ffERG

ffERG, or full-field electroretinography, is a diagnostic test that records the summed electrical responses of the retina to standardized light stimuli delivered to the entire retina using a Ganzfeld stimulus. It provides information about overall retinal function, particularly the photoreceptors and inner retinal cells, and is used to assess both rod and cone systems.

During ffERG testing, patients are typically prepared with appropriate pupil dilation and, depending on the protocol, dark- or light-adaptation. Corneal or conjunctival electrodes record the retinal signal while flashes of light of varying intensities are presented. The main components observed are the a-wave, reflecting photoreceptor activity, and the b-wave, arising from bipolar and Müller cells. In addition, flicker responses at higher frequencies are used to evaluate cone function. The responses are interpreted within standardized protocols set by professional bodies.

ffERG is employed in the evaluation of a wide range of retinal conditions, including hereditary rod- and cone-dystrophies, retinitis pigmentosa, cone-rod dystrophy, and other degenerative or toxic retinopathies. It is also used to monitor disease progression or response to treatment and to assess retinal function prior to certain ocular interventions. ISCEV standards provide the recommended testing procedures and normative criteria to enable consistent interpretation across clinics and research settings.

Limitations of ffERG include dependence on adequate media clarity, proper electrode placement, and patient cooperation. Because it measures global retinal function, it may not detect small, localized abnormalities; for regional testing, multifocal ERG is used as a complementary modality.