Electroretinogram, often referred to as an ERG, is a diagnostic test used to measure the electrical activity of the retina in response to light. Synonyms for the word ERG include electrodiagnostic testing, electroretinography, retinal function testing, and retinal potential testing. These terms may be used interchangeably in medical literature and discussions among healthcare professionals. Regardless of the specific terminology used, ERGs are an important tool in the diagnosis of a wide range of vision-related disorders, including retinal degeneration, diabetic retinopathy, and macular degeneration. Early detection and treatment of these conditions can significantly improve the patient's prognosis and quality of life.