Electroretinography 3 JAXLA_ERG_003

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Purpose

Full-field electroretinogram (ERG) is a mass electrical response of the retina to a light stimulus. The ERG contains four components: a-wave, b-wave, c-wave and FO-wave. These four components reflect the responsiveness of retinal photoreceptor cells and other neurons as a measure of visual function.

Experimental Design

 

Equipment

Celeris - Diagnosys LLC

Procedure

Procedure

  1. Transfer mice from the animal room to the testing room.
  2. Mice are dark adapted overnight (alternatively: minimum of 2 hours) for testing procedures.
    1. All rod testing procedures are done under dim red light after a minimum 2-hour dark adaptation period
  3. Following dark adaptation one drop of Cyclomydril Ophthalmic Drops 0.2% (alternatively: Cyclopentolate Hydrochloride ophthalmic Sol 1%) is applied to each eye to induce mydriasis.
  4. Once the pupils have dilated mice are anesthetized with the inhalation of 2% Isoflurane.
  5. When the mouse has reached the proper plane of anesthesia, the mouse is placed on a heated platform and the nose is placed in the nose cone for continuous anesthetic inhalation.
  6. Goniovisc Ophthalmic Drops 2.5% (alternatively: Refresh Celluvisc) is applied to the electrodes before placing on each cornea.
  7. The scotopic test is performed with pulsing white light.
  8. A 3-minute light-adaptation follows before the photopic test is run. At this time an additional drop of oopthalmic lubricant should be added to each eye without adjusting the electrodes.
  9. After 3 minutes of light adaptation, photopic ERGs are obtained with brighter white flashes at varying stimulation intensities.
  10. Once the photopic test is complete, carefully remove the recording electrodes and apply a generous amount of Puralube/Systane ophthalmic gel to both eyes and allow the mouse to recover in a clean heated pen until fully conscious.
  11. Return the mouse to its home pen.
  12. Clean the electrodes with sterile water followed by 70% ethanol.
  13. Save the test results and export to the server.

Notes

Amplitude and timing measures of the ERG waveform are taken:

  1. The a-wave amplitude is measured from the pre-stimulus baseline to the lowest negative trough; the b-wave amplitude is measured from the trough of the a-wave to the following highest peak; the c-wave amplitude is measured from the pre-stimulus baseline to the following highest peak; the FO- wave amplitude is measured from the peak of the c-wave to the subsequent lowest trough.
  2. Implicit time (t) is measured from stimulus onset to the trough or peak of each wave.

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