Diagnostic Visual Electrophysiology Service

The Kellogg Eye Center provides electrophysiological and psychophysical tests for visual function assessment in the diagnosis, prognosis, and treatment of eye diseases.  The diagnostic tests reflect retinal, optic nerve, and visual pathway function.

Tests offered

  • Kinetic Visual Field Test with Goldmann perimeter (GVF)
  • Static Perimetry with Humphrey perimeter (HVF)
  • Color Vision - Ishihara, HRR, Farnsworth D-15, Farnsworth 100-Hue, Nagel Anamoloscope
  • Dark-adaptation (DA)
  • Electroretinogram (ERG)
    The electroretinogram (ERG) measures the mass electrical activity of the cells within the retina in response to light stimulation. It provides objective information about widespread retinal function of rods and cones, and of the inner retina. It is recorded using a contact lens electrode placed on the cornea after the patient is given topical anesthesia. The patient is presented with a flash of light, and the electrodes record the retinal potentials. The ERG is considered the primary diagnostic test for a variety of retinal dystrophies and degenerations (including retinitis pigmentosa and cone dystrophies), as well as inflammatory, vascular and toxic disorders.
  • Electro-oculogram (EOG)
  • Visual Evoked Potentials (VEP)
  • Multifocal ERG (MFERG)


Recommended Tests

Tentative  diagnosis Recommended Tests
Achromatopsia ERG, GVF, DA, Color
Age-Related Macular Degeneration
with light sensitivity
(Senile cone degeneration)
Albinism ERG, GVF
Best’s Disease ERG, GVF, EOG
Cone Dystrophy ERG, GVF, DA, Color
Inflammatory conditions ERG, GVF
Intraocular foreign bodies ERG, EOG
Night Blindness ERG, GVF, DA
Nystagmus ERG, Color
Optic Neuropathy VEP, Color, ERG
Opaque media or trauma ERG, GVF
Photophobia, decreased vision ERG, GVF, DA
Retinal Dystrophy ERG, GVF, DA, Color
Retinitis Pigmentosa ERG, GVF, DA
Retinoschisis ERG, GVF, DA, Color
Stargardt’s Macular Degeneration ERG, GVF, DA, EOG, Color
Toxic conditions ERG
Unexplained visual loss VEP, ERG, GVF


Diagnostic Visual Service Group

  • Naheed W. Khan, PhD, Co-Director    
  • Kari E. Branham, MS, CGC, Genetic Counselor
  • Ashley Moncrief Thompson, BS, Electrophysiology Technician



If you have questions or wish to refer a patient for diagnostic visual electrophysiology testing,  please call 734-764-4190.