Effect of Axial Length on Full-Field and Multifocal Electroretinogram

Abstract

he Electroretinogram is a mass potential, which reflects the summed electrical activity of the retina. Full-field ERG measures the electrical signals from the whole retina in response to a light stimulus. The weakness of the full-field ERG is that it cannot provide topographical information regarding the functional integrity of the retina and cannot detect subtle functional defects. The response is dominated by the peripheral retina due to its predominance of retinal cells. Multifocal ERG can examine the local response of a particular retinal locus by varying the size and location of the stimulating beam. It provides a retinal response from different locations but requires multiple measurements. It is less effective in terms of clinical use, if measurement of multiple retinal loci is needed. It is usually limited to measurement of the macular response. Axial length is the distance from the anterior corneal surface to the retinal pigment epithelium. It can be performed using optical or ultrasound methods, The axial length of the eye at birth is approximately 17 mm and reaches approximately 24 mm in adulthood.