Electroretinography (A Review)

Electroretinography (ERG) is a functional test of the outer retina. During an examination, the retina is selectively stimulated. The stimulation of the retina produces a response of the individual retinal cells and reveals information about its function. The ERG examination requires very specific conditions in order to avoid undesirable factors which may adversely affect the recordings. The electroretinography examination may be performed for a short period (“rapid protocol”), commonly used to access retinal activity. The “long protocol” is used for the differential diagnosis of retinal disorders. It is mainly used in diagnosing and evaluating retinal dysfunction when there are no ophthalmic lesions present. The main indications for electroretinography are the pre-operative examination of cataract patient and the early diagnosis of inherited retinal diseases. In veterinary ophthalmology, ERG is performed under general anesthesia. The ERG results have wave forms with characteristic components depending upon several factors. Its interpretation requires knowledge of retinal pathology and electrophysiology