J Korean Ophthalmol Soc.  2003 Mar;44(3):732-737.

Cortical Responses Evoked by the Light and Electricity in the Rabbit Retina

• Kim SJ
• Yu HG
• Yu YS
• Chung H
• Chang BL

Abstract

PURPOSE
By recording the electrically evoked potential (EEP) we tried to verify that focal electrical stimulation of retina sends a signal to the cortex that is similar to that elicited by light and also to investigate optimal stimulus parameters. METHODS: Five New Zealand white rabbits were placed under anesthesia. A tungsten bipolar stimulating electrode (diameter: 250 um) was placed on the vitreal surface of the retina. Cutaneous Ag/AgCl patch electrodes of VEP were used to record EEP. EEP was recorded at each stimulation. Focal visual evoked potentials (VEPs) were also recorded and compared to the focal EEP to ascertain cortical origin of the EEP, and similarities of the EEP to the VEP were determined. RESULTS: EEP recordings were elicited in 8 eyes. Current amplitudes which produced detectable responses ranged from 100 to 5000 micro A. In our best series, EEP amplitudes increased by 8 to 119 micro V in response to the current increasing from 100 to 1000 micro A. In comparing latencies of the EEP and focal VEP, the EEP latencies were 12~16 ms faster, which supports our EEP recording was done properly. CONCLUSIONS: EEPs obtained using VEP setting with adequate parameters of current duration and threshold level for the retinal implant showed that use of the EEP response is a good way to monitor the proper functioning of the retinal implant.

Keyword

Electrically evoked potential; Electrophysiology; Retinal prosthesis; Visual evoked potential(VEP)

MeSH Terms

Anesthesia
Electric Stimulation
Electricity*
Electrodes
Electrophysiology
Evoked Potentials
Evoked Potentials, Visual
Rabbits
Retina*
Retinaldehyde
Tungsten
Visual Prosthesis
Retinaldehyde
Tungsten