The electroretinogram (ERG) is a diagnostic test that measures the . The multifocal ERG (mfERG) simultaneously measures local retinal. Multifocal electroretinography (mfERG) is an objective, noninvasive examination for the assessment of visual function. It enables the stimulation. Abstract. AIMS To describe the topography of multifocal electroretinograms ( ERGs) and to explore its diagnostic value in patients with Stargardt’s macular.
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The electroretinogram ERG is a recording of the bioelectric potential, the summed activity of the retinal cells located at the elecctrorretinograma of the eye, when stimulated by light.
When bioelectrical changes occur within the retina, the change is propagated to the surface of the cornea. These small and often very fast signals can be captured by an electrkrretinograma placed on the surface of the cornea. In our lab, we record the ERG with an electrode embedded within a contact lens.
The signals are amplified and stored on a computer for further analysis. The first human ERG recordings were obtained in by James Dewar, but recordings were not stable enough for quantitative measurements until the introduction of the contact lens electrode in by Lorrin Riggs.
The electroretinogram can be elicited by different kinds of stimulation: In Erich Sutter developed a new method, combining the advantages of the focal and pattern stimulation into one procedure called multifocal ERG.
The subject fixates on the center of a display containing an array of hexagons that increase electrorretinorgama size from the center outward.
Multifocal Electroretinograms | Protocol
In our lab, we usually use hexagons that are displayed on a computer screen. Because the number of cone photoreceptors per area varies for different parts of the retina, the size of the hexagons is adjusted, so about the same number of cones will be stimulated by each hexagon.
Electrorretinogama the subject views the display, a single continuous electroretinogram recording is obtained. This recording takes less than 4 minutes. To make it easier for the person being tested, the recording is divided into short segments of 15 to 30 seconds. During the stimulation, the display appears to flicker because each hexagon goes through a pseudo-random sequence of black and white presentations.
The computer cross-correlates the fluctuations in voltage with each change in the m-sequence.
The produces multiple ERG recordings reflecting the retinal response of each of the corresponding stimulated area. The responses can be demonstrated by the multifocal ERG traces or in a 3-dimentional plot, reflecting the response density distribution across the stimulated area.
Multifocal ERG in Practice
The peak in the 3-D plot reflects the highest response density. In healthy eyes, this peak is generated by the cells in the fovea. This lowest response corresponds to the area of the optic nerve blue in the example. In this area there are no cones to generate a response i.
In people with macular degeneration the multifocal ERG technique is a useful tool to detect and quantify central cone function, especially in disease stages with no or subtle visible retinal changes.
The clinical example year-old patient with soft drusen, visual acuity: Our main focus is to investigate the normal age-related changes in multifocal ERG responses and to find out and quantify the underlying optical and neural factors contributing to those age-related changes see recent publications.
The multifocal electroretinogram.
Additionally, this research will provide a firm foundation for comparison with pathologic changes that occur in the retina. What is the Electroretinogram ERG? The multifocal Electroretinogram The subject fixates on the center of a display containing an array of hexagons that increase in size from the center outward.
Clinical Application In people with macular degeneration the multifocal ERG technique is a useful tool to detect and quantify central cone function, especially in disease stages with no or subtle visible retinal changes. Research Our main focus is to investigate the normal age-related changes in multifocal ERG responses and to electrorrdtinograma out and quantify the underlying optical and neural factors contributing to those age-related changes see recent publications.