When viewing an image, the object is projected onto the retina at the back of the eye. The retina converts this optical image into very small electrical signals, which pass along the optic nerve to the brain, where the sensation of 'seeing' occurs.

Visual electrodiagnostics, also known as visual electrophysiology, measures these very small signals both in the eye and in the brain. These tests measure how well the retina and optic nerve work, and allow diagnosis of some disorders of the retina and brain.

The most common visual electrodiagnostic test is the electroretinogram (ERG). The ERG test of the retina is similar to the electrocardiogram (ECG) test of the heart.

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When the patient attends, a selection of tests will be performed depending on the reason for the referral.

  • Electro-Retinogram (ERG)
  • Multifocal Electro-Retinogram (mfERG)
  • Electro-Oculogram (EOG)
  • Visual-Evoked Responses (VER)


A/Prof Heather Mack