amplitudes in young affected kittens (8-16 weeks) in conjunction with normal thresholds suggests an early drop-out of rods. It is clear that affected kittens can be differentiated electrophysiologically from controls long before there are ophthalmoscopic signs of retinal disease.

Aging↗

PubMed1989

An international standard for electroretinography.

An international standard procedure for electroretinography (ERG) has finally been established. It represents a minimum protocol to record five basic signals (rod response, scotopic maximal response, oscillatory potentials, single-flash cone response, 30-Hz flicker response). Individual laboratories may continue to do additional or specialized procedures, but the hope is that all laboratories will include "standard" responses in their routine protocols so ERG data can be compared throughout the world for patient care and for research.

Electroretinography↗

PubMed1992

New noncorneal HK-loop electrode for clinical electroretinography.

A new noncorneal electrode for clinical electroretinography was developed. It consists of a thin wire forming a loop modeled to fit into the lower conjunctival sac. Electrical contact is made with the scleral conjunctiva through an exposed portion of otherwise insulated wire. The recorded pattern electroretinograms are in the same amplitude range as if recorded by the gold foil electrode, while the flash electroretinograms with the new electrode are of about two-thirds the amplitude of corneal electrodes. The new electrode is more durable and hence less expensive than gold foil electrodes and can likewise be used without topical anesthetic. Cleaning is easy and effective. The electrode rarely causes discomfort and produces stable responses for at least 2 hours. The electrode aims to match stability of skin electrodes with sensitivity of fragile foil and fiber electrodes.

Conjunctiva↗

PubMed1991

Pattern electroretinography in senile macular degeneration.

The value of pattern electroretinography (PERG) for the detection and differentiation of senile macular degeneration (SMD) was assessed. A group of patients with atrophic SMD and a group with exudative SMD were compared with an age-matched reference group. Differences were only found in visual acuity and in the amplitude of the negative peak N95. No statistical differences between the atrophic and exudative groups were found. Conclusions may be drawn from these results with regard to the use of PERG in senile macular degeneration.

Aging↗

PubMed1991

Correlations between electroretinography, morphology and function in retinitis pigmentosa.

In a retrospective study, data from 116 patients suffering from different forms of retinitis pigmentosa were analysed, and 15 categories comprising altogether 34 symptoms or clinical signs were tabulated from each patient's record. The 15 categories evaluated were: visual acuity, visual field diameter, ring or central scotoma, nyctalopia, susceptibility to glare, refraction, cataract, electroretinography, colour of the optic disc, bone-spicule pigmentation of the retina, retinal vessel diameters, tapetoretinal reflex, sex, heredity, and age. Correlations between the tabulated 34 subcategories or symptoms were calculated. The results of a factorial analysis of the data showed a high number of highly significant correlations between the different categories. It seemed possible to discriminate between two groups of categories, with the members of each group being closely correlated but correlations with members of the other group being much smaller, if not nonexistent. We tentatively associated the first group with the functional state of the central retina and the second group with the state of the peripheral retina.

Adolescent↗

PubMed1987

Atraumatic loop electrodes for electroretinography.

A simple method is described for producing inexpensive, atraumatic electrodes for electroretinography. Scleral contact is obtained by a loop of ultra-lightweight stainless steel wire placed between the eye and lower lid. Recordings obtained by this method in animals are equal to those recorded with needle electrodes from the same ophthalmologically normal dog are presented.

Animals↗

PubMed1979

[Information conveyed by electroretinography (author's transl)].

Clinical evaluation of the function of the human retina by subjective, psychophysical tests can be complemented by objective, electrophysiological methods such as electroretinography. The electroretinogram (ERG) is a transient action potential generated by the vertebrate retina in response to light. Using standardized stimulation, after assessing the normal range of the ERG the investigator can establish early diagnosis, improve prognostic statements and document the course of retinal diseases. A method to selectively stimulate the rod- and cone-system, developed by Gouras and co-workers, has proved to allow further differentiation of heredodegenerative diseases of the retina. The ERG monitors objectively the function of the retina in infants uncapable of cooperating in psychophysical tests and in patients suffering from opacities of the optic media. ERG results should be evaluated synoptically with psychophysical data, ophthalmoscopy, fluoresceinangiography and possibly with EOG and VER recordings. Under experimental conditions the ERG serves to monitor the sensitivity of the retina in vivo as well as in vitro in physiological, pharmacological and toxicological studies.

Diagnosis, Differential↗