Robert Noecker, MD, MBA, focuses his blog on the positive impact diagnostics and imaging have on various disease states and conditions. 

BLOG: Value of office-based ERG and VEP

Visual electrophysiology testing has become more accessible in recent years due to office-based equipment such as the Diopsys Nova ERG and VEP vision testing system.

Electroretinography (ERG) and visual evoked potentials (VEPs) specifically are of significant benefit as they objectively evaluate the function of the retina and visual system. Abnormalities can be detected much earlier than with traditional testing, and treatment can commence early enough to prevent permanent damage. While incorporating these systems into a practice represents an investment, it is well worth it in terms of convenience and better outcomes due to earlier diagnoses.

Practices with large populations of diabetic, cataract and glaucoma patients will find ERG tests particularly beneficial. Pattern ERGs (PERGs) can help detect early or changing diabetic retinopathy as well as track the efficacy of treatment. For cataract patients, flash ERGs (ffERGs) performed prior to surgery can detect any macular disease. This allows us to prepare the patient if their outcome may be affected by the pre-existing conditions in the retina or macula. If abnormalities are detected, we continue with the surgery and can address the outlying issues afterward.

PERGs are particularly valuable with glaucoma patients and suspects. Subjective diagnostic tools such as visual fields are not always reliable. With PERG, the greatest value comes in the ability to objectively detect dysfunction, in some cases several years earlier than with other diagnostics. If disease is detected, we can begin immediate treatment in order to reverse and improve cell function.

VEPs are also valuable for a variety of conditions. These include the early detection of amblyopia, the diagnosis and treatment of traumatic brain injuries, and unusual cases such as traumatic optic neuropathy or angiomas that may affect the optic nerve. Additionally, some conditions may masquerade as glaucoma, and VEP can differentiate between actual glaucoma or other issues such as an optic nerve glioma or anterior ischemic optic neuropathy. It is critical to determine the true problem, as the traditional glaucoma treatment of lowering pressure may not be the best treatment for these patients.

While there is always an art to diagnosis, ERGs and VEPs can bring confidence and peace of mind that nothing is being missed, especially for patients with family histories. They are an integral part of being a state-of-the-art facility and key for physicians who want to provide true value to their patients.


Banitt MR, et al. Invest Ophthalmol Vis Sci. 2013;doi:10.1167/iovs.12-11026.

Robert J. Noecker, MD, is a leading ophthalmologist with more than 15 years developing innovations in glaucoma surgery. He currently practices with Ophthalmic Consultants of Connecticut and is on the clinical faculty at Yale University. Noecker can be reached at

Disclosure: Noecker reports he is a consultant to Diopsys.