What is a VEP?
The visual evoked potential (VEP) is a specialized objective measure of the visual pathway. The VEP has been used for many visual and neurological diagnoses, but our clinic focuses on the measurements for patients who have suffered traumatic brain injury (TBI).
Dr. Bill Padula began research in the 1990’s and investigating how the visual system was changed after suffering from an acquired brain injury or TBI or neuro-degenerative disorders. His early worked helped identify patients who may experience post-trauma vision syndrome. This measure is unique and powerful, because the data is purely objective. Dr. Padula found a specific protocol that is similar to the protocol utilized by Excel Neuro-Optometric Clinic to help identify disruptions in the visual system.
In his protocol he specifically uses prisms and occlusions to assess changes to the visual system to either confirm post-trauma vision syndrome or help with final prescription of prisms and/or occlusions. This has been an integral component to our clinic to gather a better understanding of the visual system. More recently, Dr. Ken Ciuffreda3,4 added more investigation to some of the work originally performed by Dr. Padula. His data and research that was complimentary of the work originally published by Dr. Padula, and represents the research, even in modern times, for vision and brain injury.
Our VEP protocol is traditionally used in those who have suffered TBI, however, VEP can be used in many other diagnoses. Research has also proven the visual system’s potential deficits associated with amblyopia and strabismus.5 This is crucial to understand that strabismus and amblyopia are not simply diagnosis of the eye, but transverse the visual pathway to the cortical level. In the research by Furtado de Mendonca, it was shown that there may actually be negative results with patching and the visual system to the BETTER SEEING EYE!5 Also, although patching or occlusion may yield visual acuity improvements, the area of improvement is limited to central visual processing (and more specifically one quadrant of central processing). In addition, patching may not be as effective in milder forms of amblyopia (i.e., 20/100 or better visual acuity) versus dense amblyopia. Improvements in central processing on the VEP do not always correlate with improved measurable visual acuity (e.g., Snellen acuity).6 Patching may be a tool to use in rehabilitation, but there is more to vision than visual acuity!
4. Ciuffreda KJ, Yadav NK, Ludlam DP. Binasal Occlusion (BNO), Visual Motion Sensitivity (VMS), and the Visually-Evoked Potential (VEP) in mild Traumatic Brain Injury and Traumatic Brain Injury (mTBI/TBI). Brain Sci. 2017;7(8):98.
6. Jang J, Kyung SE. Assessing amblyopia treatment using multifocal visual evoked potentials. BMC Ophthalmology. 2018;18:196.